Co-reporter:Xiaowei Xu, Hang Chu, Zhuqing Zhang, Pei Dong, Robert Baines, Pulickel M. Ajayan, Jianfeng Shen, and Mingxin Ye
ACS Applied Materials & Interfaces September 27, 2017 Volume 9(Issue 38) pp:32756-32756
Publication Date(Web):September 7, 2017
DOI:10.1021/acsami.7b09866
High-performance active materials for energy-storage and energy-conversion applications require a novel class of electrodes: ones with a structure conducive to conductivity, large specific surface area, high porosity, and mechanical robustness. Herein, we report the design and fabrication of a new ternary hybrid aerogel. The process entails an in situ assembly of 2D WSe2 nanosheets and NiFe-LDH nanosheets on a 3D N,S-codoped graphene framework, accomplished by a facile hydrothermal method and electrostatic self-assembly technology. The obtained nanocomposite architecture maximizes synergistic effects among its three 2D-layer components. To assess the performance of this hybrid material, we deployed it as an advanced electrode in overall water splitting and in a supercapacitor. Results in both scenarios attest to its excellent electrochemical properties. Specifically, serving as a catalyst in an oxygen evolution reaction, our nanocomposite requires overpotentials of 1.48 and 1.59 V to obtain current densities of 10 and 100 mA cm–2, respectively. The hybrid material also efficiently electrocatalyzes hydrogen evolution reactions in base solution, necessitating overpotentials of −50 and −237 mV for current densities of 1.0 and 100 mA cm–2, respectively. The 3D hybrid, when applied to a symmetric supercapacitor device, achieves 125.6 F g–1 capacitance at 1 A g–1 current density. In summary, our study elucidates a new strategy to maximize efficiency via synergetic effects that is likely applicable to other 2D materials.Keywords: 3D structure; hybrid aerogel; N,S-rGO/WSe2/NiFe-LDH; overall water splitting; supercapacitors;
Co-reporter:Yu Pei, Yang Yang, Fangfang Zhang, Pei Dong, Robert Baines, Yuancai Ge, Hang Chu, Pulickel M. Ajayan, Jianfeng Shen, and Mingxin Ye
ACS Applied Materials & Interfaces September 20, 2017 Volume 9(Issue 37) pp:31887-31887
Publication Date(Web):August 29, 2017
DOI:10.1021/acsami.7b09282
Synthesis of highly efficient and robust catalysts with earth-abundant resources for overall water splitting is essential for large-scale energy conversion processes. Herein, a series of highly active and inexpensive Co–Ni–P films were fabricated by a one-step constant current density electrodeposition method. These films were demonstrated to be efficient bifunctional catalysts for both H2 and O2 evolution reactions (HER and OER), while deposition time was deemed to be the crucial factor governing electrochemical performance. At the optimal deposition time, the obtained Co–Ni–P-2 catalyst performed remarkably for both HER and OER in alkaline media. In particular, it requires −103 mV overpotential for HER and 340 mV for OER to achieve the current density of 10 mA cm–2, with corresponding Tafel slopes of 33 and 67 mV dec–1. Moreover, it outperforms the Pt/C//RuO2 catalyst and only needs −160 mV (430 mV) overpotential for HER (OER) to achieve 200 mA cm–2 current density. Co–Ni–P electrodes were also conducted for the proof-of-concept exercise, which were proved to be flexible, stable, and efficient, further opening a new avenue for rapid synthesis of efficient, flexible catalysts for renewable energy resources.Keywords: Co−Ni−P film; electrodeposition; flexible; HER; OER;
Co-reporter:Zheng Cui;Yuancai Ge;Hang Chu;Robert Baines;Pei Dong;Jianhua Tang;Yang Yang;Pulickel M. Ajayan;Jianfeng Shen
Journal of Materials Chemistry A 2017 vol. 5(Issue 4) pp:1595-1602
Publication Date(Web):2017/01/24
DOI:10.1039/C6TA09853C
