Co-reporter:Wencheng Du;Mingmao Wu;Miao Zhang;Guochuang Xu;Tiantian Gao;Liu Qian;Xiaowen Yu;Fengyao Chi;Chun Li
Chemical Communications 2017 vol. 53(Issue 80) pp:11005-11007
Publication Date(Web):2017/10/05
DOI:10.1039/C7CC04584K
We report a simple method that can dissolve graphene oxide (GO) in pure organic solvents (e.g., propylene carbonate) as readily as in pure water to form stable dispersions of single layer GO sheets. The GO sheets dispersed in propylene carbonate exhibited much better structural stability than those in water.
Co-reporter:Yue Tong;Xiaowen Yu
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 6) pp:4821-4826
Publication Date(Web):2017/02/08
DOI:10.1039/C6CP08176B
The development of ecofriendly electrocatalysts with earth-abundant metal elements for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is important for overall water splitting to generate clean and sustainable chemical energy. Here, we report a self-standing cobalt disulfide/graphite foam (CoS2/GF) electrocatalytic electrode for this purpose. It showed high catalytic activities for both the HER and OER, requiring only a cell voltage of 1.74 V to achieve a current density of 20 mA cm−2 for overall water splitting in an alkaline electrolyte. This three-dimensional microporous electrocatalytic electrode is cheap and available in a large area; thus, it is attractive for practical applications.
Co-reporter:Bowen Yao;Haiyan Wang;Qinqin Zhou;Mingmao Wu;Miao Zhang;Chun Li
Advanced Materials 2017 Volume 29(Issue 28) pp:
Publication Date(Web):2017/07/01
DOI:10.1002/adma.201700974
A poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) hydrogel is prepared by thermal treatment of a commercial PEDOT:PSS (PH1000) suspension in 0.1 mol L−1 sulfuric acid followed by partially removing its PSS component with concentrated sulfuric acid. This hydrogel has a low solid content of 4% (by weight) and an extremely high conductivity of 880 S m−1. It can be fabricated into different shapes such as films, fibers, and columns with arbitrary sizes for practical applications. A highly conductive and mechanically strong porous fiber is prepared by drying PEDOT:PSS hydrogel fiber to fabricate a current-collector-free solid-state flexible supercapacitor. This fiber supercapacitor delivers a volumetric capacitance as high as 202 F cm−3 at 0.54 A cm−3 with an extraordinary high-rate performance. It also shows excellent electrochemical stability and high flexibility, promising for the application as wearable energy-storage devices.
Co-reporter:Liu Qian;Yilin Sun;Mingmao Wu;Dan Xie;Liming Ding
Advanced Materials 2017 Volume 29(Issue 22) pp:
Publication Date(Web):2017/06/01
DOI:10.1002/adma.201606175
Phototransistors with a structure of a nitrogen-doped graphene quantum dots (NGQDs)–perovskite composite layer and a mildly reduced graphene oxide (mrGO) layer are fabricated through a solution-processing method. This hybrid phototransistor exhibits broad detection range (from 365 to 940 nm), high photoresponsivity (1.92 × 104 A W−1), and rapid response to light on–off (≈10 ms). NGQDs offer an effective and fast path for electron transfer from the perovskite to the mrGO, resulting in the improvement of photocurrent and photoswitching characteristics. The high photoresponsivity can also be ascribed to a photogating effect in the device. In addition, the phototransistor shows good stability with poly(methyl methacrylate) encapsulation, and can maintain 85% of its initial performance for 20 d in ambient air.
Co-reporter:Guochuang Xu, Ji Chen, Miao Zhang, Gaoquan Shi
Sensors and Actuators B: Chemical 2017 Volume 242() pp:418-422
Publication Date(Web):April 2017
DOI:10.1016/j.snb.2016.11.068
•A moisture driven actuator was prepared by using small flakes of graphene oxide (SGO) as the actuation material.•The SGO film can adsorb about 22 wt% of water compared with its own weight by changing relative humidity (RH) from 20% to 50%.•An SGO/reduced conventional GO bilayer actuator showed superior actuation performance.•The actuator can move an object 30 times heavier than its own weight.Moisture driven actuators with sensitive and strong actuation performances have important applications in robots, artificial muscles and hygrometers, etc. Here, we report such an actuator constructed by one layer of small flakes of graphene oxide (SGO) with an average lateral dimension of 0.9 μm and another layer of reduced conventional graphene oxide sheets (rCGO). An SGO film can adsorb about 22% (by weight, wt%) of water compared with its own weight by changing relative humidity (RH) from 20% to 50%. This SGO film can generate a contractile stress up to 90 MPa as relative humidity (RH) changed from 100% to 23%. An SGO/rCGO bilayer actuator with a thickness of 2.3 μm displayed an extremely large curvature (about 19.1 cm−1) at an RH of 98%. This actuator also exhibited a high rate of bending (4.4 cm−1 s−1) in the first second as RH switched from 75% to 32%. It showed excellent stability (kept unchanged after actuating for 1000 cycles), and was capable of moving an object 30 times heavier than its own weight.
Co-reporter:Yeye Wen;Mingmao Wu;Miao Zhang;Chun Li
Advanced Materials 2017 Volume 29(Issue 41) pp:
Publication Date(Web):2017/11/01
DOI:10.1002/adma.201702831
AbstractNacre-like graphene films are prepared by evaporation-induced assembly of graphene oxide dispersions containing small amounts of cellulose nanocrystal (CNC), followed by chemical reduction with hydroiodic acid. CNC induces the formation of wrinkles on graphene sheets, greatly enhancing the mechanical properties of the resultant graphene films. The graphene films deliver an ultrahigh tensile strength of 765 ± 43 MPa (up to 800 MPa in some cases), a large failure strain of 6.22 ± 0.19%, and a superior toughness of 15.64 ± 2.20 MJ m−3, as well as a high electrical conductivity of 1105 ± 17 S cm−1. They have a great potential for applications in flexible electronics because of their combined excellent mechanical and electrical properties.
Co-reporter:Shan Chen
Advanced Materials 2017 Volume 29(Issue 24) pp:
Publication Date(Web):2017/06/01
DOI:10.1002/adma.201605448
Halide perovskites have high light absorption coefficients, long charge carrier diffusion lengths, intense photoluminescence, and slow rates of non-radiative charge recombination. Thus, they are attractive photoactive materials for developing high-performance optoelectronic devices. These devices are also cheap and easy to be fabricated. To realize the optimal performances of halide perovskite-based optoelectronic devices (HPODs), perovskite photoactive layers should work effectively with other functional materials such as electrodes, interfacial layers and encapsulating films. Conventional two-dimensional (2D) materials are promising candidates for this purpose because of their unique structures and/or interesting optoelectronic properties. Here, we comprehensively summarize the recent advancements in the applications of conventional 2D materials for halide perovskite-based photodetectors, solar cells and light-emitting diodes. The examples of these 2D materials are graphene and its derivatives, mono- and few-layer transition metal dichalcogenides (TMDs), graphdiyne and metal nanosheets, etc. The research related to 2D nanostructured perovskites and 2D Ruddlesden–Popper perovskites as efficient and stable photoactive layers is also outlined. The syntheses, functions and working mechanisms of relevant 2D materials are introduced, and the challenges to achieving practical applications of HPODs using 2D materials are also discussed.
Co-reporter:Qinqin Zhou, Mingmao Wu, Miao Zhang, Guochuang Xu, Bowen Yao, Chun Li, Gaoquan Shi
Materials Today Energy 2017 Volume 6(Volume 6) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.mtener.2017.09.015
•The electrochemical capacitors based on densified hydrogel films of highly defective graphene sheets show integrated high-performance.•Highly defective structures can partly prevent the restacking of graphene sheets.•The conductivity and ions diffusion channels of a graphene electrode depend on the lateral sizes of graphene sheets.The rapid development of portable electronics and hybrid vehicles requires electrochemical capacitors (ECs) with excellent integrated performances. Herein, we report such an EC based on the dense graphene hydrogel films (packing density = 1.18 ± 0.01 g cm−3) prepared by hydrothermal reduction of highly oxidized graphene oxide (HGO) sheets with lateral dimensions of 1–2 μm, followed by mechanical compression. This EC exhibited high areal (366 ± 6 mF cm−2), gravimetric (232 ± 3 F g−1) and volumetric (273 ± 1 F cm−3) specific capacitances at 1 A g−1, ultrahigh rate-capability (80% capacitance retention at 100 A g−1), and good electrochemical stability. The effects of the structural defects and lateral sizes of graphene sheets on their electrochemical performances are studied, offering a guidance of rational designing graphene materials for their applications in ECs.An electrochemical capacitor based on highly defective graphene sheets with optimized sizes of 1 to 2 micrometers exhibits high areal, gravimetric and volumetric capacitances, ultrahigh rate-capability, and excellent electrochemical stability.Download high-res image (166KB)Download full-size image
Co-reporter:Tiantian Gao, Liang Huang, Chun Li, Guochuang Xu, Gaoquan Shi
Carbon 2017 Volume 124(Volume 124) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.carbon.2017.08.042
Organic solvent nanofiltration (OSN) membranes with excellent and tuneable molecular separation performances are important in pharmaceutical industry. Here, we report reduced graphene oxide (rGO) membranes intercalated with self-assembled 5, 10, 15, 20-tetrakis (1-methyl-4-pyridinio) porphyrin (TMPyP) molecules for this purpose. These membranes showed strong tolerances to water and various organic solvents and their OSN performances can be easily tuned by controlling the amount of intercalated porphyrin molecules. The methanol permeance of an rGO membrane (mass loading = 44 mg m−2) was increased by 2 times upon intercalating 60% TMPyP relative to its own weight. This composite membrane also exhibited high rejection (>92%) for negatively charged organic dyes with molecular dimensions larger than 1.7 nm in methanol. As a demonstration, it was used to separate vitamin B12 from its aqueous or methanol solution, exhibiting a solvent permeance of 5.76 or 4.40 L m−2 h−1 bar−1 and a rejection of 98.4% or 91.0%.Download high-res image (254KB)Download full-size image
Co-reporter:Yue Zhuang;Wenjing Yuan;Liu Qian;Shan Chen
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 20) pp:12876-12881
Publication Date(Web):2017/05/24
DOI:10.1039/C7CP01646H
Thin films of a thiocyanate ion (SCN−)-doped organometal halide perovskite, CH3NH3PbI3−x(SCN)x, were used as a sensing material for developing high-performance gas sensors. The CH3NH3PbI3−x(SCN)x-based chemiresistor-type sensor can sensitively and selectively detect acetone and nitrogen dioxide (NO2) at room temperature with high sensitivities of 5.6 × 10−3 and 5.3 × 10−1 ppm−1. The limits of detection for acetone and NO2 were measured to be 20 ppm and 200 ppb. This sensor also exhibited excellent repeatability, and its environmental stability was greatly improved by doping the perovskite with SCN− ions.
Co-reporter:Guochuang Xu;Miao Zhang;Qinqin Zhou;Hongwu Chen;Tiantian Gao;Chun Li
Nanoscale (2009-Present) 2017 vol. 9(Issue 44) pp:17465-17470
Publication Date(Web):2017/11/16
DOI:10.1039/C7NR07116G
A high-performance actuator should be able to deliver large-shape deformations, fast actuations and sensitive responses to multiple stimuli. Here, we report such an actuator constructed from one layer of polyvinylidene fluoride (PVDF) with a high coefficient of thermal expansion (CTE), and another layer of small sheets of graphene oxide (SGO) with a negative CTE. The opposite deformations of both actuation layers make the SGO/PVDF bilayer actuator highly sensitive to the temperature stimulus with a large bending sensitivity of 1.5 cm−1 °C−1. Upon irradiation with 60 mW cm−2 infrared light, this SGO/PVDF bilayer actuator displayed an extremely rapid tip displacement rate of 140 mm s−1. Furthermore, this actuator can also sensitively respond to moisture because of its SGO layer, showing a curvature change from −22 to 13 cm−1 upon changing the relative humidity (RH) from 11% to 86%. This actuator can generate a contractile or relaxed stress 18 times that of mammalian skeletal muscle, under light irradiation or moisture with a response time as short as 1 s, being capable of lifting an object with a weight 80 times that of itself. Furthermore, it also showed excellent stability and repeatability.
Co-reporter:Zhengran Yi;Zheye Zhang;Shuai Wang
Journal of Materials Chemistry A 2017 vol. 5(Issue 2) pp:519-523
Publication Date(Web):2017/01/03
DOI:10.1039/C6TA09315A
A bioinspired polydopamine derivative was prepared by self-polymerization of 6-(2-aminoethyl)-3-hydroxypyridin-2(1H)-one (AHPO) in an alkaline aqueous medium. It was used as a precursor to produce nanocapsules of pyridinic N-rich carbon with a desired N doping content by using silica nanoparticles as the template. These N-doped nanocapsules exhibited superior electrocatalytic activity and stability towards the oxygen reduction reaction (ORR), lending an attractive alternative to the Pt catalyst. This work provides an important insight into the rational designing of bioinspired polymers for the development of functional carbon materials with excellent properties.
Co-reporter:Hongyun Ma;Chun Li;Miao Zhang;Jong-Dal Hong
Journal of Materials Chemistry A 2017 vol. 5(Issue 32) pp:17040-17047
Publication Date(Web):2017/08/15
DOI:10.1039/C7TA04771A
Hydrothermal carbonization (HTC) is a conventional method to synthesise biomass-derived carbon materials. However, hydrothermal treatment of proteins usually induces the decomposition of these biopolymers without forming carbonaceous materials. Here, we report the use of graphene oxide sheets as a template and catalyst to carbonize egg proteins via HTC. The resulting egg protein derived carbon/reduced graphene oxide (EDC/rGO) composite was further activated using KOH to produce a highly porous heteroatom-doped carbon material and used as an electrode material for a supercapacitor. The typical supercapacitor exhibited a high specific capacitance (482 F g−1 at a current density of 0.1 A g−1), good rate capability and excellent cycling stability (∼100% capacitance retention after 10 000 cycles of charging and discharging at 5 A g−1). Considering the high efficiency of the HTC process and the low cost of eggs, this work demonstrates a facile approach to produce high-performance carbon-based electrode materials for supercapacitors.
Co-reporter:Miao Zhang, Qinqin Zhou, Ji Chen, Xiaowen Yu, Liang Huang, Yingru Li, Chun Li and Gaoquan Shi
Energy & Environmental Science 2016 vol. 9(Issue 6) pp:2005-2010
Publication Date(Web):20 Apr 2016
DOI:10.1039/C6EE00615A
Alternating current (AC) line-filters are widely used to attenuate the leftover AC ripples in line-powered devices. However, the commercialized aluminum electrolytic capacitors (AECs) have low specific capacitances, making them usually the largest components in the electronic circuits of miniaturized, portable and/or flexible electronics. Herein, we report a scalable wet-process to fabricate an electrochemical capacitor (EC) using sulfuric acid treated commercially available poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (AT-PEDOT:PSS) as an electrode material and graphite foil as the current collector. It exhibited high areal (994 μF cm−2) and volumetric (16.6 F cm−3) specific capacitances at 120 Hz, ultrahigh-rate frequency response (phase angle = −83.6° at 120 Hz) with a short resistor–capacitor time constant of 0.15 ms, and an excellent electrochemical stability. Therefore, it is promising to replace AECs for AC line-filtering, and their performance is superior to those of the state-of-the-art ECs for this purpose.
Co-reporter:Bowen Yao;Ji Chen;Liang Huang;Qinqin Zhou
Advanced Materials 2016 Volume 28( Issue 8) pp:1623-1629
Publication Date(Web):
DOI:10.1002/adma.201504594
Co-reporter:Shan Chen;Changjiu Teng;Miao Zhang;Yingru Li;Dan Xie
Advanced Materials 2016 Volume 28( Issue 28) pp:5969-5974
Publication Date(Web):
DOI:10.1002/adma.201600468
Co-reporter:Xiaowen Yu;Miao Zhang;Ji Chen;Yingru Li
Advanced Energy Materials 2016 Volume 6( Issue 2) pp:
Publication Date(Web):
DOI:10.1002/aenm.201501492
The oxidation of water to produce oxygen gas is related to a variety of energy storage systems. Thus, the development of efficient, cheap, durable, and scalable electrocatalysts for oxygen evolution reaction (OER) is of great importance. Here, a high-performance OER catalyst, nitrogen and sulfur codoped graphite foam (NSGF) is reported. This NSGF is prepared from commercial graphite foil and directly applied as an electrocatalytic electrode without using a current collector and a polymeric binder. It exhibits an extremely low overpotential of 0.380 V to reach a current density of 10 mA cm−2 and shows fast kinetics with a small Tafel slope of 96 mV dec−1 in 0.1 m KOH. This electrocatalytic performance is superior or comparable to those of previously reported metal-free OER catalysts.
Co-reporter:Ji Chen, Yao Zhang, Miao Zhang, Bowen Yao, Yingru Li, Liang Huang, Chun Li and Gaoquan Shi
Chemical Science 2016 vol. 7(Issue 3) pp:1874-1881
Publication Date(Web):26 Nov 2015
DOI:10.1039/C5SC03828F
Graphene oxide (GO) sheets with controlled species of oxygen-containing groups are important for fabricating graphene materials with desired structures and properties. Here we report a water-addition modified Hummers method to prepare GO sheets with tunable amounts of hydroxyl and epoxide groups without destroying their structural integrity. This method is simple, effective, and efficient. It can be applied to the mass-production of GO with controlled amounts and species of oxygenated groups, and improve the yields of synthesizing high-quality GO at low temperatures.
Co-reporter:Qinqin Zhou, Miao Zhang, Ji Chen, Jong-Dal Hong, and Gaoquan Shi
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 32) pp:20741
Publication Date(Web):July 25, 2016
DOI:10.1021/acsami.6b05601
The commercialized aluminum electrolytic capacitors (AECs) currently used for alternating current (AC) line-filtering are usually the largest components in the electronic circuits because of their low specific capacitances and bulky sizes. Herein, nitrogen-doped holey graphene (NHG) films were prepared by thermal annealing the composite films of polyvinylpyrrolidone (PVP), graphene oxide (GO), and ferric oxide (Fe2O3) nanorods followed by chemical etching with hydrochloride acid. The typical electrochemical capacitor with NHG electrodes exhibited high areal and volumetric specific capacitances of 478 μF cm–2 and 1.2 F cm–3 at 120 Hz, ultrafast frequency response with a phase angle of −81.2° and a resistor–capacitor time constant of 203 μs at 120 Hz, as well as excellent cycling stability. Thus, it is promising to replace conventional AEC for AC line-filtering in miniaturized electronics.Keywords: AC line-filtering; holey graphene; meso-/macropores; nitrogen doping; ultrafast electrochemical capacitors
Co-reporter:Rui Li, Miao Zhang, Yingru Li, Ji Chen, Bowen Yao, Mingpeng Yu and Gaoquan Shi
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 16) pp:11104-11110
Publication Date(Web):18 Mar 2016
DOI:10.1039/C6CP00512H
The microstructures and properties of the carbonaceous matrices in the cathodes of lithium–sulfur (Li–S) batteries have strong effects on their performances. We prepared a ternary composite cathode of mildly reduced less defective graphene oxide (mrLGO), sulfur, and carbon nanotubes (CNTs) by filtration for Li–S batteries. This battery showed a high initial specific capacity of 1219 mA h g−1 at 0.2 C and a stable specific capacity of around 1000 mA h g−1 after 200 cycles with a coulombic efficiency of 99%. Its excellent performance is mainly attributed to the good conductivity and residual oxygen containing groups of mrLGO, and the three-dimensional (3D) framework constructed using mrLGO sheets and CNTs.
Co-reporter:Qinqin Zhou;Shan Chen;Miao Zhang;Liduo Wang;Yingru Li
Chinese Journal of Chemistry 2016 Volume 34( Issue 1) pp:59-66
Publication Date(Web):
DOI:10.1002/cjoc.201500609
Abstract
Sulfuric acid-treated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/less-defective reduced graphene oxide (ST-PEDOT:PSS/L-rGO) composite films were prepared via a solution-processing route and used as the counter electrodes of dye sensitized solar cells (DSSCs). These platinum (Pt)- and transparent conductive oxide (TCO)-free counter electrodes exhibited strong catalytic activity and excellent flexibility, showing no obvious change in their sheet resistances after 10000 cycles of bending. The integrated quasi-solid-state DSSC device with a TiO2 nanotube/Ti mesh photoanode and a ST-PEDOT:PSS/L-rGO counter electrode exhibited an energy conversion efficiency (η) of about 1.8%. It also displayed an excellent mechanical stability and durability after bending for 1000 cycles at a small curvature radius of 10 mm. The high flexibility, low cost and efficient catalytic activity make ST-PEDOT:PSS/L-rGO composite films promising counter electrodes for flexible DSSCs.
Co-reporter:Gaoquan Shi
Chinese Journal of Chemistry 2016 Volume 34( Issue 1) pp:
Publication Date(Web):
DOI:10.1002/cjoc.201690002
No abstract is available for this article.