Fabrication of stable, efficient, and inexpensive bifunctional electro-catalysts for water splitting has become increasingly attractive. Herein, for the first time, the direct growth of Mo-doped Ni3S2 on Ni foams using sodium molybdate as the Mo source at different temperatures is demonstrated. Effects of temperature on the morphology and water splitting performance of Mo-doped Ni3S2 were discussed in detail. It is found that the atomic stoichiometric ratios of Mo and Ni can be controlled by the adjusting of reaction temperature, while the obtained electro-catalysts demonstrate various morphologies, capacitances and chemisorption free energies of hydrogen, which lead to different current densities and hydrogen evolution efficiencies. The electro-catalyst synthesized at 200 °C (200-SMN/NF) demonstrates the best regular morphology and electrochemical properties. When employed in oxygen evolution reactions, 200-SMN/NF demonstrates a low over-potential of 180 mV at 100 mA cm−2. Adapting it as a bifunctional electro-catalyst, a current density of 10 mA cm−2 at a very low cell voltage of 1.53 V and cycling lifespan of more than 15 h was delivered. Further results indicated elevated hydrogen evolution reaction activity, consisting of a moderate 278 mV over-potential at a 100 mA cm−2 hydrogen production current density, a small 72.9 mV dec−1 Tafel slope, and a superior current density compared to that of precious catalyst Pt/C (40%) after −0.53 V. These results underscore the fact that 200-SMN/NF is a high-performance, precious-metal-free electro-catalyst, and provide the foundation for exciting opportunities in water splitting applications.
Co-reporter:Yu Pei, Xiaoguang Li, Hang Chu, Yuancai Ge, Pei Dong, Robert Baines, Liyuan Pei, Mingxin Ye, Jianfeng Shen
Talanta 2017 Volume 165() pp:44-51
Publication Date(Web):1 April 2017
DOI:10.1016/j.talanta.2016.12.015
•Cookie-like Bi2S3/Bi2MoO6 was obtained via ion exchange engineering.•The formation process and mechanism of Bi2S3/Bi2MoO6 were deeply investigated.•Bi2S3/Bi2MoO6 exhibit enhanced photocatalytic and gas sensing properties.Developing efficient visible-light-driven photocatalysts will advance alternative energy technologies, ultimately curbing the environmental pollution associated with fossil fuels. In this work, Bi2S3/Bi2MoO6 photocatalysts with a heterogeneous cookie-like structure were prepared for the first time by in-situ anion exchange at relatively low temperatures. The catalysts exhibited enhanced photocatalytic activity, which we attributed to the photocurrent response, a diminished recombination rate of photogenerated electron-hole pairs, and the existence of a large heterojunction interface. These governing factors were discerned by photoelectrochemical measurements, calculated energy band positions and photoluminescence spectra. Bi2S3/Bi2MoO6 nanocomposites also exhibit better performance in response to gas than bare Bi2MoO6 according to gas sensing tests. Our work, in relaying a feasible method to synthesize Bi2S3/Bi2MoO6-based heterojunction superstructures, and documents a universal preparation method of synthetic heterogeneous complexes, and provides necessary groundwork for the development of next generation semiconductor photocatalytic technology and gas sensor.
Co-reporter:Jianfeng Shen;Yu Pei;Man Wang;Yuancai Ge;Pei Dong;Junhua Yuan;Robert Baines;Pulickel M. Ajayan
Advanced Materials Interfaces 2017 Volume 4(Issue 4) pp:
Publication Date(Web):2017/02/01
DOI:10.1002/admi.201600847
A facile route toward simultaneous liquid phase exfoliation and functionalization of 2D materials with amphiphilic MoS2 nanosheets is established. This scalable and low-cost exfoliation process can be applied to myriad 2D materials. Furthermore, the addition of small amounts of exfoliated 2D materials greatly improves the mechanical and thermal properties of the resulting nanocomposites.