Co-reporter:Qiang Liu, Ji Chen, Yingru Li, and Gaoquan Shi
ACS Nano 2016 Volume 10(Issue 8) pp:7901
Publication Date(Web):July 27, 2016
DOI:10.1021/acsnano.6b03813
Strain sensors with large stretchability, broad sensing range, and high sensitivity are highly desirable because of their potential applications in electronic skins and health monitoring systems. In this paper, we report a high-performance strain sensor with a fish-scale-like graphene-sensing layer. This strain sensor can be fabricated via stretching/releasing the composite films of reduced graphene oxide and elastic tape, making the process simple, cheap, energy-saving, and scalable. It can be used to detect both stretching and bending deformations with a wide sensing range (up to 82% strain), high sensitivity (a gauge factor of 16.2 to 150), ultralow limit of detection (<0.1% strain), and excellent reliability and stability (>5000 cycles). Therefore, it is attractive and promising for practical applications, such as for the full-range detection of human motions.Keywords: fish scale; graphene; human motion; strain sensor
Co-reporter:Jingsong Xu;Ji Chen;Miao Zhang;Jong-Dal Hong
Advanced Electronic Materials 2016 Volume 2( Issue 6) pp:
Publication Date(Web):
DOI:10.1002/aelm.201600022
A facile method is reported to prepare highly conductive stretchable wavy reduced graphene oxide (rGO) films by in situ reducing blade-coated graphene oxide films on elastic tapes. The sheet resistance of a 1.20 μm thick rGO film coated elastic tape is measured to be as low as 21 Ω sq−1 and it does not change during 1000 cycles of stretching/releasing with a maximum strain of 100%. The wavy rGO film can also be detached from its elastic substrate into a freestanding state, keeping its excellent elasticity. This in situ reduction method does not involve film transfer and high-temperature annealing; thus it is convenient and scalable. A solid-state electrochemical capacitor with these rGO electrodes shows large areal specific capacitance, and excellent electrochemical stability and flexibility.
Co-reporter:Xiluan Wang and Gaoquan Shi
Energy & Environmental Science 2015 vol. 8(Issue 3) pp:790-823
Publication Date(Web):07 Jan 2015
DOI:10.1039/C4EE03685A
Graphene is a unique and attractive energy material because of its atom-thick two-dimensional structure and excellent properties. Graphene sheets are also mechanically strong and flexible. Thus, graphene materials are expected to have wide and practical applications in bendable, foldable and/or stretchable devices related to energy conversion and storage. We present a review on the recent advancements in flexible graphene energy devices including photovoltaic devices, fuel cells, nanogenerators (NGs), supercapacitors (SCs) and batteries, and the devices related to energy conversion such as organic light-emitting diodes (OLEDs), photodetectors and actuators. The strategies for synthesizing flexible graphene materials will be summarized and the challenges facing the design and construction of the devices will be discussed.
Co-reporter:Yuxi Xu, Gaoquan Shi, and Xiangfeng Duan
Accounts of Chemical Research 2015 Volume 48(Issue 6) pp:1666
Publication Date(Web):June 4, 2015
DOI:10.1021/acs.accounts.5b00117
Graphene and its derivatives are versatile building blocks for bottom-up assembly of advanced functional materials. In particular, with exceptionally large specific surface area, excellent electrical conductivity, and superior chemical/electrochemical stability, graphene represents the ideal material for various electrochemical energy storage devices including supercapacitors. However, due to the strong π–π interaction between graphene sheets, the graphene flakes tend to restack to form graphite-like powders when they are processed into practical electrode materials, which can greatly reduce the specific surface area and lead to inefficient utilization of the graphene layers for electrochemical energy storage. The self-assembly of two-dimensional graphene sheets into three-dimensional (3D) framework structures can largely retain the unique properties of individual graphene sheets and has recently garnered intense interest for fundamental investigations and potential applications in diverse technologies.In this Account, we review the recent advances in preparing 3D graphene macrostructures and exploring them as a unique platform for supercapacitor applications. We first describe the synthetic strategies, in which reduction of a graphene oxide dispersion above a certain critical concentration can induce the reduced graphene oxide sheets to cross-link with each other via partial π–π stacking interactions to form a 3D interconnected porous macrostructure. Multiple reduction strategies, including hydrothermal/solvothermal reduction, chemical reduction, and electrochemical reduction, have been developed for the preparation of 3D graphene macrostructures. The versatile synthetic strategies allow for easy incorporation of heteroatoms, carbon nanomaterials, functional polymers, and inorganic nanostructures into the macrostructures to yield diverse composites with tailored structures and properties. We then summarize the applications of the 3D graphene macrostructures for high-performance supercapacitors. With a unique framework structure in which the graphene sheets are interlocked in 3D space to prevent their restacking, the graphene macrostructures feature very high specific surface areas, rapid electron and ion transport, and superior mechanical strength. They can thus be directly used as supercapacitor electrodes with excellent specific capacitances, rate capabilities, and cycling stabilities. We finally discuss the current challenges and future opportunities in this research field.By regarding the graphene as both a single-atom-thick carbon sheet and a conjugated macromolecule, our work opens a new avenue to bottom-up self-assembly of graphene macromolecule sheets into functional 3D graphene macrostructures with remarkable electrochemical performances. We hope that this Account will promote further efforts toward fundamental investigation of graphene self-assembly and the development of advanced 3D graphene materials for their real-world applications in electrochemical energy storage devices and beyond.
Co-reporter:Ji Chen;Yingru Li;Liang Huang;Naer Jia;Chun Li
Advanced Materials 2015 Volume 27( Issue 24) pp:3654-3660
Publication Date(Web):
DOI:10.1002/adma.201501271
Co-reporter:Liang Huang;Yingru Li;Qinqin Zhou;Wenjing Yuan
Advanced Materials 2015 Volume 27( Issue 25) pp:3797-3802
Publication Date(Web):
DOI:10.1002/adma.201500975
Co-reporter:Miao Zhang;Yanlei Wang;Liang Huang;Zhiping Xu;Chun Li
Advanced Materials 2015 Volume 27( Issue 42) pp:6708-6713
Publication Date(Web):
DOI:10.1002/adma.201503045
Co-reporter:Wenjing Yuan, Qinqin Zhou, Yingru Li and Gaoquan Shi
Nanoscale 2015 vol. 7(Issue 39) pp:16361-16365
Publication Date(Web):02 Sep 2015
DOI:10.1039/C5NR04312C
We report an efficient and cheap strategy to construct strain sensors by assembling reduced graphene oxide (rGO) sheets onto human hairs. These sensors are small, light and robust, and can be shaped into different structures such as fibre, spring and network. They can be used to detect various deformations including stretching, bending and compression with excellent repeatability and durability.
Co-reporter:Mingpeng Yu, Aiji Wang, Fuyang Tian, Hongquan Song, Yinshu Wang, Chun Li, Jong-Dal Hong and Gaoquan Shi
Nanoscale 2015 vol. 7(Issue 12) pp:5292-5298
Publication Date(Web):06 Feb 2015
DOI:10.1039/C5NR00166H
A reduced graphene oxide (rGO)-sulfur composite aerogel with a compact self-assembled rGO skin was further modified by an atomic layer deposition (ALD) of ZnO or MgO layer, and used as a free-standing electrode material of a lithium-sulfur (Li-S) battery. The rGO skin and ALD-oxide coating worked as natural and artificial barriers to constrain the polysulfides within the cathode region. As a result, the Li-S battery based on this electrode material exhibited superior cycling stability, good rate capability and high coulombic efficiency. Furthermore, ALD-ZnO coating was tested for performance improvement and found to be more effective than ALD-MgO coating. The ZnO modified G-S electrode with 55 wt% sulfur loading delivered a maximum discharge capacity of 998 mA h g−1 at a current density of 0.2 C. A high capacity of 846 mA h g−1 was achieved after charging/discharging for 100 cycles with a coulombic efficiency of over 92%. In the case of using LiNO3 as a shuttle inhibitor, this electrode showed an initial discharge capacity of 796 mA h g−1 and a capacity retention of 81% after 250 cycles at a current density of 1 C with an average coulombic efficiency higher than 99.7%.
Co-reporter:Shan Chen, Xiaowen Yu, Miao Zhang, Jiamin Cao, Yingru Li, Liming Ding and Gaoquan Shi
Journal of Materials Chemistry A 2015 vol. 3(Issue 36) pp:18380-18383
Publication Date(Web):06 Aug 2015
DOI:10.1039/C5TA04823K
An annealing-free hole transport layer based on oxygen deficient molybdenum oxide (MoO3−x) nanosheets was developed for polymer solar cells. It showed performance comparable to that of PEDOT:PSS. For better hole extraction, graphene oxide (GO) was introduced to form a GO/MoO3−x bilayer as a hole transport layer to further improve the device performance.
Co-reporter:Mingpeng Yu, Rui Li, Yue Tong, Yingru Li, Chun Li, Jong-Dal Hong and Gaoquan Shi
Journal of Materials Chemistry A 2015 vol. 3(Issue 18) pp:9609-9615
Publication Date(Web):23 Mar 2015
DOI:10.1039/C5TA00651A
A hair-derived carbon/sulfur composite was prepared via a facile melt-diffusion strategy and successively wrapped with reduced graphene oxide (rGO) sheets by electrostatic self-assembly. This composite was used as the sulfur electrode for lithium–sulfur (Li–S) batteries, exhibiting high capacity, good rate capability, and excellent cyclability. The electrode containing 69.0% (by weight, wt%) sulfur delivered an initial discharge capacity of 1113.2 mA h g−1 and 989.2 mA h g−1 after 300 cycles at a current density of 0.2 C with an average coulombic efficiency of 99.3%. Its capacity retention at 2 C was measured to be 62% with respect to the capacity achieved at 0.2 C. The high-performance of this electrode in Li–S batteries can be attributed to the porous carbon infrastructure, inherent nitrogen-doping and graphene protection. Taking into account the low-cost of raw materials and easy scalable processes, this work features a promising approach to prepare sulfur/carbon composites for high-performance Li–S batteries.
Co-reporter:Xiaowen Yu, Miao Zhang, Wenjing Yuan and Gaoquan Shi
Journal of Materials Chemistry A 2015 vol. 3(Issue 13) pp:6921-6928
Publication Date(Web):12 Feb 2015
DOI:10.1039/C5TA01034A
Water oxidation to evolve oxygen is the key step in water splitting and is related to a variety of energy systems. Here, we report a facile electrodeposition process to immobilize nickel–iron layered double hydroxide (Ni–Fe LDH) nanoplates on three-dimensional electrochemically reduced graphene oxide (3D-ErGO) for water oxidation. This Ni–Fe LDH/3D-ErGO electrode has a three-dimensional interpenetrating network with Ni–Fe nanoplates uniformly decorated on graphene sheets. It has an electrochemically active surface area (EASA) 3.3 times that of conventional planar electrodes. The open porous structure of this electrode also makes its EASA fully accessible to the electrolyte for water oxidation and easy release of oxygen gas. This electrode can be directly used for catalysing the oxygen evolution reaction (OER) in alkaline media without using a binder and conductive additive, exhibiting a small overpotential of 0.259 V and a low Tafel slope of 39 mV dec−1. It outperforms the precious IrO2 catalyst in activity, kinetics, and electrochemical stability.
Co-reporter:Zhibing Tan, Miao Zhang, Chun Li, Shiyong Yu, and Gaoquan Shi
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 27) pp:15010
Publication Date(Web):June 26, 2015
DOI:10.1021/acsami.5b04093
Artificial nacre-like composite films of graphene oxide (GO) with a variety of commercially available water-soluble polymers were fabricated by a gel–film transformation (GFT) technique. The blending of a polymer into the aqueous dispersion of GO can modulate the interaction between GO sheets. Typically, the attraction force between polymer and GO sheets overcomes the dominant hydration and electrostatic repulsive forces between GO sheets, promoting the gelation of GO. Cast drying the resultant GO hydrogel containing small amounts of polymer (1–20 wt % relative to GO depending on the intrinsic structures of polymers) generates layered GO composite films with tensile strengths over 200 MPa and failure strains larger than 3.0%, which are higher than those of natural nacre and most nacre-like GO films. These results indicate that GO/polymer composite hydrogels are excellent precursors for nacre-like GO films and that the GFT approach is a general route toward the large-scale fabrication of nacre-like GO films with unique combinations of high strength and high toughness.Keywords: artificial nacre; gelation; graphene oxide; hierarchical structure; mechanical properties;
Co-reporter:Zhe Ji, Ji Chen, Liang Huang and Gaoquan Shi
Chemical Communications 2015 vol. 51(Issue 14) pp:2806-2809
Publication Date(Web):07 Jan 2015
DOI:10.1039/C4CC09144B
On the basis of the Diels–Alder reaction of graphite and tetracyanoethylene, graphite has been mechanically exfoliated into graphene adducts in a yield up to 38%. The graphene adduct can restore its conjugated structure via retro-Diels–Alder reaction under mild conditions, exhibiting a high conductivity of 1035 S m−1.
Co-reporter:Ji Chen, Yingru Li, Liang Huang, Chun Li, Gaoquan Shi
Carbon 2015 Volume 81() pp:826-834
Publication Date(Web):January 2015
DOI:10.1016/j.carbon.2014.10.033
Graphite flakes with sizes in the range of 3–20 μm can be completely converted into single-layer graphene oxide (GO) with a high yield of 171 ± 4% via an improved Hummers method. This yield is much higher than that (110 ± 3%) from larger graphite flakes with sizes of 10–100 μm. The structures, qualities and size distributions of the GO sheets prepared from both graphite precursors are nearly identical. More importantly, in the case of using small graphite flakes, the GO dispersion can be directly purified without the requirement of centrifugation to remove unoxidized residuals. Considering the high yield, simplified purification procedure, and high-quality of GO, the modification of using graphite flakes with small sizes is an important step towards the mass-production of GO at industrial scale.
Co-reporter:Bowen Yao, Chun Li, Jun Ma and Gaoquan Shi
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 29) pp:19538-19545
Publication Date(Web):30 Jun 2015
DOI:10.1039/C5CP02853A
Graphene oxide frameworks (GOFs) have attracted a great deal of attention because of their unique functional building blocks, and tunable structures and properties. Herein, a series of porphyrin-based GOFs with crystalline lamellar structures were synthesized via esterification between boronic acid groups of porphyrins and hydroxyl groups of GO sheets. These GOFs have ultra-large d-spacings of up to 26.0 Å, and they were reduced by facile electrochemical reduction. The resulting reduced GOFs (rGOFs) can be used as catalysts for oxygen reduction reaction (ORR). Electrochemical reduction improved the conductivities of GOFs, accelerating the charge transfer of ORR. The rGOF with Co-porphyrin showed the most positive onset potential of ORR at 0.89 V (vs. RHE, reversible hydrogen electrode), while the rGOF with Fe-porphyrin exhibited the highest catalytic efficiency through an approximately four-electron process. This study provides a new insight for the development of GOFs using multi-functional macrocyclic molecules, revealing their promising applications in electrocatalysts.
Co-reporter:Xiluan Wang and Gaoquan Shi
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 43) pp:28484-28504
Publication Date(Web):06 Oct 2015
DOI:10.1039/C5CP05212B
Pristine graphene and chemically modified graphenes (CMGs, e.g., graphene oxide, reduced graphene oxide and their derivatives) can react with a variety of chemical substances. These reactions have been applied to modulate the structures and properties of graphene materials, and to extend their functions and practical applications. This perspective outlines the chemistry of graphene, including functionalization, doping, photochemistry, catalytic chemistry, and supramolecular chemistry. The mechanisms of graphene related reactions will be introduced, and the challenges in controlling the chemical reactions of graphene will be discussed.
Co-reporter:Qiang Liu, Miao Zhang, Liang Huang, Yingru Li, Ji Chen, Chun Li, and Gaoquan Shi
ACS Nano 2015 Volume 9(Issue 12) pp:12320
Publication Date(Web):October 20, 2015
DOI:10.1021/acsnano.5b05609
Reduced graphene oxide (rGO) ribbons with arbitrary lengths were prepared by dry spinning of the hydrogels of graphene oxide (GO) formed via thermal annealing GO dispersions, and followed by chemical reduction. These rGO ribbons are flexible, having ultrahigh tensile strengths of 582 ± 17 MPa, ultrahigh fracture energies of 18.29 ± 2.47 MJ m–3, high conductivities of 662 ± 41 S cm–1, and an extremely large breakdown current density of about 11 500 A cm–2. Strain sensors based on the meshes of these ribbons showed sensitive recoverable responses to different tensile strains with excellent cycling stability, promising for the applications in wearable devices.Keywords: dry spinning; hydrogel; reduced graphene oxide; ribbon; strain sensor;
Co-reporter:Yingru Li;Ji Chen;Liang Huang;Chun Li
Advanced Electronic Materials 2015 Volume 1( Issue 5) pp:
Publication Date(Web):
DOI:10.1002/aelm.201500004
Co-reporter:Liang Huang; Miao Zhang; Chun Li
The Journal of Physical Chemistry Letters 2015 Volume 6(Issue 14) pp:2806-2815
Publication Date(Web):June 24, 2015
DOI:10.1021/acs.jpclett.5b00914
In comparison with traditional chemical separation processes, membrane separation is much simpler and more efficient. An ideal membrane for molecular separation should be as thin as possible to maximize its solvent flux, be mechanically robust to prevent it from fracture, and have well-defined pore sizes to guarantee its selectivity. Graphene is an excellent platform for developing size-selective membranes because of its atomic thickness, high mechanical strength, and chemical inertness. In this Perspective, we review the recent advancements on the fabrication of nanoporous graphene membranes and graphene oxide membranes (GOMs) for molecular separation. The methods of fabricating these membranes are summarized, and the mechanisms of molecular separation based on these two types of graphene membranes are compared. The challenges of synthesizing and transferring large-area nanoporous graphene membranes and engineering the performances of GOMs are discussed.
Co-reporter:Chun Li
Advanced Materials 2014 Volume 26( Issue 24) pp:3992-4012
Publication Date(Web):
DOI:10.1002/adma.201306104
Chemically modified graphene (CMG) materials have been extensively studied because of their unique structures, excellent properties, and potential applications in energy storage and conversion, catalysis, and environment remediation. However, the unique two-dimensional structure and amphiphilicity make CMG sheets easily restack into irregular aggregates, which greatly reduces their accessible surface area, and thereby deteriorates their performance in practical applications. To exploit their inherent properties fully, CMGs usually have to be fabricated or assembled into functional gels with desired three-dimensional (3D) interconnected porous microstructures. In this review, we summarize the recent achievements in the synthesis of CMG-based functional gels, including hydrogels, organogels, aerogels, and their composites. The mechanisms of gel formation and the applications of these functional gels will also be discussed.
Co-reporter:Yingru Li;Ji Chen;Liang Huang;Chun Li;Jong-Dal Hong
Advanced Materials 2014 Volume 26( Issue 28) pp:4789-4793
Publication Date(Web):
DOI:10.1002/adma.201400657
Co-reporter:Miao Zhang;Liang Huang;Ji Chen;Chun Li
Advanced Materials 2014 Volume 26( Issue 45) pp:7588-7592
Publication Date(Web):
DOI:10.1002/adma.201403322
Co-reporter:Wenjing Yuan, Ji Chen, Gaoquan Shi
Materials Today 2014 Volume 17(Issue 2) pp:77-85
Publication Date(Web):March 2014
DOI:10.1016/j.mattod.2014.01.021
Nanoporous graphene (NPG) materials have been widely studied and exploited to open the band gap, increase the specific surface area and dispersibility, and/or improve the optical, catalytic and sensing properties of pristine graphene. This review summarizes the recent advancements on the synthesis of NPGs and their applications in field effect transistors (FETs), sensors, electrochemical capacitors, nucleic acid analysis and molecular sieving.
Co-reporter:Qinqin Zhou, Yingru Li, Liang Huang, Chun Li and Gaoquan Shi
Journal of Materials Chemistry A 2014 vol. 2(Issue 41) pp:17489-17494
Publication Date(Web):27 Aug 2014
DOI:10.1039/C4TA03639E
We report an electrochemical co-deposition method to prepare three-dimensional (3D) porous composites of reduced graphene oxide (rGO) and polyaniline (PANI) with pores vertically oriented on the surfaces of current collectors and used as an electrode material for electrochemical capacitors (ECs). These composites showed much higher areal specific capacitances and greatly improved rate capability than those of PANI. Typically, the rGO/PANI composite film with a thickness of 150 μm exhibited a high areal specific capacitance (Ca, 67.2 mF cm−2), small relaxation time constant (τ0, 316 ms) and good electrochemical stability, promising for the fabrication of a high-rate EC.
Co-reporter:Mingpeng Yu, Wenjing Yuan, Chun Li, Jong-Dal Hong and Gaoquan Shi
Journal of Materials Chemistry A 2014 vol. 2(Issue 20) pp:7360-7366
Publication Date(Web):21 Feb 2014
DOI:10.1039/C4TA00234B
A graphene–sulfur (G–S) composite was conformally coated with an ultrathin Al2O3 film via atomic layer deposition (ALD) and used as the cathode of a lithium–sulfur (Li–S) battery. The G–S composite cathode with an ALD-Al2O3 coating delivered a high specific capacity of 646 mA h g−1 after 100 charge–discharge cycles at 0.5 C, and this value is about twice that of the bare G–S composite. The rate capability and coulombic efficiency of the G–S composite electrode were also greatly increased. The ALD-Al2O3 coating worked as an artificial barrier to suppress the dissolution of polysulfides and alleviate the shuttle effect; thus, it effectively improved the performance of a G–S composite cathode in a Li–S battery.
Co-reporter:Mingpeng Yu, Aiji Wang, Yinshu Wang, Chun Li and Gaoquan Shi
Nanoscale 2014 vol. 6(Issue 19) pp:11419-11424
Publication Date(Web):05 Aug 2014
DOI:10.1039/C4NR02576H
Atomic layer deposition (ALD) was applied to deposit ZnO on graphene aerogel, and this composite was used as an anode material for lithium ion batteries. This electrode material was further modified by an ultrathin Al2O3 layer via ALD to stabilize its electrochemical stability. These two metal oxides were uniformly immobilized on graphene frameworks, and the Al2O3 coating strongly improved the electrochemical performances of ZnO–graphene aerogel composite anodes. Particularly, the composite with 10 ALD cycles of Al2O3 coating (denoted as ZnO–G-10) exhibited a high initial discharge capacity of 1513 mA h g−1 and maintained a reversible capacity of 490 mA h g−1 after 100 cycles at a current density of 100 mA g−1. Furthermore, the capacity retention rate increased from 70% to 90% in comparison with its uncoated counterpart after 100 cycles. The ZnO–G-10 anode also showed good rate-capability, delivering a discharge capacity of 415 mA h g−1 at 1000 mA g−1. The improved electrochemical performance is attributed to the formation of an artificial solid electrolyte interphase layer, stabilizing ZnO and the electrolyte by preventing the aggregation of Zn/ZnO nanograins and the side reaction that would cause the degradation of anodes.
Co-reporter:Liang Huang, Chun Li and Gaoquan Shi
Journal of Materials Chemistry A 2014 vol. 2(Issue 4) pp:968-974
Publication Date(Web):08 Nov 2013
DOI:10.1039/C3TA14511E
We report the fabrication of electrochemical capacitors (ECs) with high energy and power densities based on the compact reduced graphene oxide (rGO)/poly(vinyl pyrrolidone) (PVP) composite films. In these ECs, rGO/PVP composite films were directly used as the electrode material without blending any binders or conductive additives because of their high mechanical strength (121.5 ± 10.8 MPa) and electrical conductivity (247.9 S m−1). The solid-state ECs based on the rGO/PVP composite containing 55% rGO (by weight) showed high gravimetric and volumetric specific capacitances, good rate-capability, excellent flexibility and satisfactory electrochemical stability. Furthermore, the EC based on the composite film containing 71% (by weight) of rGO with an organic electrolyte exhibited a high power density (40 W cm−3) and a high energy density (2.5 mW h cm−3) at a current density of 1 A g−1 by taking account of the volumes of its electrodes and separator.
Co-reporter:Wenjing Yuan, Liang Huang, Qinqin Zhou, and Gaoquan Shi
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 19) pp:17003
Publication Date(Web):September 10, 2014
DOI:10.1021/am504616c
Reduced graphene oxide (rGO) sheets were self-assembled onto the surfaces of electrospun polymer nanofibers to form an ultrathin coating. These rGO/polymer composite nanofibers were used to fabricate nitrogen dioxide (NO2) sensor. This sensor can be performed at room temperature, and it exhibited a high sensitivity of 1.03 ppm–1 with excellent selectivity and good reversibility. Furthermore, the limit of detection was experimentally measured to be as low as 150 ppb, and this value is much lower than the threshold exposure limit proposed by American Conference of Governmental Industrial Hygienists (200 ppb).Keywords: electrospinning; gas sensor; nitrogen dioxide; reduced graphene oxide; self-assembly
Co-reporter:Yiqing Sun, William D. Chemelewski, Sean P. Berglund, Chun Li, Huichao He, Gaoquan Shi, and C. Buddie Mullins
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 8) pp:5494
Publication Date(Web):March 26, 2014
DOI:10.1021/am405628r
We report the growth of well-defined antimony-doped tin oxide (ATO) nanorods as a conductive scaffold to improve hematite’s photoelectrochemical water oxidation performance. The hematite grown on ATO exhibits greatly improved performance for photoelectrochemical water oxidation compared to hematite grown on flat fluorine-doped tin oxide (FTO). The optimized photocurrent density of hematite on ATO is 0.67 mA/cm2 (0.6 V vs Ag/AgCl), which is much larger than the photocurrent density of hematite on flat FTO (0.03 mA/cm2). Using H2O2 as a hole scavenger, it is shown that the ATO nanorods indeed act as a useful scaffold and enhanced the bulk charge separation efficiency of hematite from 2.5% to 18% at 0.4 V vs Ag/AgCl.Keywords: Fe2O3; nanorod scaffold; PEC; photoelectrochemistry; water oxidation; water splitting;
Co-reporter:Xiaowen Yu, Kaixuan Sheng and Gaoquan Shi
Analyst 2014 vol. 139(Issue 18) pp:4525-4531
Publication Date(Web):20 Jun 2014
DOI:10.1039/C4AN00604F
Electrochemical detection of dopamine plays an important role in medical diagnosis. In this paper, we report a three-dimensional (3D) interpenetrating graphene electrode fabricated by electrochemical reduction of graphene oxide for selective detection of dopamine. This electrochemically reduced graphene oxide (ErGO) electrode was used directly without further functionalization or blending with other functional materials. This electrode can efficiently lower the oxidation potential of ascorbic acid; thus, it is able to selectively detect dopamine in the presence of ascorbic acid and uric acid. The ErGO-based biosensor exhibited a linear response towards dopamine in the concentration range of 0.1–10 μM with a low detection limit of 0.1 μM. Furthermore, this electrode has good reproducibility and environmental stability, and can be used to analyse real samples.
Co-reporter:Xiluan Wang, Chun Li and Gaoquan Shi
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 21) pp:10142-10148
Publication Date(Web):14 Jan 2014
DOI:10.1039/C3CP54058H
Platinum (Pt)-based catalysts used in direct methanol fuel cells (DMFCs) usually suffer from low catalytic activity, slow kinetics of methanol oxidation and poor electrochemical stability. This is mainly due to the toxic effect of carbon monoxide and inefficient use of the Pt catalysts. To address these problems, we immobilized Pt nanoparticles with diameters of 4–6 nm onto the three-dimensional (3D) interpenetrating graphene networks (graphene hydrogel or G-Gel) deposited in the micropores of nickel foam (NF). In this Pt/G-Gel/NF composite catalyst, nearly all the Pt nanoparticles are accessible to methanol and can be efficiently used for electrocatalyzation. It showed excellent electrochemical stability and an activity 2.6 times that of a conventional Pt/reduced graphene oxide (Pt/rGO) composite catalyst. Furthermore, the rate of methanol electro-oxidation at the Pt/G-Gel/NF catalyst can be about 27 times that at the Pt/rGO catalyst, making it applicable for fabricating DMFCs with high current and/or power outputs.
Co-reporter:Chun Li, Gaoquan Shi
Journal of Photochemistry and Photobiology C: Photochemistry Reviews 2014 Volume 19() pp:20-34
Publication Date(Web):June 2014
DOI:10.1016/j.jphotochemrev.2013.10.005
•The methodology of preparing CNT composites for fluorescent sensors is reviewed.•Recent studies on modulating the NIR fluorescence of SWCNT for sensors.•Methods to construct fluorescent sensors using CNT as a quencher are summarized.The one-dimensional π-conjugated structure endows carbon nanotube (CNT) with large specific surface area and excellent photophysical properties, thus providing a unique platform for the development of chemo- and biosensors based on optical signal output. Although CNT acts as an optical signal transducer, it does not own any intrinsic ability for the selective binding and recognition of analytes. Thus, hybridization of CNTs with functional components that specifically recognize various chemical and biomolecular analytes is often necessary in the preparation of CNT-based sensors. In this review, we summarize preparation and photophysical properties of CNT-based composites, and then highlight on fluorescence sensors based on CNT-composites. These composite sensors integrate the signal transduction property of CNT and the recognition properties of the hybridized functional components. The functional components selectively bind with the target analytes, whereas, CNTs transform the binding events into output signals detectable using spectrofluorometer. Particularly, we highlight on recent progress in the chemical and bimolecular sensors based on near-infrared fluorescence of semiconducting single-walled CNT (SWCNT) and the excellent fluorescence quenching ability of CNTs over conventional organic quenchers.
Co-reporter:Wenjing Yuan;Anran Liu;Liang Huang;Chun Li
Advanced Materials 2013 Volume 25( Issue 5) pp:766-771
Publication Date(Web):
DOI:10.1002/adma.201203172
Co-reporter:Liang Huang, Chun Li, Wenjing Yuan and Gaoquan Shi
Nanoscale 2013 vol. 5(Issue 9) pp:3780-3786
Publication Date(Web):15 Mar 2013
DOI:10.1039/C3NR00196B
Composite films of graphene oxide (GO) sheets and silk fibroin (SF) with layered structures have been prepared by facile solution casting of SF–GO hydrogels. The as-prepared composite film containing 15% (by weight, wt%) of SF shows a high tensile strength of 221 ± 16 MPa and a failure strain of 1.8 ± 0.4%, which partially surpass those of natural nacre. Particularly, this composite film also has a high modulus of 17.2 ± 1.9 GPa. The high mechanical properties of this composite film can be attributed to its high content of GO (85 wt%), compact layered structure and the strong hydrogen bonding interaction between SF chains and GO sheets.
Co-reporter:Qinqin Zhou, Jian Gao, Chun Li, Ji Chen and Gaoquan Shi
Journal of Materials Chemistry A 2013 vol. 1(Issue 32) pp:9196-9201
Publication Date(Web):06 Jun 2013
DOI:10.1039/C3TA11438D
We report the preparation of composite organogels of reduced graphene oxide (rGO) and activated carbon (AC) by a solvothermal reaction and their application as electrodes of electrochemical capacitors (ECs). In these organogels, rGO sheets are assembled into a 3-dimensional (3D) framework for encapsulating AC particles. The 3D interconnected rGO network increased the electrical conductivity and the AC component provided high specific surface areas (SSAs) for the composite organogels. These composite organogels also have stable mechanical properties and can be directly used as electrodes of ECs without using any binding agent and conducting additive. In a practical two-electrode system, the specific capacitance of the ECs based on the composite organogels was tested to be 116.5 ± 2.2 F g−1 at a current density of 1 A g−1 in an organic electrolyte of propylene carbonate (PC) containing 1 M tetraethylammonium tetrafluorobromate (TEABF4). These ECs also exhibited a high energy density of 12.5 Wh kg−1 even at a high power density of 6216 W kg−1. They also showed a much larger volumetric specific capacitance compared with that of the EC based on rGO organogel and a much higher specific capacitance and rate capability than those of the AC-based EC.
Co-reporter:Peihui Luo, Zhe Ji, Chun Li and Gaoquan Shi
Nanoscale 2013 vol. 5(Issue 16) pp:7361-7367
Publication Date(Web):10 Jun 2013
DOI:10.1039/C3NR02156D
Chemical modification is an important technique to modulate the chemical and optical properties of graphene quantum dots (GQDs). In this paper, we report a versatile diazonium chemistry method to graft aryl groups including phenyl, 4-carboxyphenyl, 4-sulfophenyl and 5-sulfonaphthyl to GQDs via Gomberg–Bachmann reaction. The aryl-modified GQDs are nanocrystals with lateral dimensions in the range of 2–4 nm and an average thickness lower than 1 nm. Upon chemical modification with aryl groups, the photoluminescence (PL) bands of GQDs were tuned in the range of 418 and 447 nm, and their fluorescence quantum yields (QYs) were increased for up to about 6 times. Furthermore, the aryl-modified GQDs exhibited stable PL (both intensity and peak position) in a wide pH window of 1–11. The mechanism of improving the PL properties of GQDs by aryl-modification was also discussed.
Co-reporter:Wenjing Yuan and Gaoquan Shi
Journal of Materials Chemistry A 2013 vol. 1(Issue 35) pp:10078-10091
Publication Date(Web):26 Jun 2013
DOI:10.1039/C3TA11774J
Graphene materials have been widely explored for the fabrication of gas sensors because of their atom-thick two-dimensional conjugated structures, high conductivity and large specific surface areas. This feature article summarizes the recent advancements on the synthesis of graphene materials for this purpose and the techniques applied for fabricating gas sensors. The effects of the compositions, structural defects and morphologies of graphene-based sensing layers and the configurations of sensing devices on the performances of gas sensors will also be discussed.
Co-reporter:Yingru Li, Kaixuan Sheng, Wenjing Yuan and Gaoquan Shi
Chemical Communications 2013 vol. 49(Issue 3) pp:291-293
Publication Date(Web):14 Nov 2012
DOI:10.1039/C2CC37396C
A fibre-shaped solid electrochemical capacitor based on electrochemically reduced graphene oxide has been fabricated, exhibiting high specific capacitance and rate capability, long cycling life and attractive flexibility.
Co-reporter:Ji Chen, Bowen Yao, Chun Li, Gaoquan Shi
Carbon 2013 Volume 64() pp:225-229
Publication Date(Web):November 2013
DOI:10.1016/j.carbon.2013.07.055
An improved Hummers method without using NaNO3 can produce graphene oxide nearly the same to that prepared by conventional Hummers method. This modification does not decrease the yield of product, eliminating the evolution of NO2/N2O4 toxic gasses and simplifying the disposal of waste water because of the inexistence of Na+ and NO3− ions. For the first time, we also developed a prototype method of post-treating the waste water collected from the systems of synthesizing and purifying graphene oxide. The content of Mn2+ ions in the purified waste water was measured to be lower than the guideline value for drinking water.
Co-reporter:Yiqing Sun, Shiqi Wang, Chun Li, Peihui Luo, Lei Tao, Yen Wei and Gaoquan Shi
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 24) pp:9907-9913
Publication Date(Web):24 Apr 2013
DOI:10.1039/C3CP50691F
We report an improved Hummers method for synthesizing graphene quantum dots (GQDs) by directly oxidizing and etching graphite powders. The yield of GQDs is as high as 63 ± 7% (by weight, wt%), suggesting this technique is suitable for producing GQDs on a large scale. The GQDs are nanocrystals with lateral dimensions in the range of 2–4 nm and an average thickness of around 1.3 nm. The emission peaks of as-prepared GQDs can be tuned in the range of 440 to 510 nm by varying the reaction conditions. Their fluorescence quantum yields were tested to be around 1%, which could be further increased to about 3% by hydrothermal treatment. These GQDs have low cytotoxicity and excellent biocompatibility, indicating that they are promising for biological applications.
Co-reporter:Yiqing Sun
Journal of Polymer Science Part B: Polymer Physics 2013 Volume 51( Issue 4) pp:231-253
Publication Date(Web):
DOI:10.1002/polb.23226
Abstract
Graphene has wide potential applications in energy-related systems, mainly because of its unique atom-thick two-dimensional structure, high electrical or thermal conductivity, optical transparency, great mechanical strength, inherent flexibility, and huge specific surface area. For this purpose, graphene materials are frequently blended with polymers to form composites, especially when fabricating flexible devices. Graphene/polymer composites have been explored as electrodes of supercapacitors or lithium ion batteries, counter electrodes of dye-sensitized solar cells, transparent conducting electrodes and active layers of organic solar cells, catalytic electrodes, and polymer electrolyte membranes of fuel cells. In this review, we summarize the recent advances on the synthesis and applications of graphene/polymer composites for energy applications. The challenges and prospects in this field have also been discussed. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Co-reporter:Cancan Huang, Chun Li and Gaoquan Shi
Energy & Environmental Science 2012 vol. 5(Issue 10) pp:8848-8868
Publication Date(Web):20 Aug 2012
DOI:10.1039/C2EE22238H
Graphene has a unique atom-thick two-dimensional (2D) structure, high conductivity and charge mobility, huge specific surface area, excellent mechanical, thermal and electrical properties. Thus, it has been regarded as an important component for functional materials, especially for developing a variety of catalysts. In this review, we summarize the recent advancements in synthesizing graphene based new catalysts, and their applications in organic synthesis, sensors, environmental protection and energy related systems.
Co-reporter:Ji Chen;Kaixuan Sheng;Peihui Luo;Chun Li
Advanced Materials 2012 Volume 24( Issue 33) pp:4569-4573
Publication Date(Web):
DOI:10.1002/adma.201201978
Co-reporter:Li Zhang, Chun Li, Anran Liu and Gaoquan Shi
Journal of Materials Chemistry A 2012 vol. 22(Issue 17) pp:8438-8443
Publication Date(Web):19 Mar 2012
DOI:10.1039/C2JM16552J
Graphene oxide/polypyrene (GO/PPr) composite films were prepared by electrochemical co-deposition of GO and PPr from the organic electrolyte of propylene carbonate (PC). The effects of the GO content in the electrolyte and the deposition charge density on the formation of GO/PPr composite films were studied. Blending with GO improved the mechanical properties of the powdery PPr and gave the composite a continuous and porous morphology with an uninterrupted conducting phase. A chemoresistor-type vapor sensor based on the GO/PPr composite film demonstrated a fast, linear and reversible response to toluene with a high normalized sensitivity of 9.87 × 10−4 ppm−1. The mechanism of sensing the organic vapors with the GO/PPr composite film was also discussed.
Co-reporter:Chun Li and Gaoquan Shi
Nanoscale 2012 vol. 4(Issue 18) pp:5549-5563
Publication Date(Web):26 Jul 2012
DOI:10.1039/C2NR31467C
Graphene has been widely explored for applications in electronics, sensors, actuators, catalysis and bio- or energy related systems. For these purposes, graphene materials usually have to be fabricated or assembled into desired micro-/nano-architectures for tuning and/or controlling their electrical, optical, mechanical, chemical or electrochemical properties. In this feature article, we review recent achievements in the studies of three-dimensional (3D) graphene architectures. The methodology for preparing these 3D graphene micro-/nano-architectures and their potential applications have been summarized.
Co-reporter:Yiqing Sun, Chun Li and Gaoquan Shi
Journal of Materials Chemistry A 2012 vol. 22(Issue 25) pp:12810-12816
Publication Date(Web):30 Apr 2012
DOI:10.1039/C2JM31525D
Nanoporous nitrogen doped carbon was used to modify the surfaces of graphene sheets by carbonizing a mixture of graphene oxide and phenol–melamine–formaldehyde (PMF) pre-polymer in the presence of a soft template (F127). The resulting graphene based composite sheets (G-PMFs) have a sandwich structure with one graphene layer and two nanoporous nitrogen-doped carbon layers. G-PMFs have large specific surface areas of 190 to 630 m2 g−1 and exhibited high electrocatalytic activity, good durability and high selectivity for the oxygen reduction reaction. The performance of the Zn–air fuel cell with a G-PMF anode was tested and found to be comparable to that of the Zn–air cell with a commercial Pt/C anode. Thus, these metal-free catalysts are promising for applications in practical fuel cells.
Co-reporter:Peihui Luo, Chun Li and Gaoquan Shi
Physical Chemistry Chemical Physics 2012 vol. 14(Issue 20) pp:7360-7366
Publication Date(Web):02 Apr 2012
DOI:10.1039/C2CP40767A
Gold@carbon dots composite nanoparticles (Au@CDs) with ultrathin carbon dot (CD) shells of ca. 2 nm were prepared by reducing HAuCl4 with CDs at 100 °C. By adjusting the feeding mass ratio of HAuCl4 to CDs, the average diameters of Au@CDs can be modulated from 8 to 44 nm. The suspension of Au@CDs with an average diameter of ca. 24 nm was applied as a substrate for surface enhanced Raman scattering (SERS) and it exhibited a higher SERS effect for rhodamine 6G (Rh6G) than the suspension of pure Au nanoparticles with nearly the same size. The excellent SERS effect of Au@CDs is mainly attributed to their improved capability of adsorbing the aromatic probe molecules.
Co-reporter:Xiluan Wang, Hua Bai, Yuying Jia, Linjie Zhi, Liangti Qu, Yuxi Xu, Chun Li and Gaoquan Shi
RSC Advances 2012 vol. 2(Issue 5) pp:2154-2160
Publication Date(Web):19 Jan 2012
DOI:10.1039/C2RA00765G
Composite crystals of calcium carbonate (CaCO3) and graphene with hexagonal plate or ring, dendritic and rhombohedral shapes were synthesized by the hydrothermal reaction of calcium acetate and urea in the presence of graphene oxide (GO) sheets. Their crystal structures were characterized to be vaterite, aragonite and calcite, respectively. In this case, the hydrothermally reduced graphene oxide (rGO) acted as an atom-thick, two-dimensional template for controlling the nucleation and growth of the CaCO3 crystals. The vaterite CaCO3 composite crystals (VCCs) were used as a filler of poly(vinyl alcohol) (PVA) to form a composite with a nacre-like structure. The Young's modulus and tensile strength of PVA/45 wt% VCC were tested to be 34.1 ± 2.5 GPa and 165 ± 6 MPa, respectively.