Co-reporter:Jianfeng Shen;Jingjie Wu;Liyuan Pei;Marco-Tulio F. Rodrigues;ZhuQing Zhang;Fangfang Zhang;Xiang Zhang;Pulickel M. Ajayan
Advanced Energy Materials 2016 Volume 6( Issue 13) pp:
Publication Date(Web):
DOI:10.1002/aenm.201600341
3D CoNi2S4-graphene-2D-MoSe2 (CoNi2S4-G-MoSe2) nanocomposite is designed and prepared using a facile ultrasonication and hydrothermal method for supercapacitor (SC) applications. Because of the novel nanocomposite structures and resultant maximized synergistic effect among ultrathin MoSe2 nanosheets, highly conductive graphene and CoNi2S4 nanoparticles, the electrode exhibits rapid electron and ion transport rate and large electroactive surface area, resulting in its amazing electrochemical properties. The CoNi2S4-G-MoSe2 electrode demonstrates a maximum specific capacitance of 1141 F g−1, with capacitance retention of ≈108% after 2000 cycles at a high charge–discharge current density of 20 A g−1. As to its symmetric device, 109 F g−1 at a scan rate of 5 mV s−1 is exhibited. This pioneering work should be helpful in enhancing the capacitive performance of SC materials by designing nanostructures with efficient synergetic effects.
Co-reporter:Jianfeng Shen, Yu Pei, Pei Dong, Jin Ji, Zheng Cui, Junhua Yuan, Robert Baines, Pulickel M. Ajayan and Mingxin Ye
Nanoscale 2016 vol. 8(Issue 18) pp:9641-9647
Publication Date(Web):07 Apr 2016
DOI:10.1039/C6NR00583G
Few-layered polyelectrolyte functionalized MoS2 nanosheets were obtained for the first time through in situ polymerization of MoS2 nanosheets with poly(acrylic acid) and poly(acrylamide), both of which demonstrated excellent dispersibility and stability in water. After designing and optimizing the components of this series of polyelectrolyte functionalized MoS2 nanosheets, by exploiting the electrostatic interactions present in the modified MoS2 nanosheets, we further created a series of layer-by-layer (LBL) self-assembling MoS2-based films. To this end, uniform MoS2 nanosheet-based LBL films were precisely deposited on substrates such as quartz, silicon, and ITO. The polyelectrolyte functionalized MoS2 nanosheet assembled LBL film-modified electrodes demonstrated enhanced electrocatalytic activity for H2O2. As such, they are conducive to efficient sensors and advanced biosensing systems.
Co-reporter:Jianfeng Shen, Jin Ji, Pei Dong, Robert Baines, Zhuqing Zhang, Pulickel M. Ajayan and Mingxin Ye
Journal of Materials Chemistry A 2016 vol. 4(Issue 22) pp:8844-8850
Publication Date(Web):09 May 2016
DOI:10.1039/C6TA03111K
Ternary electrode materials based on graphene, FeNi2S4, and transition metal dichalcogenides (TMDs) were obtained via a one-pot synthesis method. Compared to binary materials, FeNi2S4–graphene (g)–2D-TMD nanocomposites exhibited better performance, which is a direct consequence of their unique ternary structures and the induced synergistic effect among their three components—ultrathin TMD nanosheets, highly conductive graphene networks, and FeNi2S4 nanoparticles. With the fabricated materials, we constructed electrodes to assess the electrochemical performance. The results are promising: the materials exhibited rapid electron and ion transport rates and large electroactive surface areas, testifying to their excellent electrochemical properties. In particular, the FeNi2S4–g–MoSe2 electrode demonstrated a maximum specific capacitance of 1700 F g−1 at a current density of 2 A g−1 (8.5 F cm−2 at a current density of 10 mA cm−2) and a capacitance retention of approximately 106% after 4000 cycles at a charge–discharge current density of 2 A g−1. These electrochemical results indicate that the ternary composite, FeNi2S4–g–MoSe2, is a promising candidate electrode material for high-performance supercapacitors.