Co-reporter:Huhu Cheng, Yang Zhao, Yueqiong Fan, Xuejun Xie, Liangti Qu, and Gaoquan Shi
ACS Nano 2012 Volume 6(Issue 3) pp:2237
Publication Date(Web):February 13, 2012
DOI:10.1021/nn204289t
Graphene quantum dots (GQDs), single or few-layer graphenes with a size of only several nanometers, are a new type of quantum dots (QDs) with unique properties. The assembly of QDs in a geometrically well-defined fashion opens up opportunities to obtain access to the full potential of assembled QDs by virtue of the collective properties of the ensembles. In the current study, we present the well-organized assembly of zero-dimensional (0D) functional GQDs into 1D nanotube (NT) arrays and demonstrate their remarkable potential as a new metal-free platform for efficient surface-enhanced Raman scattering (SERS) applications. The hierarchically porous 1D nanotube structure of 0D GQDs has been prepared by electrophoresis deposition within a nanoporous AAO template. On the basis of the unique porous nanotube architecture of GQDs, the GQD-NTs could ensure a more efficient charge transfer between the target molecules and the GQDs and thus produce much stronger SERS effect, exceeding that on flat graphene sheets. The unique architecture of 1D nanotubes of 0D GQDs provides a new point of view for designing and fabricating SERS substrates.Keywords: assembly; graphene quantum dots; nanotube; surface-enhanced Raman scattering; template
Co-reporter:Anran Liu, Wenjing Yuan, Gaoquan Shi
Thin Solid Films 2012 Volume 520(Issue 19) pp:6307-6312
Publication Date(Web):31 July 2012
DOI:10.1016/j.tsf.2012.06.039
A tri-layer electrochemical actuator was fabricated by the electrodeposition of polypyrrole (PPy) onto a sulfonated graphene (SG)/reduced graphene oxide (RGO) bi-layer film. In this actuator, PPy and RGO were acted as actuation and conductive inert layers, respectively. The SG layer was used to enhance the interfacial interactions. The tri-layer actuator exhibited high and stable actuating performance for over 1000 actuation cycles, and the lifetime of the actuator was tested to be about 5000 cycles. The bending angle of the actuator is larger than 360° and its movement rate was higher than 150° s− 1 under a driving potential of 1.0 V versus saturated calomel electrode. Furthermore, the low weight density of graphene based supporting layer greatly lowered the energy or charge consuming of the actuator during electrochemical actuation.Highlights► Actuator based on polypyrrole (PPy)/graphene composite film was fabricated. ► The actuator exhibits fast and large actuations with low energy consuming. ► The actuator has a lifetime 2.5 times that of conventional PPy/Au actuator.
Co-reporter:Yiqing Sun, Qiong Wu and Gaoquan Shi
Energy & Environmental Science 2011 vol. 4(Issue 4) pp:1113-1132
Publication Date(Web):05 Feb 2011
DOI:10.1039/C0EE00683A
Graphene, a one-atom layer of graphite, possesses a unique two-dimensional (2D) structure, high conductivity and charge carrier mobility, huge specific surface area, high transparency and great mechanical strength. Thus, it is expected to be an ideal material for energy storage and conversion. During the past several years, a variety of graphene based materials (GBMs) have been successfully prepared and applied in supercapacitors, lithium ion batteries, water splitting, electrocatalysts for fuel cells, and solar cells. In this review, we will summarize the recent advances in the synthesis and applications of GBMs in these energy related systems. The challenges and prospects of graphene based new energy materials are also discussed.
Co-reporter:Hua Bai;Chun Li
Advanced Materials 2011 Volume 23( Issue 9) pp:1089-1115
Publication Date(Web):
DOI:10.1002/adma.201003753
Abstract
Graphene, a one-atom layer of graphite, possesses a unique two-dimensional structure and excellent mechanical, thermal, and electrical properties. Thus, it has been regarded as an important component for making various functional composite materials. Graphene can be prepared through physical, chemical and electrochemical approaches. Among them, chemical methods were tested to be effective for producing chemically converted graphene (CCG) from various precursors (such as graphite, carbon nanotubes, and polymers) in large scale and at low costs. Therefore, CCG is more suitable for synthesizing high-performance graphene based composites. In this progress report, we review the recent advancements in the studies of the composites of CCG and small molecules, polymers, inorganic nanoparticles or other carbon nanomaterials. The methodology for preparing CCG and its composites has been summarized. The applications of CCG-based functional composite materials are also discussed.
Co-reporter:Hua Bai;Chun Li
Advanced Materials 2011 Volume 23( Issue 9) pp:
Publication Date(Web):
DOI:10.1002/adma.201190025
Abstract
Graphene, a one-atom layer of graphite, possesses a unique two-dimensional structure and excellent mechanical, thermal, and electrical properties. Thus, it has been regarded as an important component for making various functional composite materials. Graphene can be prepared through physical, chemical and electrochemical approaches. Among them, chemical methods were tested to be effective for producing chemically converted graphene (CCG) from various precursors (such as graphite, carbon nanotubes, and polymers) in large scale and at low costs. Therefore, CCG is more suitable for synthesizing high-performance graphene based composites. In this progress report, we review the recent advancements in the studies of the composites of CCG and small molecules, polymers, inorganic nanoparticles or other carbon nanomaterials. The methodology for preparing CCG and its composites has been summarized. The applications of CCG-based functional composite materials are also discussed.
Co-reporter:Xiluan Wang ; Hua Bai
Journal of the American Chemical Society 2011 Volume 133(Issue 16) pp:6338-6342
Publication Date(Web):March 30, 2011
DOI:10.1021/ja200218y
Graphene oxide (GO) sheets prepared by Hummers’ method have been separated into two portions with large (f1) or small (f2) lateral dimensions from their aqueous dispersion. This method is based on the selective precipitation of GO sheets with lateral dimensions mostly (>90%) larger than 40 μm2 at a pH value of 4.0 because of their larger hydrophobic planes and fewer hydrophilic oxygenated groups. The hydrazine reduced Langmuir−Blodgett (LB) films of f1 showed much higher conductivities than those of f2. Furthermore, the thin film of f1 prepared by filtration exhibited a smaller d-space and much higher tensile strength and modulus than those of f2 films. The one-step size fractionation method reported here is simple, cheap, efficient, and environmentally friendly, which can be used for the size fractionation of GO sheets in large scale.
Co-reporter:Yuxi Xu, Kaixuan Sheng, Chun Li and Gaoquan Shi
Journal of Materials Chemistry A 2011 vol. 21(Issue 20) pp:7376-7380
Publication Date(Web):09 Apr 2011
DOI:10.1039/C1JM10768B
Mildly oxidized graphene oxide (MOGO) was achieved by chemical exfoliation of graphite through a modified Hummers' method. The MOGO is not only able to be stably dispersed in water at a high concentration (1 mg mL−1), but also preserves the highly crystalline structure of the conjugated carbon framework. Thus, the MOGO can be used as a low-defect precursor to prepare highly conductive graphene by chemical reduction. The electrical conductivity of hydrazine or hydriodic acid reduced MOGO was measured to be 169 or 405 S cm−1. This value is about 3 times that of the chemically converted graphene (CCG) prepared by reducing the conventional graphene oxide via Hummers' method with the same reducing agent. This work not only develops a facile route to high-throughput preparation of processable high-quality CCG, but also provides a deeper understanding of the crucial influence of the degree of oxidation of graphene oxide on the electrical properties of its reduced product.
Co-reporter:Yuxi Xu and Gaoquan Shi
Journal of Materials Chemistry A 2011 vol. 21(Issue 10) pp:3311-3323
Publication Date(Web):21 Oct 2010
DOI:10.1039/C0JM02319A
Chemically modified graphenes (CMGs) are unique building blocks for “bottom up” nanotechnology because of their single-atom thickness, two-dimensional conjugated structure, and exceptional physical and chemical properties. Various hierarchical structures and functional nanocomposites based on CMGs have been prepared by self-assembly. Here, we review the recent advances in the assembly of CMGs in solution or at interfaces, and demonstrate the wide application of the resulting materials.
Co-reporter:Hua Bai, Kaixuan Sheng, Pengfei Zhang, Chun Li and Gaoquan Shi
Journal of Materials Chemistry A 2011 vol. 21(Issue 46) pp:18653-18658
Publication Date(Web):25 Oct 2011
DOI:10.1039/C1JM13918E
Graphene oxide/conducting polymer (GO/CP) composite hydrogels were prepared by in situ chemical polymerization of corresponding aromatic monomers in aqueous dispersions of GO sheets. GO/polypyrrole (PPy), GO/poly(3,4-ethylenedioxythiophene) (PEDOT) and GO/polyaniline (PANi) hydrogels were obtained by this technique, and the mechanism of gelation was discussed. Among them, GO/PPy composite hydrogels were tested to have low critical hydrogel concentrations (<1%, by weight), high storage moduli (>10 kPa) and electrical conductivity, and strong electrochemical activity. A gas sensor based on a typical GO/PPy hydrogel showed high sensitivity towards ammonia gas.
Co-reporter:Yang Zhao, Hua Bai, Yue Hu, Yan Li, Liangti Qu, Shaowen Zhang and Gaoquan Shi
Journal of Materials Chemistry A 2011 vol. 21(Issue 36) pp:13978-13983
Publication Date(Web):2011/08/08
DOI:10.1039/C1JM12014J
Two-dimensional polyaniline (PANI) nanosheets have been prepared inductively by electropolymerization of aniline monomer in an aqueous electrolyte containing sulfonated PANI-functionalized graphenes (SPANI-Gs). The SPANI-G aqueous solution is used directly as the electrolyte for electropolymerization of aniline. The formation of PANI nanosheets depends strongly on the aniline monomer concentration and the as-prepared nanosheets have a thickness of ca. 10 nm. Morphologic characterization reveals the resultant samples are stacked loosely on the surface of electrodes with a large surface area accessible to electrolyte. Electrochemical investigation has shown that the PANI nanosheets formed in the presence of SPANI-Gs had a large specific capacitance of 372 F g−1 at a current density of 0.3 A g−1, five times higher than that of a normal PANI film synthesized in the absence of SPANI-Gs, showing the great potential for energy storage applications.
Co-reporter:Yiqing Sun, Qiong Wu, Yuxi Xu, Hua Bai, Chun Li and Gaoquan Shi
Journal of Materials Chemistry A 2011 vol. 21(Issue 20) pp:7154-7160
Publication Date(Web):04 Apr 2011
DOI:10.1039/C0JM04434B
Flexible mesoporous graphitic films with high conductivities were prepared by graphitizing the composite films of graphene oxide (GO) and nanodiamond (ND). After graphitization, ND was changed into onion-like carbon (OC) and GO was reduced to conductive graphene. In the graphitic films, OC nanoparticles were sandwiched between thermally reduced graphene oxide (or graphene) sheets, which not only prevented the aggregation of graphene sheets, but also formed mesopores. The maximum specific surface area of the porous graphitic films was measured to be around 420 m2 g−1 and the diameters of their pores were mostly in the range of 2–11 nm. Furthermore, they are highly conductive with conductivities in the range of 7400 to 20300 S m−1. These films are flexible and can be mechanically shaped into the desired structures. Thus, they can be directly used as the electrodes of supercapacitors without the addition of a polymer binder or a conductive additive. The supercapacitors showed a long cycling life and their specific capacitance was optimized to be 143 F g−1 at a discharge rate of 0.2 A g−1.
Co-reporter:Zhiyi Yao, Hua Bai, Chun Li and Gaoquan Shi
Chemical Communications 2011 vol. 47(Issue 26) pp:7431-7433
Publication Date(Web):17 May 2011
DOI:10.1039/C1CC11990G
Colorimetric and fluorescent dual detection of cysteine (Cys) and homocysteine (Hcy) has been realized based on the ionic self-assembly of a cationic polythiophene derivative with aromatic derivatives of Cys and Hcy formed in situ.
Co-reporter:Cancan Huang, Hua Bai, Chun Li and Gaoquan Shi
Chemical Communications 2011 vol. 47(Issue 17) pp:4962-4964
Publication Date(Web):22 Mar 2011
DOI:10.1039/C1CC10412H
A graphene oxide/hemoglobin (GO/Hb) composite hydrogel was prepared for catalyzing a peroxidatic reaction in organic solvents with high yields, exceptional activity and stability.
Co-reporter:Chun Li, Gaoquan Shi
Electrochimica Acta 2011 Volume 56(Issue 28) pp:10737-10743
Publication Date(Web):1 December 2011
DOI:10.1016/j.electacta.2010.12.081
Conducting polymers (CPs) have been widely applied for fabricating various electrochemical devices such as sensors, actuators, solar cells, etc. To extend the functions or improving the performances of the devices, CPs frequently have to be blended with other functional materials to form composites. Graphene, a one-atom layer of graphite with unique two-dimensional structure and excellent mechanical and electrical properties, has become an increasing star in material science. Chemically converted graphene (CCG) prepared by reducing graphene oxide has satisfied processing property and complementary properties with CPs. Therefore, CCG is an important functional component for preparing high-performance CP-based composites. In this critical review, we mainly summarize the recent advancements in our group on the synthesis of CP/CCG composites and their electrochemical applications including supercapacitors, solar cells and electroanalysis.
Co-reporter:Yiqing Sun, Qiong Wu and Gaoquan Shi
Physical Chemistry Chemical Physics 2011 vol. 13(Issue 38) pp:17249-17254
Publication Date(Web):30 Aug 2011
DOI:10.1039/C1CP22409C
Self-assembled graphene organogel (SGO) with 3-dimensional (3D) macrostructure was prepared by solvothermal reduction of a graphene oxide (GO) dispersion in propylene carbonate (PC). This SGO was used as an electrode material for fabricating supercapacitors with a PC electrolyte. The supercapacitor can be operated in a wide voltage range of 0–3 V and exhibits a high specific capacitance of 140 F g−1 at a discharge current density of 1 A g−1. Furthermore, it can still keep a specific capacitance of 90 F g−1 at a high current density of 30 A g−1. The maximum energy density of the SGO based supercapacitor was tested to be 43.5 Wh kg−1, and this value is higher than those of the graphene based supercapacitors with aqueous or PC electrolytes reported previously. Furthermore, at a high discharge current density of 30 A g−1, the energy and power densities of the supercapacitor were measured to be 15.4 Wh kg−1 and 16300 W kg−1, respectively. These results indicate that the supercapacitor has a high specific capacitance and power density, and excellent rate capability.
Co-reporter:Qiong Wu, Yiqing Sun, Hua Bai and Gaoquan Shi
Physical Chemistry Chemical Physics 2011 vol. 13(Issue 23) pp:11193-11198
Publication Date(Web):11 May 2011
DOI:10.1039/C1CP20980A
2-Aminoanthraquinone (AAQ) molecules were covalently grafted onto chemically modified graphene (CMG), and the AAQ functionalized CMG sheets were self-assembled into macroporous hydrogels for supercapacitor electrodes. The electrode based on the AAQ modified self-assembled graphene hydrogel (AQSGH) showed a high specific capacitance of 258 F g−1 at a discharge current density of 0.3 A g−1, which is much larger than that of a pure graphene hydrogel (193 F g−1). Furthermore, the AQSGH electrode exhibited excellent rate capability and a long cycle life. This is mainly due to the covalently bonded AAQ moieties contributing additional redox capacitance. Furthermore, the highly conductive graphene hydrogel scaffold provided a large specific surface area for forming electric double layers and convenient routes for charge transfer and electrolyte diffusion.
Co-reporter:Kai-xuan SHENG, Yu-xi XU, Chun LI, Gao-quan SHI
New Carbon Materials 2011 Volume 26(Issue 1) pp:9-15
Publication Date(Web):January 2011
DOI:10.1016/S1872-5805(11)60062-0
Three-dimensional self-assembled graphene hydrogels (SGHs) have been fabricated by chemical reduction of graphene oxide (GO) with sodium ascorbate. The SGHs were characterized by scanning electron microscopy, rheological tests, electrical conductivity measurements, X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy. Results indicate that the reduction of GO promotes the assembly of graphene sheets. The SGHs are electrically conductive (1 S·m−1) and mechanically strong and exhibit excellent electrochemical performance. In 1 mol·L−1 aqueous solution of H2SO4, the specific capacitance of SGHs was measured to be about 240 F·g−1 at a discharge current density of 1.2 A·g−1.
Co-reporter:Kaixuan Sheng, Hua Bai, Yiqing Sun, Chun Li, Gaoquan Shi
Polymer 2011 Volume 52(Issue 24) pp:5567-5572
Publication Date(Web):10 November 2011
DOI:10.1016/j.polymer.2011.10.001
Graphene/polyaniline (PANI) multilayer films were prepared via alternate deposition of negatively charged graphene oxide (GO) and positively charged PANI upon electrostatic interaction, followed by the reduction of their GO components with hydroiodic acid. The thickness of the multilayer film increased linearly with the number of its bilayers and that of each bilayer was measured to be about 3 nm. Cyclic voltammetry studies indicated that these thin composite films were electroactive, and their redox reactions were related to the insertion-extraction of counter ions in PANI layers. Furthermore, the composite films were tested to be promising electrode materials for electrochromic devices even without using the conventional indium tin oxide (ITO) electrodes.Highlights► Multilayer films of graphene and polyaniline were prepared by layer-by-layer assembly. ► The multilayer films are conductive, electroactive and transparent. ► The multilayer films are promising electrode materials for electrochromic devices.
Co-reporter:Hua Bai ; Chun Li ; Xiaolin Wang
The Journal of Physical Chemistry C 2011 Volume 115(Issue 13) pp:5545-5551
Publication Date(Web):March 14, 2011
DOI:10.1021/jp1120299
Graphene oxide (GO) has been recognized as a unique two-dimensional building block for various graphene-based supramolecular architectures. In this article, we systematically studied the three-dimensional self-assembly of GO sheets in aqueous media to form hydrogels. The gelation of GO can be promoted by different supramolecular interactions, including hydrogen bonding, π-stacking, electrostatic interaction, and coordination. Furthermore, the lateral dimensions of GO sheets also have strong influences on GO gelation. The resulting GO hydrogels exhibited low critical gelation concentrations and good reversibility upon chemical stimulations. These findings indicate that GO has rich supramolecular properties, and its hydrogels may have a variety of technological applications.
Co-reporter:Li Zhang
The Journal of Physical Chemistry C 2011 Volume 115(Issue 34) pp:17206-17212
Publication Date(Web):July 27, 2011
DOI:10.1021/jp204036a
Graphene hydrogels prepared via hydrothermal reduction of graphene oxide dispersions (GH-Hs) were further reduced with hydrazine (Hz) or hydroiodic acid (HI) to improve their conductivities. The chemically reduced graphene hydrogels possess high conductivities of 1.3–3.2 S m–1, which are 1 order of magnitude higher than that of a GH-H (0.3 S m–1). The supercapacitor based on the Hz-reduced GH-H exhibited a high specific capacitance of 220 F g–1 at 1 A g–1, and this capacitance can be maintained for 74% as the discharging current density was increased up to 100 A g–1. Furthermore, it showed high power density and long cycle life. The high-performances of this supercapacitor make it promising for high rate charge/discharge applications.
Co-reporter:Xiluan Wang, Hua Bai, Zhiyi Yao, Anran Liu and Gaoquan Shi
Journal of Materials Chemistry A 2010 vol. 20(Issue 41) pp:9032-9036
Publication Date(Web):09 Sep 2010
DOI:10.1039/C0JM01852J
Composite films of chitosan and reduced graphene oxide (RGO) sheets with nacre-like layered structure have been prepared by vacuum filtration of the stable aqueous mixture of both components. The film containing 6 wt% RGO is electrically conductive with a conductivity of 1.2 S m−1. Furthermore, it is mechanically strong and ductile; its Young's modulus, tensile strength and elongation at break were measured to be 6.3 ± 0.2 GPa, 206 ± 6 MPa and 6.5 ± 0.6%, respectively. These values partly exceed those of nacre. The high mechanical and electrical properties of chitosan/RGO composite films are mainly attributed to the uniform dispersion of RGO nanofillers in the polymer matrices to form a compact layered structure.
Co-reporter:Yuanwei Gao, Hua Bai and Gaoquan Shi
Journal of Materials Chemistry A 2010 vol. 20(Issue 15) pp:2993-2998
Publication Date(Web):22 Feb 2010
DOI:10.1039/B924992C
A highly fluorescent conjugated oligomer, oligo(1-methoxyl pyrene) (OMOPr), was synthesized via electrochemical polymerization and its structure was studied by UV-vis spectroscopy, MALDI-TOF mass spectroscopy and ab initio calculation. The organic solutions of OMOPr emit strong blue lights and show solvatochromic effect, while these fluorescence emissions are quenched upon chain aggregation in its dry films. On the basis of these phenomena, a turn-on fluorescence sensor was fabricated and it can be used for detecting volatile aromatic compounds (VACs).
Co-reporter:Zhiyi Yao, Yugang Li, Chun Li and Gaoquan Shi
Chemical Communications 2010 vol. 46(Issue 45) pp:8639-8641
Publication Date(Web):13 Oct 2010
DOI:10.1039/C0CC02678F
A colorimetric strategy based on conjugated polyelectrolyte aggregates has been applied to determine and distinguish anionic, cationic and non-ionic surfactants.
Co-reporter:Zhiyi Yao, Hua Bai, Chun Li and Gaoquan Shi
Chemical Communications 2010 vol. 46(Issue 28) pp:5094-5096
Publication Date(Web):16 Jun 2010
DOI:10.1039/C002188A
The vital role of the charged moieties of monovalent aromatic anions in regulating the aggregation of a cationic conjugated polyelectrolyte was exploited in terms of the hard–soft acid–base principle and its application to colorimetric sensing of taurine was examined.
Co-reporter:Yiqing Sun, Chun Li, Yuxi Xu, Hua Bai, Zhiyi Yao and Gaoquan Shi
Chemical Communications 2010 vol. 46(Issue 26) pp:4740-4742
Publication Date(Web):26 May 2010
DOI:10.1039/C001635G
Graphitic carbon nitride, a polymeric catalyst, was immobilized on the surfaces of chemically converted graphene sheets to form a layered composite, which exhibited greatly improved conductivity and electrocatalytic performance on oxygen reduction reaction.
Co-reporter:Hua Bai, Chun Li, Xiaolin Wang and Gaoquan Shi
Chemical Communications 2010 vol. 46(Issue 14) pp:2376-2378
Publication Date(Web):05 Mar 2010
DOI:10.1039/C000051E
Graphene oxide/poly(vinyl alcohol) (GO/PVA) composite hydrogel was prepared and utilized for selective drug release at physiological pH.
Co-reporter:Kaixuan Sheng, Gaoquan Shi
Synthetic Metals 2010 Volume 160(11–12) pp:1354-1358
Publication Date(Web):June 2010
DOI:10.1016/j.synthmet.2010.03.023
Poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles with discus-like morphology were synthesized by chemical oxidation polymerization using bicelles as a soft template. The bicelles were assembled from the surfactant molecules of sodium perfluorooctanoate (FC7) and cetyltrimethylammonium bromide (CTAB). The PEDOT nanodiscuses have an average diameter around 200 nm and a central thickness of about 50 nm. The effects of synthetic parameters, such as surfactant concentration, molar ratio of oxidant and monomer, reaction temperature on PEDOT nanostructures have been investigated.
Co-reporter:Yuxi Xu, Kaixuan Sheng, Chun Li and Gaoquan Shi
ACS Nano 2010 Volume 4(Issue 7) pp:4324-4330
Publication Date(Web):June 30, 2010
DOI:10.1021/nn101187z
Self-assembly of two-dimensional graphene sheets is an important strategy for producing macroscopic graphene architectures for practical applications, such as thin films and layered paperlike materials. However, construction of graphene self-assembled macrostructures with three-dimensional networks has never been realized. In this paper, we prepared a self-assembled graphene hydrogel (SGH) via a convenient one-step hydrothermal method. The SGH is electrically conductive, mechanically strong, and thermally stable and exhibits a high specific capacitance. The high-performance SGH with inherent biocompatibility of carbon materials is attractive in the fields of biotechnology and electrochemistry, such as drug-delivery, tissue scaffolds, bionic nanocomposites, and supercapacitors.Keywords: graphene; hydrogel; hydrothermal reduction; self-assembly; three-dimensional;
Co-reporter:Xuejun Xie, Liangti Qu, Ce Zhou, Yan Li, Jia Zhu, Hua Bai, Gaoquan Shi, and Liming Dai
ACS Nano 2010 Volume 4(Issue 10) pp:6050
Publication Date(Web):September 9, 2010
DOI:10.1021/nn101563x
It is critically important to develop actuator systems for diverse needs ranging from robots and sensors to memory chips. The advancement of mechanical actuators depends on the development of new materials and rational structure design. In this study, we have developed a novel graphene electrochemical actuator based on a rationally designed monolithic graphene film with asymmetrically modified surfaces. Hexane and O2 plasma treatment were applied to the opposite sides of graphene film to induce the asymmetrical surface properties and hence asymmetrical electrochemical responses, responsible for actuation behaviors. The newly designed graphene actuator demonstrated here opens a new way for actuator fabrication and shows the potential of graphene film for applications in various electromechanical systems.Keywords: actuator; asymmetrical modification; electrochemistry; graphene
Co-reporter:Yuxi Xu, Qiong Wu, Yiqing Sun, Hua Bai, and Gaoquan Shi
ACS Nano 2010 Volume 4(Issue 12) pp:7358
Publication Date(Web):November 16, 2010
DOI:10.1021/nn1027104
Graphene and its functionalized derivatives are unique and versatile building blocks for self-assembly to fabricate graphene-based functional materials with hierarchical microstructures. Here we report a strategy for three-dimensional self-assembly of graphene oxide sheets and DNA to form multifunctional hydrogels. The hydrogels possess high mechanical strength, environmental stability, and dye-loading capacity, and a exhibit self-healing property. This study provides a new insight for the assembly of functionalized graphene with other building blocks, especially biomolecules, which will help rational design and preparation of hierarchical graphene-based materials.Keywords: DNA; graphene oxide; hydrogel; multifunctional; three-dimensional self-assembly
Co-reporter:Anran Liu ; Chun Li ; Hua Bai
The Journal of Physical Chemistry C 2010 Volume 114(Issue 51) pp:22783-22789
Publication Date(Web):November 19, 2010
DOI:10.1021/jp108826e
Composite films of sulfonated graphene (SG) and polypyrrole (PPy) were electrochemically deposited from the aqueous solutions containing pyrrole monomer, SG sheets, and dodecylbenzene sulfonic acid (DBSA). During the process of electrochemical polymerization, negatively charged SG sheets acted as a dopant of PPy. Thus, they were uniformly dispersed in the PPy matrices of resulting composites. The introduction of SG sheets improved the conductivity and electrochemical properties of PPy films. The composite films containing about 40% (by weight) SG showed a high specific capacitance of 285 F g−1 at a discharge rate of 0.5 A g−1. They also exhibited greatly improved electrochemical stability and rate performances.
Co-reporter:Wenjing Hong, Hua Bai, Yuxi Xu, Zhiyi Yao, Zhongze Gu and Gaoquan Shi
The Journal of Physical Chemistry C 2010 Volume 114(Issue 4) pp:1822-1826
Publication Date(Web):January 8, 2010
DOI:10.1021/jp9101724
Positively charged gold nanoparticles (GNPs) with diameters of 2−6 nm were self-assembled onto the surfaces of 1-pyrene butyric acid functionalized graphene (PFG) sheets simply by mixing their aqueous dispersions. The amount of GNPs assembled on PFG sheets can be easily modulated by controlling the feeding weight ratio of both components. Furthermore, it was found that PFG sheets had a high loading capability of GNPs, and the maximum value was determined to be about 300 times the PFG’s own weight. Glassy carbon (GC) electrodes modified with the composite of GNPs and PFG (GNP−PFG composite) showed strong electrocatalytic activity and high electrochemical stability. A uric acid electrochemical sensor based on the composite modified electrode exhibited rapid response and high sensitivity.
Co-reporter:Lu Zhao, Lei Tong, Chun Li, Zhongze Gu and Gaoquan Shi
Journal of Materials Chemistry A 2009 vol. 19(Issue 11) pp:1653-1658
Publication Date(Web):04 Feb 2009
DOI:10.1039/B819831D
Polypyrrole (PPy) films with inverse opal structures were synthesized by electrochemical polymerization of pyrrole using colloidal crystals as the template. The actuators based on these films exhibited higher actuation rates than those of the actuators made from flat PPy films at a given actuation potential. The nanosized caves of the inverse opal can trap particles with diameters smaller than their orifices, whereas the particles with diameters larger than those of cave orifices only can be adhered on the surfaces of actuators. The particles can be seized and released through electrochemical actuation. Furthermore, the particles with diameters smaller or larger than those of cave orifices can be separated from their mixtures.
Co-reporter:Zhiyi Yao, Xueling Feng, Chun Li and Gaoquan Shi
Chemical Communications 2009 (Issue 39) pp:5886-5888
Publication Date(Web):18 Aug 2009
DOI:10.1039/B912811E
A sensitive colorimetric and fluorescent probe based on a water-soluble cationic conjugated polyelectrolyte was applied to detect glutathione through an in situ premodification technique.
Co-reporter:Zhiyi Yao, Xueling Feng, Wenjing Hong, Chun Li and Gaoquan Shi
Chemical Communications 2009 (Issue 31) pp:4696-4698
Publication Date(Web):06 Jul 2009
DOI:10.1039/B904975D
A sensor based on an array of wavelengths of a cationic poythiophene derivative was applied to discriminate fifteen nucleotides along with monophosphate and pyrophosphate with 100% confidence limits.
Co-reporter:Hua Bai, Yuxi Xu, Lu Zhao, Chun Li and Gaoquan Shi
Chemical Communications 2009 (Issue 13) pp:1667-1669
Publication Date(Web):10 Feb 2009
DOI:10.1039/B821805F
Graphene sheets were stably dispersed in water by functionalization with sulfonated polyaniline (SPANI), and the composite film of SPANI-functionalized graphene showed improved electrochemical stability and enhanced electrocatalytic activity.
Co-reporter:Anran Liu, Lu Zhao, Hua Bai, Hongxin Zhao, Xinhui Xing and Gaoquan Shi
ACS Applied Materials & Interfaces 2009 Volume 1(Issue 4) pp:951
Publication Date(Web):April 8, 2009
DOI:10.1021/am9000387
A gold/polypyrrole (Au/PPy) bilayer actuator was fabricated by electrochemical deposition, and its surface was modified with a bioadhesive polymer, polydopamine. The actuator exhibited high performances of actuation in physiological media. Furthermore, the surface of the actuator is sticky in water and thus can seize bacteria from their aqueous solutions. Actuation greatly increased the efficiency of adhering bacteria on the actuator surface, and this technique provides a cheap and convenient approach for accumulating bacteria from physiological media.Keywords: bacteria seizing; bilayer actuator; bioadhesive surface; polydopamine; polypyrrole
Co-reporter:Yuxi Xu, Wenjing Hong, Hua Bai, Chun Li, Gaoquan Shi
Carbon 2009 Volume 47(Issue 15) pp:3538-3543
Publication Date(Web):December 2009
DOI:10.1016/j.carbon.2009.08.022
We report the preparation of mechanically strong and ductile poly(vinyl alcohol)/graphene oxide (GO) composite films with a layered structure simply by vacuum filtration. The Young’s modulus and tensile yield strength of the composite film containing 3 wt.% GO were measured to be 4.8 GPa and 110 ± 7 MPa, respectively. Furthermore, it is flexible and exhibits a large elongation at break (36 ± 4%). The high mechanical properties of the composite films are mainly due to the homogeneous dispersion and alignment of GO sheets in the polymer matrix and strong interfacial interactions between both components.
Co-reporter:Youqiang Chen, Hua Bai, Wenjing Hong and Gaoquan Shi
Analyst 2009 vol. 134(Issue 10) pp:2081-2086
Publication Date(Web):24 Aug 2009
DOI:10.1039/B910603K
A water-soluble complex of a cationic oligopyrene derivative, oligo(N1,N1,N1,N4,N4,N4-hexamethyl-2-(4-(pyren-1-yl) butanoyloxy) butane-1,4-diaminium bromide), and oligothymine has been prepared. The fluorescence sensor based on this complex showed high sensitivity and selectivity toward mercury(II) ions in aqueous media. The transduction mechanism of this sensor is based on the fluorescence self-quenching of oligopyrene in watervia the interchain π-stacking arising from the specific thymine–Hg–thymine complexation. The detection limit of this sensor was measured to be as low as 5 × 10−9 mol L−1. In addition, the fluorescent color change of the complex solution allows naked-eye detection of mercury(II) ions with an extremely low detection limit of 5 × 10−6 mol L−1.
Co-reporter:Glen Murray Chapman, Hua Bai, Chun Li, Gaoquan Shi
Materials Chemistry and Physics 2009 Volume 114(Issue 1) pp:120-124
Publication Date(Web):15 March 2009
DOI:10.1016/j.matchemphys.2008.08.062
Silver nanoparticles have been grown by electrolysis of a silver ammonia solution in the presence of a small amount of aluminium nitrate. The Ag particles were found to exist in several shapes ranging from spherical, rod and sheet-like depending upon the conditions used for electrosynthesis. Films composed of these nanoparticles have micro-nanoscale binary structures. After passivation with n-dodecanethiol, these surfaces showed super-hydrophobic property with contact angles around 150° and sliding angles less than 5°.
Co-reporter:XueLing Feng;ZhiYi Yao;Chun Li
Science Bulletin 2009 Volume 54( Issue 14) pp:2451-2456
Publication Date(Web):2009 July
DOI:10.1007/s11434-009-0427-5
Insulated molecular wires of poly(phenylenevinylene) (PPV) were prepared by wrapping the conjugated backbones with dendrons through a noncovalent approach. It was found that electrostatic interaction between the quaternary ammonium groups of PPV-1 and the carboxylate moieties in dendrons induced the packing of dendrons along PPV-1 conjugated backbones. Absorption and emission spectroscopic examinations in solution and solid film indicated that the PPV-1 backbones adopted a more planar and isolated conformation in the complexes. Furthermore, interchain interactions in the complexes could be greatly reduced, improving the quantum yield of PPV-1.
Co-reporter:Lei Tong, Chun Li, Feng’en Chen, Hua Bai, Lu Zhao and Gaoquan Shi
The Journal of Physical Chemistry C 2009 Volume 113(Issue 17) pp:7411-7415
Publication Date(Web):2017-2-22
DOI:10.1021/jp811458h
We report a flexible photodetector with a sandwich structure of Au/polythiophene (PTh)/Au, which consists of two Au electrodes with a thickness of 30 nm each and a PTh layer with a thickness of 10−40 μm. The devices showed strong and fast photoresponses under excitation through the gold electrodes using white light or a 514 nm laser beam. Upon illumination with a 40 mW/cm2 514 nm laser beam and under a low bias electric field of 0.2 V/μm, the device with a 20 μm thick PTh layer exhibited an external quantum efficiency up to 136%. These devices are flexible and can be bent to large angles and fabricated into large sizes with arbitrary shapes.
Co-reporter:Hua Bai, Lu Zhao, Canhui Lu, Chun Li, Gaoquan Shi
Polymer 2009 50(14) pp: 3292-3301
Publication Date(Web):
DOI:10.1016/j.polymer.2009.04.066
Co-reporter:Youqiang Chen, Hua Bai, Qi Chen, Chun Li, Gaoquan Shi
Sensors and Actuators B: Chemical 2009 Volume 138(Issue 2) pp:563-571
Publication Date(Web):6 May 2009
DOI:10.1016/j.snb.2009.02.047
A water-soluble cationic conjugated oligomer, oligo(2-(4-(1-pyrenyl)butanoyloxy)ethyltrimethylammonium bromide) (OPBEAB) was synthesized by the combination of chemical and electrochemical synthesis techniques. The oligomer has an average repeat unit of 4 and a high quantum yield (Ф) of 0.7 in an aqueous solution containing 5.91 × 10−3 mol L−1 sodium dodecyl sulfate (SDS). In this medium, surfactant molecules formed shielding layers along the OPBEAB chains and prevented aggregation of the oligomer and also improved its fluorescence stability. The fluorescence quenching of cationic oligomer (OPBEAB) depends strongly on the mixing sequence of the probe molecule (OPBEAB), analyte (TNT), and anionic surfactant (SDS). A molecule probe based on OPBEAB can rapidly detect ultra-trace TNT in both pure aqueous solution and environmental ground water with high sensitivity. The Stern–Volmer constant (KSV) of the probe in aqueous solution was measured to be as high as 5.30 × 105 mol−1 L and the limit of detection was about 7.0 × 10−8 mol L−1 (70 ppb) under optimized conditions.
Co-reporter:Zhiyi Yao, Chun Li and Gaoquan Shi
Langmuir 2008 Volume 24(Issue 22) pp:12829-12835
Publication Date(Web):October 23, 2008
DOI:10.1021/la802086d
Optically active supramolecular complexes of water-soluble achiral polythiophene (PT) derivatives, PMTPA or PMTEA (Chart 1), and folic acid have been prepared; and the complex formation processes have been studied by absorption, emission, and circular dichroism (CD) spectroscopies. The complexes exhibited unique split-type induced CDs in the π−π* transition region of PTs, indicating that the molecular chirality of the glutamic acid moiety in folic acid was expressed in PT backbones. The influences of temperature, solvent composition, and the structures of the inducing molecules on the chirality induction to PTs were also investigated, and a possible mechanism for the formation of chiral superstructures was proposed. Furthermore, it was found that, upon addition of folic acid into aqueous solution of PTs (PMTPA or PMTEA), a dramatic color change from yellow to purple along with the emission quenching of PT derivatives was observed. PMTEA, having one fewer carbon in the hydrophobic side chain relative to PMTPA, showed better selectivity toward folic acid sensing over ATP because of its higher solubility in water and the appropriate hydrophilic/hydrophobic balance in the complex. Therefore, it can be applied as a colorimetric and fluorescent probe for detecting folic acid with high selectivity and sensitivity. Besides naked-eye detection of folic acid, the detection limit can be extended to be 10−8 M by using fluorometry and PMTEA as the probing molecule.
Co-reporter:Hua Bai;Chun Li
ChemPhysChem 2008 Volume 9( Issue 13) pp:1908-1913
Publication Date(Web):
DOI:10.1002/cphc.200800149
Abstract
An ester (PBPOSS) of 1-pyrenebutyric acid (PBA) and 1-(2,3-propanediol)propoxy-3,5,7,9,11,13,15-isobutylpentacyclo-[9.5.1.1(3,9).1(5,15).1(7,13)]octasiloxane (a polyhedral oligomeric silsesquioxane, POSS) is synthesized by simple one-step esterification. Thin films of PBPOSS fabricated by the spin-coating technique exhibit strong excimer emissions of visible light. Upon exposure to the vapours of nitroaromatic compounds, including trinitro- toluene and dinitrotoluene, the films show fast fluorescence quenching. The high performance of these gas sensors is due to the high excimer contents and good vapour permeability of the PBPOSS films. Spectroscopic studies indicate that the crystallization of the POSS moieties in PBPOSS films induce the formation of pyrenyl excimers.
Co-reporter:X. M. He;C. Li;F. E. Chen;G. Q. Shi
Advanced Functional Materials 2007 Volume 17(Issue 15) pp:
Publication Date(Web):23 AUG 2007
DOI:10.1002/adfm.200600869
Bilayer actuators consisting of a layer of aligned PPy microtubules with the length of 15 μm and a layer of compact PPy film with the thickness of 15 μm have been fabricated. The actuators can bend to an angle much larger than 90° at an actuation rate of ∼ 100° s–1 under a driving potential of 0.8 V versus Ag/AgCl. The microtubule layers of both type actuators are “sticky”, and can capture or trap polystyrene microparticles from their dilute dispersions. Moreover, the captured particles can be extensively released by sonication or partly released by electrochemically reducing the actuators in the aqueous electrolytes. On the basis of extensive investigations including controlling the conditions of electrochemical actuation and the redox states of PPy microtubules, adjusting the particle size and composition, possible mechanisms for capturing and releasing microparticles were proposed.
Co-reporter:Shibin Wang, Gaoquan Shi
Materials Chemistry and Physics 2007 Volume 102(2–3) pp:255-259
Publication Date(Web):15 April 2007
DOI:10.1016/j.matchemphys.2006.12.014
Uniformly sized silver/polypyrrole (Ag/PPy) core-shell nanoparticles were synthesized by one-step hydrothermal reaction of pyrrole and silver nitrate in the presence of polyvinyl pyrrolidone (PVP) as protection agent. The morphology and structures of the nanoparticles have been studied by scanning and transmission electronic microscopes, X-ray diffractometer and Raman spectroscopy. The experimental results indicated that the particles had 120 nm silver cores with 20 nm polypyrrole (PPy) coatings. The reaction conditions have strong effects on the morphology of the nanoparticles.
Co-reporter:Gaoyi Han
Journal of Applied Polymer Science 2007 Volume 103(Issue 3) pp:1490-1494
Publication Date(Web):8 NOV 2006
DOI:10.1002/app.25095
An organic salt (FeAOT) is synthesized by the reaction of sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT) and ferric chloride. It is fabricated into fibers by manual drawing and electrospinning. Long polypyrrole (PPy) fibers are obtained for the first time by a vapor deposition reaction of pyrrole on the FeAOT fibers, and this technique is extended to the synthesis of PPy composite fibers with multiwalled carbon nanotubes (PPy–MWCNT fibers). The PPy and PPy–MWCNT fibers have a nanoporous morphology, a conductivity of 10–15 S cm−1, and a tensile strength of 12–43 MPa. The electrochemistry and current–voltage characteristics of the PPy fibers are also studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1490–1494, 2007
Co-reporter:Qi Chen;Hua Bai
Science Bulletin 2007 Volume 52( Issue 15) pp:2017-2023
Publication Date(Web):2007 August
DOI:10.1007/s11434-007-0314-x
Organic/metallic composites have demonstrated electrical bistability, as well as memory effects. These advanced materials have shown potential applications in digital information storage because of their good stability, flexibility and fast response speed. The electric bistability phenomenon can be explained by electric field-induced electron transfer/storage. This article reviews the recent progress of memory devices based on organic/metallic and polymeric composites with electric bistability.
Co-reporter:Gaoyi Han, Gaoquan Shi
Thin Solid Films 2007 Volume 515(Issue 17) pp:6986-6991
Publication Date(Web):13 June 2007
DOI:10.1016/j.tsf.2007.02.007
Co-reporter:Zhuo Zhang, Hong Tang, Haifeng Wang, Xiao Liang, Jia Liu, Yong Qiu, Gaoquan Shi
Thin Solid Films 2007 Volume 515(7–8) pp:3893-3897
Publication Date(Web):26 February 2007
DOI:10.1016/j.tsf.2006.10.112
9,10-Bis-[4-(4-pentyl-cyclohexyl)-phenyl]-anthracene (BPCPA) was synthesized and characterized. Spectral results indicated that this compound is a strong blue light emitter with quantum yield of 1.0. BPCPA has also been applied as the light-emitting layer for fabrication of organic light-emitting diodes (OLEDs) by using a 4,7-diphenyl-1,10-phenanthroline film as the hole blocking/electron transporting layer and N, N′-biphenyl-N,N′-bis-(1-naphenyl)-[1,1′-biphenyl]-4,4′-diamine film as the hole transporting layer. The peak emission of electroluminescence of this OLED device is at about 440 nm and its Commission Internationale de l'Eclairage color coordinates are (0.15, 0.07) at potentials of 7 to 9 V. These values are very close to the standard of National Television Standards Committee for blue light (0.14, 0.08). Furthermore, BPCPA has high thermal stability with decomposition temperatures over 375 °C and melting point of 276.4 °C. BPCPA also shows a liquid crystal mesophase at 277 °C which indicates its potential applications in liquid crystal display.