Co-reporter:Jianhua Tang, Yuancai Ge, Jianfeng Shen and Mingxin Ye
Chemical Communications 2016 vol. 52(Issue 7) pp:1509-1512
Publication Date(Web):25 Nov 2015
DOI:10.1039/C5CC09402J
CuCo2S4 nanoparticles demonstrating outstanding electrochemical performances were firstly synthesized through a simple solvothermal approach without using any templates. CuCo2S4 synthesized in glycerol (CuCo2S4–glycerol) fulfills an ultrahigh capacitance of 5030 F g−1 at 20 A g−1 in a polysulfide electrolyte.
Co-reporter:Jianfeng Shen, Pei Dong, Robert Baines, Xiaowei Xu, Zhuqing Zhang, Pulickel M. Ajayan and Mingxin Ye
Chemical Communications 2016 vol. 52(Issue 59) pp:9251-9254
Publication Date(Web):17 Jun 2016
DOI:10.1039/C6CC03699F
Novel ternary electrode materials based on graphene, NiCo2S4, and transition metal dichalcogenides (TMDs) were designed and fabricated with the intention of exploiting synergistic effects conducive to supercapacitive energy storage. Compared to NiCo2S4-g-MoSe2, the NiCo2S4-g-MoS2 electrode exhibited higher specific capacitance, enhanced rate capability (1002 F g−1 even at 5 A g−1, 6.01 F cm−2 at a current density of 25 mA cm−2) and cycling stability (94.8% retention of its original capacity after cycling 4000 times). The mechanism was proposed and this pioneering work will be helpful in making judicious choices of which 2D materials to be selected for supercapacitor applications in the future.
Co-reporter:Xiaowei Xu, Yuancai Ge, Man Wang, Zhuqing Zhang, Pei Dong, Robert Baines, Mingxin Ye, and Jianfeng Shen
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 28) pp:18036-18042
Publication Date(Web):June 29, 2016
DOI:10.1021/acsami.6b03849
Herein, we describe the preparation and testing of Co-doped FeSe2 hybridized with graphene (Fe1–xCoxSe2/RGO), a high-active yet stable electrocatalyst for hydrogen evolution reactions (HERs) in acidic solutions. First, we systematically analyze the composition and morphology of Fe1–xCoxSe2/RGO and attribute its excellent electrochemical performance to its unique architecture—a base of highly conductive graphene with fully exposed active edges that enhances conductivity and facilitates ion/electron transfer. Our experimental measurements indicate elevated HER activity with a moderate overpotential of ∼166 mV at a hydrogen production current density of 10 mA cm–2, a small Tafel slope of ∼36 mV dec–1, and long cycling lifespan more than 20 h. The promising results, in addition to the fact that Fe1–xCoxSe2/RGO is a high-performance, precious-metal-free electrocatalyst, pave the way for exciting opportunities in renewable hydrogen production applications.
Co-reporter:Yang Yang, Liyuan Pei, Xiaowei Xu, Jingxuan Xu, Jianfeng Shen, Mingxin Ye
Electrochimica Acta 2016 Volume 221() pp:56-61
Publication Date(Web):10 December 2016
DOI:10.1016/j.electacta.2016.10.150
Nanostructured Copper oxides are promising materials for supercapacitors due to their high theoretical capacitance, low cost and environment friendly properties, especially for those prepared via template-free method. In this work, an in-situ growth of self-assembled 3D Cu2O@Cu foams nanocomposite without template has been developed and the synthesis mechanism has been discussed in detail. The electrode exhibits a high capacitance of 0.66 F cm−2 (about 200 F g−1) and significant stability (after 12000 times cycling, remaining 87.9% of the initial value). Extraordinary performances and relative cost of the raw material indicate its potential in commercial applications for energy storage.