Co-reporter:Xufeng Wu, Hua Bai, Chun Li, Gewu Lu and Gaoquan Shi
Chemical Communications 2006 (Issue 15) pp:1655-1657
Publication Date(Web):08 Mar 2006
DOI:10.1039/B516497D
Highly oriented ZnO nanoneedle/nanorods arrays have been fabricated by direct oxidation of zinc foil in alkaline zincate ion solution at near room temperature (20 °C for nanoneedles, 30 °C for nanorods).
Co-reporter:Yonghong He, Jinying Yuan, Gaoquan Shi, Peiyi Wu
Materials Chemistry and Physics 2006 Volume 99(2–3) pp:253-257
Publication Date(Web):10 October 2006
DOI:10.1016/j.matchemphys.2005.10.033
Gold nanoparticles (NPs)/polypyrrole (PPy) bi-layer film was fabricated through a solution-based seeding process. The growth of the gold layer has been studied by the use of a field emission scanning electron microscope and UV–vis spectroscope. The results demonstrated that the PPy chains served as the reductant of chloroauric acid and the ligands to stabilize gold NPs. The resulting gold/PPy bi-layer film has a high conductivity of approximately 300 S cm−1 and can be fabricated into actuators because of its anistropic structure.
Co-reporter:Yi He, Xufeng Wu, Gewu Lu, Gaoquan Shi
Materials Chemistry and Physics 2006 Volume 98(Issue 1) pp:178-182
Publication Date(Web):1 July 2006
DOI:10.1016/j.matchemphys.2005.09.008
Single crystal silver nanosheets have been synthesized in water without any organic surfactant or polymer to direct the growth of nanoparticles. The nanosheets were formed through a modified silver mirror reaction in which silver ammonia ions were reduced to metallic silver by glucose and an inorganic species, aluminum nitrate, was introduced to the system. Thermodynamic calculation demonstrates that the aluminum hydroxide generated in situ from aluminum nitrate plays a key role in the formation of silver nanosheets.
Co-reporter:Zhipan Zhang, Fan Wang, Feng'en Chen, Gaoquan Shi
Materials Letters 2006 Volume 60(Issue 8) pp:1039-1042
Publication Date(Web):April 2006
DOI:10.1016/j.matlet.2005.10.071
Gold core–polythiophene shell composite nanoparticles with a diameter of 6–8 nm have been prepared via a two-step process. The morphology and structures of the obtained nanocomposites were characterized by transmission electron microscopy, infrared and Raman spectroscopies. The nanoparticles can be stably dispersed in usual organic solvents such as ethanol. Thus, they can be easily processed and have potential applications in nanoscale buildings and development of novel electronic devices.
Co-reporter:Ximin He, Gaoquan Shi
Sensors and Actuators B: Chemical 2006 Volume 115(Issue 1) pp:488-493
Publication Date(Web):23 May 2006
DOI:10.1016/j.snb.2005.10.011
A polypyrrole (PPy) composite film with a pure PPy zone and a PPy–TiO2 nanoparticle composite zone in its cross-sectional direction was synthesized by direct oxidation of pyrrole successively in an electrolyte with or without TiO2 nanoparticles. The volume content of TiO2 in the composite film was tested to be lower than 0.9%. The actuator fabricated from this monolithic PPy film bends uniformly in two directions with a maximum bending angle larger than 90° and has a high response rate (∼115° s−1 at 1.0 V versus SCE) and a long lifetime (>20,000 cycles) in a 1 M LiClO4 aqueous solution. The high performance of this actuator resulted from the non-delamination and intrinsic asymmetric structure and the high conductivity of PPy film.
Co-reporter:Gaoyi Han, Gaoquan Shi
Sensors and Actuators B: Chemical 2006 Volume 113(Issue 1) pp:259-264
Publication Date(Web):17 January 2006
DOI:10.1016/j.snb.2005.02.055
Polypyrrole film with porous and compact zones in its vertical direction has been synthesized by direct oxidation of pyrrole in the mixed solvent of acetonitrile and dichloromethane contained a certain amount of anion surfactant of sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT). The actuator based on this single-layer film bends uniformly with the maximum bending angle much larger than 90° and has a fast response rate (∼60° s−1 at 1.0 V versus SCE) and a long lifetime (>20,000 cycles). The high performance of this actuator is mainly due to that the PPy film has a high conductivity and the actuator does not have delamination problem.
Co-reporter:Xufeng Wu and Gaoquan Shi
Journal of Materials Chemistry A 2005 vol. 15(Issue 18) pp:1833-1837
Publication Date(Web):04 Mar 2005
DOI:10.1039/B417446A
A carboxyl-containing conducting oligomer, poly(pyrenebutyric acid)
(PPBA), has been synthesized for non-covalent sidewall functionalization of single-walled carbon nanotubes (SWNTs) by direct oxidation of α-pyrenebutyric acid (PBA) in boron trifluoride diethyl etherate (BFEE) containing SWNTs. The initial feeding weight ratio of the monomer and SWNTs can strongly influence the thickness of the oligomer coating on SWNTs and also the diameter of the fibril nanocomposites. The pyrene moieties of PPBA interacted with the sidewalls of SWNTs because of their large aromatic rings, which meant that the composite could be stably dispersed in many common organic solvents and aqueous alkaline solutions. The structure and optical properties of PPBA and SWNT/PPBA composites have also been studied.
Co-reporter:Jiaxin Zhang;Chen Liu
Journal of Applied Polymer Science 2005 Volume 96(Issue 3) pp:732-739
Publication Date(Web):23 FEB 2005
DOI:10.1002/app.21520
Polyaniline (PANI) in three ground states—emeraldine base (EB), leucoemeraldine base (LEB), and pernigraniline base (PNB)—were studied by Raman spectroscopy in the temperature scale of −195 to about 375°C. The Raman spectral results demonstrated that a crosslinking reaction occurred on EB chains at high temperatures, whereas the phenyl torsion angles of EB chains decreased during the cooling process. LEB was unstable and was gradually converted to EB during the heating process, although its chain conformation remained stable by cooling. The spectral change tendency of PNB was similar to that of EB during the heating process. Although the torsion angle of PNB also decreased with decreasing temperature, like that of EB, this behavior was hard to observe experimentally because of the relatively “free ” rotation of its phenyl rings. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96:732–739, 2005
Co-reporter:Mingming Ma;Liangti Qu
Journal of Applied Polymer Science 2005 Volume 98(Issue 6) pp:2550-2554
Publication Date(Web):29 SEP 2005
DOI:10.1002/app.22455
Highly sensitive glucose oxidase (GOD) electrodes were fabricated on the basis of microstructured polypyrrole (PPy) films. The microstructures of the PPy films had a morphology like cups and were arranged in a density of approximately 4000 units/cm2. GOD was immobilized in microstructured PPy films coated on a Pt or stainless steel (SS; AISI 321) substrate electrode. The GOD/PPy/Pt electrode showed a linear response to glucose concentrations in the range of 0–17 mM at a potential of 0.4 V (vs a saturated calomel electrode). Its sensitivity was measured to be approximately 660 nA/(mM cm2) at 15°C, and the response time (t95%) was approximately 20 s. In comparison, the sensitivity of the GOD/PPy/Pt electrode based on a flat PPy film was only approximately 330 nA/(mM cm2) under the same conditions. The sensitivity of the microstructured GOD/PPy/Pt electrode could be increased to as high as approximately 2400 nA/(mM cm2) at 37°C. The microstructured GOD/PPy/SS electrode had a sensitivity of approximately 550 nA/(mM cm2) and a t95% value of approximately 30 s at 15°C and 0.4 V. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2550–2554, 2005
Co-reporter:Gaoyi Han, Jinying Yuan, Gaoquan Shi, Fei Wei
Thin Solid Films 2005 Volume 474(1–2) pp:64-69
Publication Date(Web):1 March 2005
DOI:10.1016/j.tsf.2004.08.011
The nanocomposite films of polypyrrole (PPy) and multiwalled carbon nanotubes (MWCNT) were electrochemically synthesized by direct oxidation of pyrrole in 0.1 M aqueous solution of dodecylbenzene sulfonic acid containing a certain amount of MWCNT. The morphology, electronic conductivity, and thermal stability of the composite films have been studied by scanning electron microscopy, Raman spectroscopy and thermal gravimetric analysis. It was found that the mixing sequence of the surfactant, the monomer and MWCNT strongly influenced the compositions and thermal stability of the composite films. Raman spectroscopic studies indicated that the contents of the oxidized species of PPy in the composite films decreased faster than that of the neutral species during the heating process. The conductivity of each composite film showed a maximum in the temperature scale of 120–180 °C and then decreased dramatically with the increase of temperature.
Co-reporter:L. Qu;G. Shi;X. Wu;B. Fan
Advanced Materials 2004 Volume 16(Issue 14) pp:
Publication Date(Web):2 AUG 2004
DOI:10.1002/adma.200400044
Many novel applications of silver become possible if silver nanotubes can be produced reliably and easily. A simple, template-assisted procedure is reported here. The Figure shows a scanning electron microscopy image of one of the silver nanotubes, which was broken by ultrasonic vibration, demonstrating that the nanostructure is indeed a hollow nanotube and showing that the nanotube is formed of (crystalline) nanoparticles.
Co-reporter:Jinying Yuan, Liangti Qu, Deqiang Zhang and Gaoquan Shi
Chemical Communications 2004 (Issue 8) pp:994-995
Publication Date(Web):18 Mar 2004
DOI:10.1039/B400614C
Linear arranged polypyrrole microcontainers have been assembled into one or two lines on patterned silicon micro-electrodes with line widths of 50 and 200 µm, respectively.
Co-reporter:Liangti Qu and Gaoquan Shi
Chemical Communications 2004 (Issue 24) pp:2800-2801
Publication Date(Web):03 Nov 2004
DOI:10.1039/B412638F
Highly crystalline oligopyrene nanowires have been prepared by template-assisted electropolymerization of pyrene in boron trifluoride diethyl etherate medium, which can emit strong blue, green or red fluorescence as excited at 405, 488 or 543 nm, respectively.
Co-reporter:Jiaxin Zhang;Chen Liu;Feng'en Chen
Journal of Applied Polymer Science 2004 Volume 92(Issue 1) pp:171-177
Publication Date(Web):27 JAN 2004
DOI:10.1002/app.13706
Polyaniline (PANI) films doped with hydrochloric acid have been electrochemically deposited on mirrorlike platinum electrode surfaces by a cyclic voltammogram method. The Raman spectra of doped PANI films were investigated by excitation with a 633- or 785-nm laser beam. It was found that the overall features of the Raman spectra depend strongly on the film thickness, due mainly to that the doping level of PANI film increases during the film-growth process. X-ray photoelectron spectroscopic (XPS) analysis and ultraviolet (UV)-visible absorption spectrum results also confirmed this finding. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 171–177, 2004
Co-reporter:Enhua Li;Xiaoyin Hong;Peiyi Wu
Journal of Applied Polymer Science 2004 Volume 93(Issue 1) pp:189-195
Publication Date(Web):12 APR 2004
DOI:10.1002/app.20448
Poly(methylphenylene) (PMeP) films were prepared by direct oxidation of toluene in the mixed electrolytes of boron trifluoride diethyl etherate (BFEE) and trifluoroacetic acid (TFA). The oxidation potential of toluene in pure BFEE was measured to be 1.52 V versus saturated calomel electrode (SCE). This value was much lower than that determined in a neutral medium such as acetonitrile (2.13 V versus SCE). The introduction of TFA into BFEE decreased the oxidation potential of toluene and also improved the properties of as-formed polymer films. Infrared and Raman spectra confirmed the formation of PMeP films. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 189–195, 2004
Co-reporter:GY Han;GQ Shi;LT Qu;JY Yuan;FE Chen;PY Wu
Polymer International 2004 Volume 53(Issue 10) pp:
Publication Date(Web):22 JUN 2004
DOI:10.1002/pi.1597
N-Substituted pyrrole derivatives with chiral side groups have been synthesized and electrochemically polymerized in acetonitrile containing tetrabutylammonium perchlorate (TBAClO4) and (S)-(+)-camphor-10-sulfonic acid ((S)-(+)-CSA) or (R)-(−)-camphor-10-sulfonic acid ((R)-(−)-CSA). The resulting N-substituted polypyrrole films were characterized by cyclic voltammetry, infrared, Raman and X-ray photoelectron (XPS) spectroscopies. XPS results demonstrated that the as-grown polymer films are preferably doped by CSA anions when the monomer and the CSA anion have the same optical rotation dispersion (ORD). Furthermore, the conductivities of the polymers synthesized in the media containing CSA with the same ORD of the corresponding monomers were measured to be about 2–10 times higher than those of polymers obtained from electrolytes without CSA. Copyright © 2004 Society of Chemical Industry
Co-reporter:Zhimin Huang;Jiaxin Zhang;Enhua Li;Liangti Qu
Journal of Applied Polymer Science 2004 Volume 92(Issue 3) pp:1939-1944
Publication Date(Web):4 MAR 2004
DOI:10.1002/app.20190
β-Naphthalene sulfonic acid (β-NSA) has been electrochemically polymerized in a mixed electrolyte of boron trifluoride diethyl etherate (BFEE) solution mixed with a certain amount of trifluoroacetic acid (TFA) or concentrated sulfuric acid (SA). The poly(β-naphthalene sulfonic acid) (PNSA) film prepared from the medium of BFEE+TFA was partly soluble in methanol. On the other hand, the polymer obtained from the system of BFEE+SA was soluble in water and general polar organic solvents such as methanol, alcohol, and acetone. The structure of PNSA was examined by infrared and UV spectra. Fluorescent spectral studies indicate that the polymer is a blue light emitter with fluorescence quantum efficiency of ∼ 4%. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1939–1944, 2004
Co-reporter:Xufeng Wu;Feng'En Chen;Shaohu Han;Junbiao Peng
Journal of Polymer Science Part A: Polymer Chemistry 2004 Volume 42(Issue 12) pp:3049-3054
Publication Date(Web):12 MAY 2004
DOI:10.1002/pola.20171
Poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) with a molar mass of 26–47 × 104 g mol−1 and a polydispersity of 2.5–3.2 was synthesized by a liquid–solid two-phase reaction. The liquid phase was tetrahydrofuran (THF) containing 1,4-bis(chloromethyl)-2-methoxy-5-(2′-ethylhexyloxy)benzene as the monomer and a certain amount of tetrabutylammonium bromide as a phase-transfer catalyst. The solid phase consisted of potassium hydroxide particles with diameters smaller than 0.5 mm. The reaction was carried out at a low temperature of 0 °C and under nitrogen protection. No gelation was observed during the polymerization process, and the polymer was soluble in the usual organic solvents, such as chloroform, toluene, THF, and xylene. A polymer light-emitting diode was fabricated with MEH-PPV as an active luminescent layer. The device had an indium tin oxide/poly(3,4-ethylenedioxylthiophene) (PEDOT)/MEH-PPV/Ba/Al configuration. It showed a turn-on voltage of 3.3 V, a luminescence intensity at 6.1 V of 550 cd/m2, a luminescence efficiency of 0.43 cd/A, and a quantum efficiency of 0.57%. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3049–3054, 2004
Co-reporter:Liangti Qu and Gaoquan Shi
Chemical Communications 2003 (Issue 2) pp:206-207
Publication Date(Web):06 Dec 2002
DOI:10.1039/B209245J
Polypyrrole microstructures with unusual morphologies have been synthesized by direct electrochemical oxidation of pyrrole in β-naphthalenesulfonic acid aqueous solution.
Co-reporter:Zhimin Huang, Liangti Qu, Gaoquan Shi, Feng'en Chen, Xiaoyin Hong
Journal of Electroanalytical Chemistry 2003 Volume 556() pp:159-165
Publication Date(Web):30 September 2003
DOI:10.1016/S0022-0728(03)00341-3
Naphthalene has been polymerized electrochemically in the mixed electrolyte of boron trifluoride diethyl etherate (BFEE) and trifluoroacetic acid (TFA). The oxidation potential of the monomer in this medium was measured as approximately 1.0 V (vs. SCE), which was much lower than that detected in a neutral electrolyte such as acetonitrile (1.55 V vs. SCE). A powdery polymer with a conductivity of 2.6×10−3 S cm−1 was obtained. The addition of a small amount (∼5%, by weight) of polyethylene glycol with a molar mass of 400 g (PEG 400) into the mixed electrolyte can decrease the oxidation potential of the monomer further to approximately 0.7 V versus SCE. A free-standing polynaphthalene (PNA) film with a conductivity of 5.9×10−2 S cm−1 was obtained from this medium for the first time. The structure of the polymer has been investigated by UV–Vis, infrared and Raman spectroscopies.
Co-reporter:Zhiming Huang, Gaoquan Shi, Liangti Qu, Xiaoyin Hong
Journal of Electroanalytical Chemistry 2003 Volume 544() pp:41-46
Publication Date(Web):13 March 2003
DOI:10.1016/S0022-0728(03)00063-9
β-Naphthalene sulfonic acid (β-NSA) has been electrochemically polymerized in a mixed electrolyte of boron trifluoride diethyl etherate (BFEE) solution and trifluoroacetic acid (TFA). As-grown poly(β-naphthalene sulfonic acid) (PNSA) is partly soluble in methanol and has a conductivity of 0.95 S cm−1. Its structure has been examined by infrared, H1-NMR and UV spectra. Fluorescent spectral studies indicate that the polymer is a blue light emitter with a fluorescence quantum efficiency of 4%.
Co-reporter:Mingming Ma;Chanjuan Xi
Journal of Applied Polymer Science 2003 Volume 89(Issue 1) pp:16-23
Publication Date(Web):21 APR 2003
DOI:10.1002/app.12084
A novel liquid/solid two-phase reaction of α,α,α-trichlorotoluene (PhCCl3) and acetonitrile (AN) has been discovered that produces a carbon-based polymer with diamondlike structure at the atomic level. The solid phase is potassium hydroxide particles, and the liquid phase is a tetrahydrofuran solution of PhCCl3 and AN containing a certain amount of tetrabutylammonium bromide as a phase-transfer catalyst. The structure of the carbon-based polymer has been characterized by elemental analysis, Fourier transform infrared spectroscopy, and 1H- and 13C-NMR spectroscopy. The pyrolysis of the carbon-based polymer at 800°C under a nitrogen atmosphere leads to the formation of a diamondlike carbonaceous material according to the results of X-ray photoelectron spectroscopy and Raman spectroscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 16–23, 2003
Co-reporter:Fengén Chen;Jiaxin Zhang;Fan Wang
Journal of Applied Polymer Science 2003 Volume 89(Issue 12) pp:3390-3395
Publication Date(Web):1 JUL 2003
DOI:10.1002/app.12606
Polypyrrole films were electrochemically synthesized by direct oxidative polymerization of pyrrole in acetonitrile containing β-naphthalene sulfonic acid or tetrabutylammonium tetrafluoroborate as an supporting electrolyte. We characterized the as-grown polypyrrole films by resonance Raman spectroscopy in the temperature region of −195 to 275°C. During the heating process, the Raman bands related to the oxidized species decreased gradually, due mainly to the affect of oxygen and moisture in the air, and, finally, the neutral polymer chains decomposed into disordered carbons. During the cooling process, polymer chains changed from disordered (coil-like) to ordered (rodlike) structures and caused the elongation of the conjugated chain length. This results in a red shift of the absorption of the electron spectra of the polymer and the enhancements of the Raman bands related to the oxidized species. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3390–3395, 2003
Co-reporter:Chen Liu;Jiaxin Zhang;Feng'En Chen;Liangti Qu
Journal of Applied Polymer Science 2003 Volume 90(Issue 5) pp:1267-1272
Publication Date(Web):27 AUG 2003
DOI:10.1002/app.12745
A novel proton-gel-conducting polymer electrolyte was prepared by blending boron trifluoride diethyl etherate with poly(ethylene oxide) (PEO), glycerol, and propylene carbonate (PC) at certain molar ratios. The electrolytes exhibited ambient conductivity from 10−5 to 10−3 S/cm. DSC results indicated that the electrolytes were amorphous. The 1H-NMR and Raman spectra showed strong interactions between the Lewis acid and the hydroxyl groups both of glycerol and of PEO. This resulted in the formation of protons for ionic conduction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1267–1272, 2003
Co-reporter:Feng’en Chen, Gaoquan Shi, Mingxiao Fu, Liangti Qu, Xiaoyin Hong
Synthetic Metals 2003 Volume 132(Issue 2) pp:125-132
Publication Date(Web):12 January 2003
DOI:10.1016/S0379-6779(02)00197-2
In this paper, we present resonance Raman spectroscopic studies on as-grown thin polypyrrole (PPy) films electrochemically deposited on flat platinum electrode surfaces by direct oxidation of pyrrole in acetonitrile. It was found that the overall features of the Raman spectra depend strongly on film thickness, mainly due to that the doping level of PPy increases during film growth process. Electrochemical and X-ray photoelectron spectroscopic (XPS) examinations have confirmed this discovery. The doping level of PPy film with a given thickness also depends on the property of supporting electrolyte.