Co-reporter:Xiaowei Xu, Liyuan Pei, Yang Yang, Jianfeng Shen, Mingxin Ye
Journal of Alloys and Compounds 2016 Volume 654() pp:23-31
Publication Date(Web):5 January 2016
DOI:10.1016/j.jallcom.2015.09.108
•NiWO4/RGO composite was successfully prepared through a facile solvothermal method.•The NiWO4/RGO composite shows a high specific capacitance of 1031.3 F g−1.•Enhanced electrical conductivity leads to superior electrochemical performance.NiWO4/reduced graphene oxide (NWG) nanocomposite was successfully synthesized through a facile one-pot solvothermal method for the first time. The resulting nanocomposite is composed of NiWO4 nanoparticles that are uniformly attached on graphene sheets by in situ reducing. The as-prepared NWG composite has been systematically characterized by Powder X-ray diffraction, Fourier transform infrared spectra, Raman spectroscopy, Thermogravimetric analysis, Scanning electron microscopy, Transmission electron microscopy, X-ray photoelectron spectra, and Brunauer–Emmett–Teller analysis. The capacitive performances of the as-prepared NWG composite as electrode material are investigated. It is found that the NWG composite exhibits a high specific capacitance up to 1031.3 F g−1 at a current density of 0.5 A g−1. The greatly enhanced capacitive performance of the NWG electrode can be attributed to the synergetic effect of NiWO4 nanoparticles and RGO, which provides conducting channels and active sites. The cyclic stability tests demonstrated no decreases of its initial values after 5000 cycles, suggesting that such hybrid electrode possesses a great potential application in energy-storage devices.
Co-reporter:Jianfeng Shen, Xiaowei Xu, Pei Dong, Zhuqing Zhang, Robert Baines, Jin Ji, Yu Pei, Mingxin Ye
Ceramics International 2016 Volume 42(Issue 7) pp:8120-8127
Publication Date(Web):15 May 2016
DOI:10.1016/j.ceramint.2016.02.016
In this paper, we described a simple two–step method for preparing needle-like CoNi2S4/CNT/graphene nanocomposite with robust connection among its ternary components. The prepared CoNi2S4/CNT/graphene nanocomposite has been thoroughly characterized by spectroscopic (Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy), X-ray diffraction and thermogravimetric analysis. Microscopy techniques (scanning electron microscopy–energy dispersive spectroscopy and transmission electron microscopy) were employed to probe the morphological structures. The electrochemical properties of the as-prepared 3D architectures were investigated with three and two-electrode systems. In addition to its high specific capacitance (710 F g−1 at 20 A g−1), after charging–discharging for 2000 cycles, the electrode still maintained the capacity retention of about 82%. When used as the active electrode material for supercapacitors, the fabricated CoNi2S4–g–CNT nanostructure exhibited excellent specific capacitance and good rate capability, making it a promising candidate for next-generation supercapacitors.
Co-reporter:Liyuan Pei, Yang Yang, Hang Chu, Jianfeng Shen, Mingxin Ye
Ceramics International 2016 Volume 42(Issue 4) pp:5053-5061
Publication Date(Web):March 2016
DOI:10.1016/j.ceramint.2015.11.178
Graphene aerogel (GA) supported flower-like ferrous disulfide (FeS2) composite was synthesis by a two-step self-assembly method using eco-friendly and low-cost precursors. The formation of well-crystallized pyrite FeS2 and the reduction of graphene oxide (GO) was demonstrated by X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy. According to the scanning electron microscopy images, the flower-like FeS2 distributes uniformly on the inter-linking GA networks. The electrochemical tests indicate that the as-prepared GA-FeS2 exhibits enhanced specific capacitance (313.6 F/g at the current density of 0.5 A/g), which is almost twice as high as that of bare FeS2 (163.5 F/g). It is noticed that this composite also has excellent cyclability (88.2% retention after 2000 cycles at 10 A/g) and low transfer resistance. A symmetric supercapacitor device with wide potential range was assembled using GA-FeS2, while its energy density could reach 22.86 Wh/kg. The excellent specific capacitance, good rate capability, and high energy density make it a promising candidate for next generation supercapacitors.