Co-reporter:Gaoquan Shi;Fan Wang;Fengen Chen;Jingkun Xu;Jiaxin Zhang;Xiaoyin Hong
Journal of Applied Polymer Science 2003 Volume 87(Issue 3) pp:502-509
Publication Date(Web):13 NOV 2002
DOI:10.1002/app.11441
3-Chlorothiophene (CT) was electrochemically polymerized in mixed electrolytes of a boron trifluoride diethyl etherate solution containing 0–20% (by volume) sulfuric acid. The oxidation potentials of the monomer in these media were measured to be only 1.06–1.31 V (vs Ag/AgCl). These values were much lower than that of CT in acetonitrile and 0.1 mol/L (Bu)4NBF4 (1.92 V vs Ag/AgCl). Poly(3-chlorothiophene) (PCT) films with conductivities of 0.1–2 S cm−1 were obtained. The structure, morphology, and electrochemical behavior of the PCT films also were investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 502–509, 2003
Co-reporter:Feng'en Chen, Gaoquan Shi, Jiaxing Zhang, Mingxiao Fu
Thin Solid Films 2003 Volume 424(Issue 2) pp:283-290
Publication Date(Web):31 January 2003
DOI:10.1016/S0040-6090(02)01118-5
Polythiophene (PT), poly (3-chlorothiophene) and poly (3-methylthiophene) have been electrochemically synthesized by direct oxidative polymerization of corresponding monomers at stainless steel electrode and in boron trifluoride diethyl etherate solution. The as-grown PT films have been peeled off from the electrode surfaces and characterized by resonance Raman spectroscopy in the temperature scale of 78–573 K. During the heating process, the Raman bands related to the oxidized species decreased gradually, mainly due to the effects of oxygen and moisture in air. Finally, the polymers changed into the neutral states and then decomposed. During the cooling process, the polymer chain segments of the neutral species changed from a disordered (coil-like) to an ordered (rod-like) structure and caused the elongation of conjugated chain length. This led to the dramatic decrease of the Raman intensities of the bands related to the neutral species. On the other hand, the Raman intensities of the bands associated with the oxidized species are nearly independent of temperature. This is mainly because the oxidized species have quinoidic structures and their conformation does not change during the cooling process.
Co-reporter:Feng'en Chen;Xufeng Wu;Liangti Qu;Jiaxin Zhang
Journal of Polymer Science Part A: Polymer Chemistry 2003 Volume 41(Issue 3) pp:449-455
Publication Date(Web):17 DEC 2002
DOI:10.1002/pola.10598
Poly(p-phenylene vinylene) (PPV), poly(2,5-dioctyl-p-phenylene vinylene) (PDOPPV), and poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene] (MEHPPV) were synthesized by a liquid–solid two-phase reaction. The liquid phase was tetrahydrofuran containing 1,4-bis(bromomethyl)benzene, 1,4-bis(chloromethyl)-2,5-dioctylbenzene, or 1,4-bis(chloromethyl)-2-methoxyl-5-(2′-ethylhexyloxy)benzene as the monomer and a certain amount of tetrabutylammonium bromide as a phase-transfer catalyst. The solid phase consisted of potassium hydroxide particles with diameters smaller than 2 mm. The experimental results demonstrated that the reaction conversions of PPV and PDOPPV were fairly high (∼65%), but the conversion of MEHPPV was only 45%. Moreover, gelation was found in the polymerization processes. As a result, PPV was insoluble and PDOPPV and MEHPPV were partially soluble in the usual organic solvents, such as tetrahydrofuran and chloroform. Soluble PDOPPV and MEHPPV were obtained with chloromethylbenzene or bromomethylbenzene as a retardant regent. The molar mass of soluble PDOPPV was measured to be 2 × 104 g mol−1, and that of MEHPPV was 6 × 104 g mol−1. A thin, compact film of MEHPPV was formed via spin coating, and it emitted a yellow light. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 449–455, 2003
Co-reporter:Mingxiao Fu, Feng'en Chen, Jiaxin Zhang and Gaoquan Shi
Journal of Materials Chemistry A 2002 vol. 12(Issue 8) pp:2331-2333
Publication Date(Web):27 Jun 2002
DOI:10.1039/B201405J
Aligned microtubular heterojunctions of poly(p-phenylene)
(PPP) and polythiophene (PTh) were fabricated by successive electrochemical oxidations of benzene and thiophene in freshly distilled boron trifluoride–diethyl ether (BFEE) solution and using a microporous alumina membrane with pores of 200 nm diameter as the template. The morphology and chain structure of the microtubular heterojunctions were studied by scanning and transmission electron microscopies and Raman spectroscopy. The current (I)–voltage (V) curves revealed that the aligned microtubular heterojunctions had a better rectification effect than that of the normal PPP/PTh bilayer heterojunction.
Co-reporter:Jingkun Xu;Jiaxin Zhang;Xiaoyin Hong
Macromolecular Chemistry and Physics 2002 Volume 203(Issue 16) pp:2385-2390
Publication Date(Web):7 JAN 2003
DOI:10.1002/macp.200290012
Substrate-supported polythianaphthene (PTN) films have been electrochemically synthesized by direct oxidation of thianaphthene on platinum or stainless steel electrode in mixed electrolytes of boron trifluoride diethyl etherate (BFEE) and trifluoroacetic acid (TFA). The oxidation potentials of the monomer in these media are considerably lower than those in neutral solvents. Increasing the content of TFA in the mixed electrolytes can effectively decrease the oxidation potential and increase the coupling rate of the monomer. On the other hand, a high TFA concentration can result in a negative effect on the properties of the as-formed polymer. The mixed electrolyte of BFEE + 16.7% TFA was found to be the most suitable medium for the electrosyntheses of PTN. PTN in dedoped state is soluble in usual strong polar organic solvent such as dimethyl sulfoxide (DMSO). Fluorescent spectral studies indicate that the polymer is a blue light emitter.
Co-reporter:Chun Li;Fengen Chen;Jingkun Xu;Zhengjiang Xu;Chun Li;Fengen Chen;Zhengjiang Xu;Jingkun Xu
Journal of Applied Polymer Science 2002 Volume 83(Issue 11) pp:2462-2466
Publication Date(Web):4 JAN 2002
DOI:10.1002/app.10238
Free-standing poly(para-phenylene) (PPP) films have been electrosynthesized by direct oxidation of benzene on stainless steel electrode in mixed e1ectrolytes of boron trifluoride diethy1 etherate (BFEE) and trifluoroacetic acid (TFA). The oxidation potential of the monomer in these media is lower than those in the neutral media. Increasing the content of TFA in the mixed electrolyte can effective1y decrease the oxidation potential and increase the coup1ing rate of the monomer. The films obtained from these media were very shiny and flexible, and could easily be processed into various shapes by conventional mechanical methods. The films had a 1inear chain structure, and their degree of polymerization could be improved by increasing the TFA content in the mixed electrolyte. Moreover, the films had a fairly good thermal stability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2462–2466, 2002
Co-reporter:Fan Wang;Zhengjiang Xu;Jiaxin Zhang;Xiaoyin Hong;Fengen Chen
Journal of Applied Polymer Science 2002 Volume 85(Issue 4) pp:785-791
Publication Date(Web):14 MAY 2002
DOI:10.1002/app.10646
A novel liquid/solid two-phase reaction has been discovered that enables destruction of carbon tetrachloride (CCl4) to a black carbon-based material. The solid phase is potassium hydroxide, and the liquid phase is a dimethyl sulfoxide (DMSO) solution of carbon tetrachloride and contains a certain amount of tetrabutylammonium bromide (TBAB) as the phase-transfer catalyst. The reaction can be carried out at room temperature and under normal pressure. Pyrolysis of the carbon-based materials at 700°C and under a nitrogen atmosphere resulted in the formation of amorphous carbonaceous nanoparticles with diameters in the range of 30–60 nm. The carbonaceous materials have a specific surface area of 430 m2/g and an average pore size of 16 Å. Raman spectral and elemental analysis results show the carbonaceous material consists of sp3 and sp2 carbons and also contains a small amount of hydrogen (H/C = 0.08). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 785–791, 2002
Co-reporter:M. Fu;Y. Zhu;R. Tan;G. Shi
Advanced Materials 2001 Volume 13(Issue 24) pp:
Publication Date(Web):11 DEC 2001
DOI:10.1002/1521-4095(200112)13:24<1874::AID-ADMA1874>3.0.CO;2-M
Co-reporter:Gaoquan Shi;Fengen Chen;Sanxie Wu;Yongfa Zhu;Xiaoying Hong;Wenhua Hou;Liang Ming
Journal of Applied Polymer Science 2001 Volume 81(Issue 1) pp:116-120
Publication Date(Web):18 APR 2001
DOI:10.1002/app.1420
Chlorofluorocarbon-22 (HCClF2) gas can react with acetonitrile to form a halogen-free carbon-based polymer when solid potassium hydroxide particles are present. The reaction can be carried out under normal pressure and at room temperature. The polymer is powdery and amorphous. The structure of the polymer has been studied by elemental analysis, Fourier transform IR, Raman, and mass spectroscopies. The results demonstrate that the polymer has a carbonic backbone. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 116–120, 2001
Co-reporter:Mingpeng Yu, Rui Li, Mingmao Wu, Gaoquan Shi
Energy Storage Materials (November 2015) Volume 1() pp:51-73
Publication Date(Web):1 November 2015
DOI:10.1016/j.ensm.2015.08.004
Lithium–sulfur (Li–S) batteries are one of the advanced energy storage systems with a variety of potential applications. Recently, graphene materials have been widely explored for fabricating Li–S batteries because of their unique atom-thick two-dimensional structure and excellent properties. This review article summarizes the recent achievements on graphene-based Li–S batteries, focusing on the applications of graphene materials in sulfur positive electrodes, lithium negative electrodes, and as interlayers. The challenges and perspectives of Li–S batteries with graphene materials are also discussed.
Co-reporter:Zhe Ji, Ji Chen, Liang Huang and Gaoquan Shi
Chemical Communications 2015 - vol. 51(Issue 14) pp:NaN2809-2809
Publication Date(Web):2015/01/07
DOI:10.1039/C4CC09144B
On the basis of the Diels–Alder reaction of graphite and tetracyanoethylene, graphite has been mechanically exfoliated into graphene adducts in a yield up to 38%. The graphene adduct can restore its conjugated structure via retro-Diels–Alder reaction under mild conditions, exhibiting a high conductivity of 1035 S m−1.
Co-reporter:Zhiyi Yao, Hua Bai, Chun Li and Gaoquan Shi
Chemical Communications 2011 - vol. 47(Issue 26) pp:NaN7433-7433
Publication Date(Web):2011/05/17
DOI:10.1039/C1CC11990G
Colorimetric and fluorescent dual detection of cysteine (Cys) and homocysteine (Hcy) has been realized based on the ionic self-assembly of a cationic polythiophene derivative with aromatic derivatives of Cys and Hcy formed in situ.
Co-reporter:Zhiyi Yao, Xueling Feng, Wenjing Hong, Chun Li and Gaoquan Shi
Chemical Communications 2009(Issue 31) pp:NaN4698-4698
Publication Date(Web):2009/07/06
DOI:10.1039/B904975D
A sensor based on an array of wavelengths of a cationic poythiophene derivative was applied to discriminate fifteen nucleotides along with monophosphate and pyrophosphate with 100% confidence limits.
Co-reporter:Zhiyi Yao, Yugang Li, Chun Li and Gaoquan Shi
Chemical Communications 2010 - vol. 46(Issue 45) pp:NaN8641-8641
Publication Date(Web):2010/10/13
DOI:10.1039/C0CC02678F
A colorimetric strategy based on conjugated polyelectrolyte aggregates has been applied to determine and distinguish anionic, cationic and non-ionic surfactants.
Co-reporter:Hua Bai, Yuxi Xu, Lu Zhao, Chun Li and Gaoquan Shi
Chemical Communications 2009(Issue 13) pp:NaN1669-1669
Publication Date(Web):2009/02/10
DOI:10.1039/B821805F
Graphene sheets were stably dispersed in water by functionalization with sulfonated polyaniline (SPANI), and the composite film of SPANI-functionalized graphene showed improved electrochemical stability and enhanced electrocatalytic activity.
Co-reporter:Zhiyi Yao;Xueling Feng;Chun Li
Chemical Communications 2009(Issue 39) pp:
Publication Date(Web):2009/09/29
DOI:10.1039/B912811E
A sensitive colorimetric and fluorescent probe based on a water-soluble cationic conjugated polyelectrolyte was applied to detect glutathione through an in situ premodification technique.
Co-reporter:Liang Huang, Chun Li and Gaoquan Shi
Journal of Materials Chemistry A 2014 - vol. 2(Issue 4) pp:NaN974-974
Publication Date(Web):2013/11/08
DOI:10.1039/C3TA14511E
We report the fabrication of electrochemical capacitors (ECs) with high energy and power densities based on the compact reduced graphene oxide (rGO)/poly(vinyl pyrrolidone) (PVP) composite films. In these ECs, rGO/PVP composite films were directly used as the electrode material without blending any binders or conductive additives because of their high mechanical strength (121.5 ± 10.8 MPa) and electrical conductivity (247.9 S m−1). The solid-state ECs based on the rGO/PVP composite containing 55% rGO (by weight) showed high gravimetric and volumetric specific capacitances, good rate-capability, excellent flexibility and satisfactory electrochemical stability. Furthermore, the EC based on the composite film containing 71% (by weight) of rGO with an organic electrolyte exhibited a high power density (40 W cm−3) and a high energy density (2.5 mW h cm−3) at a current density of 1 A g−1 by taking account of the volumes of its electrodes and separator.
Co-reporter:Qinqin Zhou, Jian Gao, Chun Li, Ji Chen and Gaoquan Shi
Journal of Materials Chemistry A 2013 - vol. 1(Issue 32) pp:NaN9201-9201
Publication Date(Web):2013/06/06
DOI:10.1039/C3TA11438D
We report the preparation of composite organogels of reduced graphene oxide (rGO) and activated carbon (AC) by a solvothermal reaction and their application as electrodes of electrochemical capacitors (ECs). In these organogels, rGO sheets are assembled into a 3-dimensional (3D) framework for encapsulating AC particles. The 3D interconnected rGO network increased the electrical conductivity and the AC component provided high specific surface areas (SSAs) for the composite organogels. These composite organogels also have stable mechanical properties and can be directly used as electrodes of ECs without using any binding agent and conducting additive. In a practical two-electrode system, the specific capacitance of the ECs based on the composite organogels was tested to be 116.5 ± 2.2 F g−1 at a current density of 1 A g−1 in an organic electrolyte of propylene carbonate (PC) containing 1 M tetraethylammonium tetrafluorobromate (TEABF4). These ECs also exhibited a high energy density of 12.5 Wh kg−1 even at a high power density of 6216 W kg−1. They also showed a much larger volumetric specific capacitance compared with that of the EC based on rGO organogel and a much higher specific capacitance and rate capability than those of the AC-based EC.
Co-reporter:Peihui Luo, Chun Li and Gaoquan Shi
Physical Chemistry Chemical Physics 2012 - vol. 14(Issue 20) pp:NaN7366-7366
Publication Date(Web):2012/04/02
DOI:10.1039/C2CP40767A
Gold@carbon dots composite nanoparticles (Au@CDs) with ultrathin carbon dot (CD) shells of ca. 2 nm were prepared by reducing HAuCl4 with CDs at 100 °C. By adjusting the feeding mass ratio of HAuCl4 to CDs, the average diameters of Au@CDs can be modulated from 8 to 44 nm. The suspension of Au@CDs with an average diameter of ca. 24 nm was applied as a substrate for surface enhanced Raman scattering (SERS) and it exhibited a higher SERS effect for rhodamine 6G (Rh6G) than the suspension of pure Au nanoparticles with nearly the same size. The excellent SERS effect of Au@CDs is mainly attributed to their improved capability of adsorbing the aromatic probe molecules.
Co-reporter:Yiqing Sun, Qiong Wu and Gaoquan Shi
Physical Chemistry Chemical Physics 2011 - vol. 13(Issue 38) pp:NaN17254-17254
Publication Date(Web):2011/08/30
DOI:10.1039/C1CP22409C
Self-assembled graphene organogel (SGO) with 3-dimensional (3D) macrostructure was prepared by solvothermal reduction of a graphene oxide (GO) dispersion in propylene carbonate (PC). This SGO was used as an electrode material for fabricating supercapacitors with a PC electrolyte. The supercapacitor can be operated in a wide voltage range of 0–3 V and exhibits a high specific capacitance of 140 F g−1 at a discharge current density of 1 A g−1. Furthermore, it can still keep a specific capacitance of 90 F g−1 at a high current density of 30 A g−1. The maximum energy density of the SGO based supercapacitor was tested to be 43.5 Wh kg−1, and this value is higher than those of the graphene based supercapacitors with aqueous or PC electrolytes reported previously. Furthermore, at a high discharge current density of 30 A g−1, the energy and power densities of the supercapacitor were measured to be 15.4 Wh kg−1 and 16300 W kg−1, respectively. These results indicate that the supercapacitor has a high specific capacitance and power density, and excellent rate capability.
Co-reporter:Yue Tong, Xiaowen Yu and Gaoquan Shi
Physical Chemistry Chemical Physics 2017 - vol. 19(Issue 6) pp:NaN4826-4826
Publication Date(Web):2017/01/16
DOI:10.1039/C6CP08176B
The development of ecofriendly electrocatalysts with earth-abundant metal elements for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is important for overall water splitting to generate clean and sustainable chemical energy. Here, we report a self-standing cobalt disulfide/graphite foam (CoS2/GF) electrocatalytic electrode for this purpose. It showed high catalytic activities for both the HER and OER, requiring only a cell voltage of 1.74 V to achieve a current density of 20 mA cm−2 for overall water splitting in an alkaline electrolyte. This three-dimensional microporous electrocatalytic electrode is cheap and available in a large area; thus, it is attractive for practical applications.
Co-reporter:Zhiyi Yao, Hua Bai, Chun Li and Gaoquan Shi
Chemical Communications 2010 - vol. 46(Issue 28) pp:NaN5096-5096
Publication Date(Web):2010/06/16
DOI:10.1039/C002188A
The vital role of the charged moieties of monovalent aromatic anions in regulating the aggregation of a cationic conjugated polyelectrolyte was exploited in terms of the hard–soft acid–base principle and its application to colorimetric sensing of taurine was examined.
Co-reporter:Yingru Li, Kaixuan Sheng, Wenjing Yuan and Gaoquan Shi
Chemical Communications 2013 - vol. 49(Issue 3) pp:NaN293-293
Publication Date(Web):2012/11/14
DOI:10.1039/C2CC37396C
A fibre-shaped solid electrochemical capacitor based on electrochemically reduced graphene oxide has been fabricated, exhibiting high specific capacitance and rate capability, long cycling life and attractive flexibility.
Co-reporter:Qinqin Zhou, Yingru Li, Liang Huang, Chun Li and Gaoquan Shi
Journal of Materials Chemistry A 2014 - vol. 2(Issue 41) pp:NaN17494-17494
Publication Date(Web):2014/08/27
DOI:10.1039/C4TA03639E
We report an electrochemical co-deposition method to prepare three-dimensional (3D) porous composites of reduced graphene oxide (rGO) and polyaniline (PANI) with pores vertically oriented on the surfaces of current collectors and used as an electrode material for electrochemical capacitors (ECs). These composites showed much higher areal specific capacitances and greatly improved rate capability than those of PANI. Typically, the rGO/PANI composite film with a thickness of 150 μm exhibited a high areal specific capacitance (Ca, 67.2 mF cm−2), small relaxation time constant (τ0, 316 ms) and good electrochemical stability, promising for the fabrication of a high-rate EC.
Co-reporter:Mingpeng Yu, Rui Li, Yue Tong, Yingru Li, Chun Li, Jong-Dal Hong and Gaoquan Shi
Journal of Materials Chemistry A 2015 - vol. 3(Issue 18) pp:NaN9615-9615
Publication Date(Web):2015/03/23
DOI:10.1039/C5TA00651A
A hair-derived carbon/sulfur composite was prepared via a facile melt-diffusion strategy and successively wrapped with reduced graphene oxide (rGO) sheets by electrostatic self-assembly. This composite was used as the sulfur electrode for lithium–sulfur (Li–S) batteries, exhibiting high capacity, good rate capability, and excellent cyclability. The electrode containing 69.0% (by weight, wt%) sulfur delivered an initial discharge capacity of 1113.2 mA h g−1 and 989.2 mA h g−1 after 300 cycles at a current density of 0.2 C with an average coulombic efficiency of 99.3%. Its capacity retention at 2 C was measured to be 62% with respect to the capacity achieved at 0.2 C. The high-performance of this electrode in Li–S batteries can be attributed to the porous carbon infrastructure, inherent nitrogen-doping and graphene protection. Taking into account the low-cost of raw materials and easy scalable processes, this work features a promising approach to prepare sulfur/carbon composites for high-performance Li–S batteries.