Co-reporter:Jianhua Tang, Jianfeng Shen, Na Li, Mingxin Ye
Journal of Alloys and Compounds 2016 Volume 666() pp:15-22
Publication Date(Web):5 May 2016
DOI:10.1016/j.jallcom.2015.12.219
•The MnWO4/RGO was first prepared through a facile hydrothermal route.•MnWO4/RGO composite show much higher specific capacitances than pure MnWO4.•The electrochemical properties of MnWO4/RGO arise from the synergistic effect.The layered MnWO4/reduced graphene oxide (MnWO4/RGO) was prepared through a facile one-pot low-temperature hydrothermal route without using any templates. The structure and morphology of MnWO4/RGO nanocomposite were characterized through X-ray diffraction, Raman spectra, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption/desorption and thermo-gravimetric analysis. While its electrochemical behaviors were investigated using cyclic voltammograms, galvanostatic charge/discharge and electrochemical impedance spectroscopy. In the case of three electrode cells, MnWO4/RGO with 7.28 wt% RGO content fulfilled a maximum specific capacitance of 288 F g−1 at 5 mV s−1 with the potential range from −0.35–0.55 V. While in the two electrode cell, it obtained a maximum specific capacitance of 109 F g−1 at 5 mV s−1 and displayed the cycle life of 14.9% capacitance decline after 6000 cycles.
Co-reporter:Xiaoguang Li, Yinle Li, Jianfeng Shen, Mingxin Ye
Ceramics International 2016 Volume 42(Issue 2) pp:3154-3162
Publication Date(Web):1 February 2016
DOI:10.1016/j.ceramint.2015.10.105
Bi2S3/Bi2WO6 semiconductor heterostructures with enhanced visible light photocatalytic activity were firstly prepared through a facile in-situ anion exchange approach at relatively low temperature, using thioacetamide as sulphur source and Bi2WO6 nanosheets as precursors. Bi2S3 nanoparticles decorated on the surface of 2D plate-like Bi2WO6 nanosheets were analyzed by using X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy etc. Photocatalytic experiments indicate that such Bi2S3/Bi2WO6 composites possess higher photocatalytic activity for the degradation of Rhodamine B under visible light irradiation in comparison with pure Bi2S3 or Bi2WO6. Among Bi2S3/Bi2WO6 composites with different contents of Bi2S3, the Bi2S3/Bi2WO6 composite with 30% Bi2S3 exhibits the highest photocatalytic efficiency. Based on the calculated energy band positions and photoluminescence spectrum, it was postulated that enhanced photocatalytic property could be ascribed to the reduction of the recombination rate of photogenerated electron–hole pairs and the heterojunction interface. Moreover, these results suggest that the heterostructured photocatalysts can be potentially applied in environmental protection and waste water treatment.
Co-reporter:Tao Fan, Yinle Li, Jianfeng Shen, Mingxin Ye
Applied Surface Science 2016 Volume 367() pp:518-527
Publication Date(Web):30 March 2016
DOI:10.1016/j.apsusc.2016.01.194
Highlights
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GQD-PVP-CdS composite was prepared for the first time through a facile hydrothermal route.
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GQD-PVP-CdS demonstrated outstanding photoactivity under visible light illumination.
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GQDs and polymeric material are compounded with CdS nanoparticles simultaneously for the first time.
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The addition of GQDs plays pivotal roles in the enhancement of the photoactivity.
Co-reporter:Jianfeng Shen, Jianhua Tang, Pei Dong, Zhuqing Zhang, Jin Ji, Robert Baines and Mingxin Ye
RSC Advances 2016 vol. 6(Issue 16) pp:13456-13460
Publication Date(Web):22 Jan 2016
DOI:10.1039/C5RA25856A
The search for safe and efficient energy storage systems continues to inspire researchers to develop new energy storage materials with excellent performance. Graphene-based three-dimensional (3D) nanostructures are interesting to supercapacitors (SCs) because of their high surface area, ample number of active sites, and good conductivity. This combination of attributes allows for full utilization capacitance of active electrode materials. Herein, three-dimensional CuCo2S4–g–CNT structure was fabricated successfully with the hydrothermal method. Serving as the active electrode, CuCo2S4–g–CNT demonstrated a remarkable specific capacitance (504 F g−1 at the current density of 10 A g−1). Moreover, the as-obtained CuCo2S4–g–CNT hybrid electrode is robust, exhibiting exceptional cycle life, as revealed by galvanostatic charge–discharge studies (retaining 92.3% after 2000 cycles). Its durability is mainly due to the synergistic effects of CuCo2S4, graphene and CNTs. These unique nano-architectures demonstrate potential applications in energy storage electrodes and may indeed spur a new generation of hybrid SCs to bridge the energy gap between SCs and chemical batteries.
Co-reporter:Yuancai Ge, Jingjie Wu, Xiaowei Xu, Mingxin Ye, Jianfeng Shen
International Journal of Hydrogen Energy 2016 Volume 41(Issue 44) pp:19847-19854
Publication Date(Web):26 November 2016
DOI:10.1016/j.ijhydene.2016.08.096
•CoNi2S4 and CuCo2S4 with different morphologies are synthesized successfully.•The overpotential for CoNi2S4 nanorod is only 111 mV to reach 10 mA/cm2.•The overpotential for CuCo2S4 cluster is only 135 mV to reach 10 mA/cm2.•Their catalytic performances are better than monometallic sulfides.In this paper, a facile one-pot method was employed to synthesize CoNi2S4 and CuCo2S4 with various morphologies. The required overpotentials for CoNi2S4 nanorod and CuCo2S4 cluster are only 111 mV and 135 mV, respectively, to reach the current density of 10 mA/cm2. The Tafel slopes for CoNi2S4 nanorod (53 mV/dec) and CuCo2S4 cluster (63 mV/dec) are lower than that for binary systems of CoS2 and NiS2. The CoNi2S4 nanorod shows better long-term durability than CuCo2S4 cluster during the galvanostatic electrolysis. Overall these ternary sulfides exhibit promising activity and fair stability for hydrogen evolution reaction.
Co-reporter:Xiaowei Xu, Yang Yang, Man Wang, Pei Dong, Robert Baines, Jianfeng Shen, Mingxin Ye
Ceramics International 2016 Volume 42(Issue 9) pp:10719-10725
Publication Date(Web):July 2016
DOI:10.1016/j.ceramint.2016.03.192
Abstract
Hierarchical Co3O4@CoWO4/rGO core/shell nanoneedles arrays are successfully grown on 3D nickel foam using a simple, effective method. By virtue of its unique structure, Co3O4@CoWO4/rGO demonstrates an enhanced specific capacitance of 386 F g−1 at 0.5 A g−1 current density. It can be used as an integrated, additive-free electrode for supercapacitors that boasts excellent performance. As illustration, we assemble an asymmetric supercapacitor (ASC) using the as-prepared Co3O4@CoWO4/rGO as the positive electrode and activated carbon as the negative electrode. The optimized ASC displays a maximum energy density of 19.99 Wh kg−1 at a power density of 321 W kg−1. Furthermore, the ASC also presents a remarkably long cycle life along with 88.8% specific capacitance retention after 5000 cycles.