Co-reporter:Shan Chen, Xiaowen Yu, Miao Zhang, Jiamin Cao, Yingru Li, Liming Ding and Gaoquan Shi
Journal of Materials Chemistry A 2015 - vol. 3(Issue 36) pp:NaN18383-18383
Publication Date(Web):2015/08/06
DOI:10.1039/C5TA04823K
An annealing-free hole transport layer based on oxygen deficient molybdenum oxide (MoO3−x) nanosheets was developed for polymer solar cells. It showed performance comparable to that of PEDOT:PSS. For better hole extraction, graphene oxide (GO) was introduced to form a GO/MoO3−x bilayer as a hole transport layer to further improve the device performance.
Co-reporter:Xiaowen Yu, Miao Zhang, Wenjing Yuan and Gaoquan Shi
Journal of Materials Chemistry A 2015 - vol. 3(Issue 13) pp:NaN6928-6928
Publication Date(Web):2015/02/12
DOI:10.1039/C5TA01034A
Water oxidation to evolve oxygen is the key step in water splitting and is related to a variety of energy systems. Here, we report a facile electrodeposition process to immobilize nickel–iron layered double hydroxide (Ni–Fe LDH) nanoplates on three-dimensional electrochemically reduced graphene oxide (3D-ErGO) for water oxidation. This Ni–Fe LDH/3D-ErGO electrode has a three-dimensional interpenetrating network with Ni–Fe nanoplates uniformly decorated on graphene sheets. It has an electrochemically active surface area (EASA) 3.3 times that of conventional planar electrodes. The open porous structure of this electrode also makes its EASA fully accessible to the electrolyte for water oxidation and easy release of oxygen gas. This electrode can be directly used for catalysing the oxygen evolution reaction (OER) in alkaline media without using a binder and conductive additive, exhibiting a small overpotential of 0.259 V and a low Tafel slope of 39 mV dec−1. It outperforms the precious IrO2 catalyst in activity, kinetics, and electrochemical stability.
Co-reporter:Ji Chen, Yao Zhang, Miao Zhang, Bowen Yao, Yingru Li, Liang Huang, Chun Li and Gaoquan Shi
Chemical Science (2010-Present) 2016 - vol. 7(Issue 3) pp:NaN1881-1881
Publication Date(Web):2015/11/26
DOI:10.1039/C5SC03828F
Graphene oxide (GO) sheets with controlled species of oxygen-containing groups are important for fabricating graphene materials with desired structures and properties. Here we report a water-addition modified Hummers method to prepare GO sheets with tunable amounts of hydroxyl and epoxide groups without destroying their structural integrity. This method is simple, effective, and efficient. It can be applied to the mass-production of GO with controlled amounts and species of oxygenated groups, and improve the yields of synthesizing high-quality GO at low temperatures.
Co-reporter:Yiqing Sun, Chun Li, Yuxi Xu, Hua Bai, Zhiyi Yao and Gaoquan Shi
Chemical Communications 2010 - vol. 46(Issue 26) pp:NaN4742-4742
Publication Date(Web):2010/05/26
DOI:10.1039/C001635G
Graphitic carbon nitride, a polymeric catalyst, was immobilized on the surfaces of chemically converted graphene sheets to form a layered composite, which exhibited greatly improved conductivity and electrocatalytic performance on oxygen reduction reaction.
Co-reporter:Cancan Huang, Hua Bai, Chun Li and Gaoquan Shi
Chemical Communications 2011 - vol. 47(Issue 17) pp:NaN4964-4964
Publication Date(Web):2011/03/22
DOI:10.1039/C1CC10412H
A graphene oxide/hemoglobin (GO/Hb) composite hydrogel was prepared for catalyzing a peroxidatic reaction in organic solvents with high yields, exceptional activity and stability.
Co-reporter:Hua Bai, Chun Li, Xiaolin Wang and Gaoquan Shi
Chemical Communications 2010 - vol. 46(Issue 14) pp:NaN2378-2378
Publication Date(Web):2010/03/05
DOI:10.1039/C000051E
Graphene oxide/poly(vinyl alcohol) (GO/PVA) composite hydrogel was prepared and utilized for selective drug release at physiological pH.
Co-reporter:Zhengran Yi, Zheye Zhang, Shuai Wang and Gaoquan Shi
Journal of Materials Chemistry A 2017 - vol. 5(Issue 2) pp:NaN523-523
Publication Date(Web):2016/11/29
DOI:10.1039/C6TA09315A
A bioinspired polydopamine derivative was prepared by self-polymerization of 6-(2-aminoethyl)-3-hydroxypyridin-2(1H)-one (AHPO) in an alkaline aqueous medium. It was used as a precursor to produce nanocapsules of pyridinic N-rich carbon with a desired N doping content by using silica nanoparticles as the template. These N-doped nanocapsules exhibited superior electrocatalytic activity and stability towards the oxygen reduction reaction (ORR), lending an attractive alternative to the Pt catalyst. This work provides an important insight into the rational designing of bioinspired polymers for the development of functional carbon materials with excellent properties.
Co-reporter:Qiong Wu, Yiqing Sun, Hua Bai and Gaoquan Shi
Physical Chemistry Chemical Physics 2011 - vol. 13(Issue 23) pp:NaN11198-11198
Publication Date(Web):2011/05/11
DOI:10.1039/C1CP20980A
2-Aminoanthraquinone (AAQ) molecules were covalently grafted onto chemically modified graphene (CMG), and the AAQ functionalized CMG sheets were self-assembled into macroporous hydrogels for supercapacitor electrodes. The electrode based on the AAQ modified self-assembled graphene hydrogel (AQSGH) showed a high specific capacitance of 258 F g−1 at a discharge current density of 0.3 A g−1, which is much larger than that of a pure graphene hydrogel (193 F g−1). Furthermore, the AQSGH electrode exhibited excellent rate capability and a long cycle life. This is mainly due to the covalently bonded AAQ moieties contributing additional redox capacitance. Furthermore, the highly conductive graphene hydrogel scaffold provided a large specific surface area for forming electric double layers and convenient routes for charge transfer and electrolyte diffusion.
Co-reporter:Yiqing Sun, Shiqi Wang, Chun Li, Peihui Luo, Lei Tao, Yen Wei and Gaoquan Shi
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 24) pp:NaN9913-9913
Publication Date(Web):2013/04/24
DOI:10.1039/C3CP50691F
We report an improved Hummers method for synthesizing graphene quantum dots (GQDs) by directly oxidizing and etching graphite powders. The yield of GQDs is as high as 63 ± 7% (by weight, wt%), suggesting this technique is suitable for producing GQDs on a large scale. The GQDs are nanocrystals with lateral dimensions in the range of 2–4 nm and an average thickness of around 1.3 nm. The emission peaks of as-prepared GQDs can be tuned in the range of 440 to 510 nm by varying the reaction conditions. Their fluorescence quantum yields were tested to be around 1%, which could be further increased to about 3% by hydrothermal treatment. These GQDs have low cytotoxicity and excellent biocompatibility, indicating that they are promising for biological applications.
Co-reporter:Xiluan Wang, Chun Li and Gaoquan Shi
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 21) pp:
Publication Date(Web):
DOI:10.1039/C3CP54058H
Co-reporter:Xiluan Wang and Gaoquan Shi
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 43) pp:NaN28504-28504
Publication Date(Web):2015/10/06
DOI:10.1039/C5CP05212B
Pristine graphene and chemically modified graphenes (CMGs, e.g., graphene oxide, reduced graphene oxide and their derivatives) can react with a variety of chemical substances. These reactions have been applied to modulate the structures and properties of graphene materials, and to extend their functions and practical applications. This perspective outlines the chemistry of graphene, including functionalization, doping, photochemistry, catalytic chemistry, and supramolecular chemistry. The mechanisms of graphene related reactions will be introduced, and the challenges in controlling the chemical reactions of graphene will be discussed.
Co-reporter:Bowen Yao, Chun Li, Jun Ma and Gaoquan Shi
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 29) pp:NaN19545-19545
Publication Date(Web):2015/06/30
DOI:10.1039/C5CP02853A
Graphene oxide frameworks (GOFs) have attracted a great deal of attention because of their unique functional building blocks, and tunable structures and properties. Herein, a series of porphyrin-based GOFs with crystalline lamellar structures were synthesized via esterification between boronic acid groups of porphyrins and hydroxyl groups of GO sheets. These GOFs have ultra-large d-spacings of up to 26.0 Å, and they were reduced by facile electrochemical reduction. The resulting reduced GOFs (rGOFs) can be used as catalysts for oxygen reduction reaction (ORR). Electrochemical reduction improved the conductivities of GOFs, accelerating the charge transfer of ORR. The rGOF with Co-porphyrin showed the most positive onset potential of ORR at 0.89 V (vs. RHE, reversible hydrogen electrode), while the rGOF with Fe-porphyrin exhibited the highest catalytic efficiency through an approximately four-electron process. This study provides a new insight for the development of GOFs using multi-functional macrocyclic molecules, revealing their promising applications in electrocatalysts.
Co-reporter:Rui Li, Miao Zhang, Yingru Li, Ji Chen, Bowen Yao, Mingpeng Yu and Gaoquan Shi
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 16) pp:NaN11110-11110
Publication Date(Web):2016/03/18
DOI:10.1039/C6CP00512H
The microstructures and properties of the carbonaceous matrices in the cathodes of lithium–sulfur (Li–S) batteries have strong effects on their performances. We prepared a ternary composite cathode of mildly reduced less defective graphene oxide (mrLGO), sulfur, and carbon nanotubes (CNTs) by filtration for Li–S batteries. This battery showed a high initial specific capacity of 1219 mA h g−1 at 0.2 C and a stable specific capacity of around 1000 mA h g−1 after 200 cycles with a coulombic efficiency of 99%. Its excellent performance is mainly attributed to the good conductivity and residual oxygen containing groups of mrLGO, and the three-dimensional (3D) framework constructed using mrLGO sheets and CNTs.
Co-reporter:Xiluan Wang, Hua Bai, Zhiyi Yao, Anran Liu and Gaoquan Shi
Journal of Materials Chemistry A 2010 - vol. 20(Issue 41) pp:NaN9036-9036
Publication Date(Web):2010/09/09
DOI:10.1039/C0JM01852J
Composite films of chitosan and reduced graphene oxide (RGO) sheets with nacre-like layered structure have been prepared by vacuum filtration of the stable aqueous mixture of both components. The film containing 6 wt% RGO is electrically conductive with a conductivity of 1.2 S m−1. Furthermore, it is mechanically strong and ductile; its Young's modulus, tensile strength and elongation at break were measured to be 6.3 ± 0.2 GPa, 206 ± 6 MPa and 6.5 ± 0.6%, respectively. These values partly exceed those of nacre. The high mechanical and electrical properties of chitosan/RGO composite films are mainly attributed to the uniform dispersion of RGO nanofillers in the polymer matrices to form a compact layered structure.
Co-reporter:Lu Zhao, Lei Tong, Chun Li, Zhongze Gu and Gaoquan Shi
Journal of Materials Chemistry A 2009 - vol. 19(Issue 11) pp:NaN1658-1658
Publication Date(Web):2009/02/04
DOI:10.1039/B819831D
Polypyrrole (PPy) films with inverse opal structures were synthesized by electrochemical polymerization of pyrrole using colloidal crystals as the template. The actuators based on these films exhibited higher actuation rates than those of the actuators made from flat PPy films at a given actuation potential. The nanosized caves of the inverse opal can trap particles with diameters smaller than their orifices, whereas the particles with diameters larger than those of cave orifices only can be adhered on the surfaces of actuators. The particles can be seized and released through electrochemical actuation. Furthermore, the particles with diameters smaller or larger than those of cave orifices can be separated from their mixtures.
Co-reporter:Yang Zhao, Hua Bai, Yue Hu, Yan Li, Liangti Qu, Shaowen Zhang and Gaoquan Shi
Journal of Materials Chemistry A 2011 - vol. 21(Issue 36) pp:NaN13983-13983
Publication Date(Web):2011/08/08
DOI:10.1039/C1JM12014J
Two-dimensional polyaniline (PANI) nanosheets have been prepared inductively by electropolymerization of aniline monomer in an aqueous electrolyte containing sulfonated PANI-functionalized graphenes (SPANI-Gs). The SPANI-G aqueous solution is used directly as the electrolyte for electropolymerization of aniline. The formation of PANI nanosheets depends strongly on the aniline monomer concentration and the as-prepared nanosheets have a thickness of ca. 10 nm. Morphologic characterization reveals the resultant samples are stacked loosely on the surface of electrodes with a large surface area accessible to electrolyte. Electrochemical investigation has shown that the PANI nanosheets formed in the presence of SPANI-Gs had a large specific capacitance of 372 F g−1 at a current density of 0.3 A g−1, five times higher than that of a normal PANI film synthesized in the absence of SPANI-Gs, showing the great potential for energy storage applications.
Co-reporter:Yuanwei Gao, Hua Bai and Gaoquan Shi
Journal of Materials Chemistry A 2010 - vol. 20(Issue 15) pp:NaN2998-2998
Publication Date(Web):2010/02/22
DOI:10.1039/B924992C
A highly fluorescent conjugated oligomer, oligo(1-methoxyl pyrene) (OMOPr), was synthesized via electrochemical polymerization and its structure was studied by UV-vis spectroscopy, MALDI-TOF mass spectroscopy and ab initio calculation. The organic solutions of OMOPr emit strong blue lights and show solvatochromic effect, while these fluorescence emissions are quenched upon chain aggregation in its dry films. On the basis of these phenomena, a turn-on fluorescence sensor was fabricated and it can be used for detecting volatile aromatic compounds (VACs).
Co-reporter:Yuxi Xu, Kaixuan Sheng, Chun Li and Gaoquan Shi
Journal of Materials Chemistry A 2011 - vol. 21(Issue 20) pp:NaN7380-7380
Publication Date(Web):2011/04/09
DOI:10.1039/C1JM10768B
Mildly oxidized graphene oxide (MOGO) was achieved by chemical exfoliation of graphite through a modified Hummers' method. The MOGO is not only able to be stably dispersed in water at a high concentration (1 mg mL−1), but also preserves the highly crystalline structure of the conjugated carbon framework. Thus, the MOGO can be used as a low-defect precursor to prepare highly conductive graphene by chemical reduction. The electrical conductivity of hydrazine or hydriodic acid reduced MOGO was measured to be 169 or 405 S cm−1. This value is about 3 times that of the chemically converted graphene (CCG) prepared by reducing the conventional graphene oxide via Hummers' method with the same reducing agent. This work not only develops a facile route to high-throughput preparation of processable high-quality CCG, but also provides a deeper understanding of the crucial influence of the degree of oxidation of graphene oxide on the electrical properties of its reduced product.
Co-reporter:Hua Bai, Kaixuan Sheng, Pengfei Zhang, Chun Li and Gaoquan Shi
Journal of Materials Chemistry A 2011 - vol. 21(Issue 46) pp:NaN18658-18658
Publication Date(Web):2011/10/25
DOI:10.1039/C1JM13918E
Graphene oxide/conducting polymer (GO/CP) composite hydrogels were prepared by in situ chemical polymerization of corresponding aromatic monomers in aqueous dispersions of GO sheets. GO/polypyrrole (PPy), GO/poly(3,4-ethylenedioxythiophene) (PEDOT) and GO/polyaniline (PANi) hydrogels were obtained by this technique, and the mechanism of gelation was discussed. Among them, GO/PPy composite hydrogels were tested to have low critical hydrogel concentrations (<1%, by weight), high storage moduli (>10 kPa) and electrical conductivity, and strong electrochemical activity. A gas sensor based on a typical GO/PPy hydrogel showed high sensitivity towards ammonia gas.
Co-reporter:Yiqing Sun, Qiong Wu, Yuxi Xu, Hua Bai, Chun Li and Gaoquan Shi
Journal of Materials Chemistry A 2011 - vol. 21(Issue 20) pp:NaN7160-7160
Publication Date(Web):2011/04/04
DOI:10.1039/C0JM04434B
Flexible mesoporous graphitic films with high conductivities were prepared by graphitizing the composite films of graphene oxide (GO) and nanodiamond (ND). After graphitization, ND was changed into onion-like carbon (OC) and GO was reduced to conductive graphene. In the graphitic films, OC nanoparticles were sandwiched between thermally reduced graphene oxide (or graphene) sheets, which not only prevented the aggregation of graphene sheets, but also formed mesopores. The maximum specific surface area of the porous graphitic films was measured to be around 420 m2 g−1 and the diameters of their pores were mostly in the range of 2–11 nm. Furthermore, they are highly conductive with conductivities in the range of 7400 to 20300 S m−1. These films are flexible and can be mechanically shaped into the desired structures. Thus, they can be directly used as the electrodes of supercapacitors without the addition of a polymer binder or a conductive additive. The supercapacitors showed a long cycling life and their specific capacitance was optimized to be 143 F g−1 at a discharge rate of 0.2 A g−1.
Co-reporter:Yuxi Xu and Gaoquan Shi
Journal of Materials Chemistry A 2011 - vol. 21(Issue 10) pp:NaN3323-3323
Publication Date(Web):2010/10/21
DOI:10.1039/C0JM02319A
Chemically modified graphenes (CMGs) are unique building blocks for “bottom up” nanotechnology because of their single-atom thickness, two-dimensional conjugated structure, and exceptional physical and chemical properties. Various hierarchical structures and functional nanocomposites based on CMGs have been prepared by self-assembly. Here, we review the recent advances in the assembly of CMGs in solution or at interfaces, and demonstrate the wide application of the resulting materials.
Co-reporter:Yiqing Sun, Chun Li and Gaoquan Shi
Journal of Materials Chemistry A 2012 - vol. 22(Issue 25) pp:
Publication Date(Web):
DOI:10.1039/C2JM31525D
Co-reporter:Li Zhang, Chun Li, Anran Liu and Gaoquan Shi
Journal of Materials Chemistry A 2012 - vol. 22(Issue 17) pp:NaN8443-8443
Publication Date(Web):2012/03/19
DOI:10.1039/C2JM16552J
Graphene oxide/polypyrene (GO/PPr) composite films were prepared by electrochemical co-deposition of GO and PPr from the organic electrolyte of propylene carbonate (PC). The effects of the GO content in the electrolyte and the deposition charge density on the formation of GO/PPr composite films were studied. Blending with GO improved the mechanical properties of the powdery PPr and gave the composite a continuous and porous morphology with an uninterrupted conducting phase. A chemoresistor-type vapor sensor based on the GO/PPr composite film demonstrated a fast, linear and reversible response to toluene with a high normalized sensitivity of 9.87 × 10−4 ppm−1. The mechanism of sensing the organic vapors with the GO/PPr composite film was also discussed.
Co-reporter:Wenjing Yuan and Gaoquan Shi
Journal of Materials Chemistry A 2013 - vol. 1(Issue 35) pp:NaN10091-10091
Publication Date(Web):2013/06/26
DOI:10.1039/C3TA11774J
Graphene materials have been widely explored for the fabrication of gas sensors because of their atom-thick two-dimensional conjugated structures, high conductivity and large specific surface areas. This feature article summarizes the recent advancements on the synthesis of graphene materials for this purpose and the techniques applied for fabricating gas sensors. The effects of the compositions, structural defects and morphologies of graphene-based sensing layers and the configurations of sensing devices on the performances of gas sensors will also be discussed.
Co-reporter:Mingpeng Yu, Wenjing Yuan, Chun Li, Jong-Dal Hong and Gaoquan Shi
Journal of Materials Chemistry A 2014 - vol. 2(Issue 20) pp:NaN7366-7366
Publication Date(Web):2014/02/21
DOI:10.1039/C4TA00234B
A graphene–sulfur (G–S) composite was conformally coated with an ultrathin Al2O3 film via atomic layer deposition (ALD) and used as the cathode of a lithium–sulfur (Li–S) battery. The G–S composite cathode with an ALD-Al2O3 coating delivered a high specific capacity of 646 mA h g−1 after 100 charge–discharge cycles at 0.5 C, and this value is about twice that of the bare G–S composite. The rate capability and coulombic efficiency of the G–S composite electrode were also greatly increased. The ALD-Al2O3 coating worked as an artificial barrier to suppress the dissolution of polysulfides and alleviate the shuttle effect; thus, it effectively improved the performance of a G–S composite cathode in a Li–S battery.
Co-reporter:Yue Zhuang, Wenjing Yuan, Liu Qian, Shan Chen and Gaoquan Shi
Physical Chemistry Chemical Physics 2017 - vol. 19(Issue 20) pp:NaN12881-12881
Publication Date(Web):2017/04/18
DOI:10.1039/C7CP01646H
Thin films of a thiocyanate ion (SCN−)-doped organometal halide perovskite, CH3NH3PbI3−x(SCN)x, were used as a sensing material for developing high-performance gas sensors. The CH3NH3PbI3−x(SCN)x-based chemiresistor-type sensor can sensitively and selectively detect acetone and nitrogen dioxide (NO2) at room temperature with high sensitivities of 5.6 × 10−3 and 5.3 × 10−1 ppm−1. The limits of detection for acetone and NO2 were measured to be 20 ppm and 200 ppb. This sensor also exhibited excellent repeatability, and its environmental stability was greatly improved by doping the perovskite with SCN− ions.