Co-reporter:Dr. Yinle Li;Zhuqing Zhang;Tao Fan;Xiaoguang Li;Jin Ji;Pei Dong;Robert Baines; Jianfeng Shen; Mingxin Ye
ChemPlusChem 2016 Volume 81( Issue 6) pp:564-573
Publication Date(Web):
DOI:10.1002/cplu.201600094
Abstract
This study describes a comparative investigation on the heterogeneous versus homogeneous nature of the Pd-catalyzed Suzuki–Miyaura cross-coupling reaction mechanism with specific magnetic hierarchical core–shell and yolk–shell structures. The hierarchical core–shell Fe3O4@SiO2-Pd@mCeO2 (m=mesoporous) catalyst contains a core of nonporous silica-sheltered magnetite (Fe3O4) nanoparticles (NPs), a transition layer of active palladium (Pd) NPs, and an outer shell of porous ceria (CeO2). The magnetic yolk–shell Fe3O4@h-Pd@mCeO2 (h=hollow) catalyst was prepared by selectively etching the nonporous silica interlayers. Notably, the results of the hot-filtration heterogeneity test, the effect of Pd concentration, and solid-phase poisoning, indicate that the two kinds of catalysts function in Pd-catalyzed Suzuki–Miyaura cross-coupling reactions through different catalytic mechanisms. Moreover, both catalysts demonstrated better catalytic activity than the Fe3O4@SiO2-Pd catalyst. This finding can be ascribed to the outermost CeO2 shell having a high concentration of trivalent cerium and oxygen vacancies, which gives rise to the increased electron density of Pd NPs, and a faster rate-determining step in the oxidative addition reaction for the Suzuki reaction. In addition, we propose a feasible mechanism elucidating the synergistic effect between the supporting CeO2 and active species.
Co-reporter:Man Wang, Xiaowei Xu, Jin Ji, Yang Yang, Jianfeng Shen, Mingxin Ye
Composites Part B: Engineering 2016 Volume 107() pp:1-8
Publication Date(Web):15 December 2016
DOI:10.1016/j.compositesb.2016.09.067
Novolac epoxy resins, with the high glass transition temperature (Tg) and excellent mechanical strength, are widely applied in the molding and sealing compounds for the production of electronic devices. However, weather exposure and environmental elements are inclined to affect their durability severely. This work focuses on the hygrothermal aging process and mechanism of the novolac epoxy resin. The effect of humidity and time in hygrothermal aging on structural and mechanical properties of the novolac epoxy resin was deeply studied. The moisture absorption increases linearly with the square root of aging time, and it follows the Fick's second law. There are two main categories of reactions in hygrothermal aging: the first one is the post curing process, which leads to a larger crosslinking density and a reduced interior stress; while the other is the plasticization and deterioration of epoxy resin attributed to moisture ingress. The combination of above factors leads to a decrease-increase-decrease variation in mechanical properties. This work is believed to benefit the wide and safe application of a certain novolac epoxy resin system in engineering application.
Co-reporter:Jianfeng Shen, Yongmin He, Jingjie Wu, Caitian Gao, Kunttal Keyshar, Xiang Zhang, Yingchao Yang, Mingxin Ye, Robert Vajtai, Jun Lou, and Pulickel M. Ajayan
Nano Letters 2015 Volume 15(Issue 8) pp:5449-5454
Publication Date(Web):July 22, 2015
DOI:10.1021/acs.nanolett.5b01842
Exfoliation of two-dimensional (2D) materials into mono- or few layers is of significance for both fundamental studies and potential applications. In this report, for the first time surface tension components were directly probed and matched to predict solvents with effective liquid phase exfoliation (LPE) capability for 2D materials such as graphene, h-BN, WS2, MoS2, MoSe2, Bi2Se3, TaS2, and SnS2. Exfoliation efficiency is enhanced when the ratios of the surface tension components of the applied solvent is close to that of the 2D material in question. We enlarged the library of low-toxic and common solvents for LPE. Our study provides distinctive insight into LPE and has pioneered a rational strategy for LPE of 2D materials with high yield.
Co-reporter:Xianfu Li, Jianfeng Shen, Na Li, Mingxin Ye
Journal of Power Sources 2015 Volume 282() pp:194-201
Publication Date(Web):15 May 2015
DOI:10.1016/j.jpowsour.2015.02.057
•A facile one-pot solvothermal process was developed to produce γ-MnS/rGO composite.•The prepared γ-MnS/rGO composite shows a high specific capacitance value of 802.5 F g−1 at a current density of 5 A g−1.•The composite electrode exhibits an excellent cycling stability with high capacity retention.γ-MnS/reduced graphene oxide (γ-MnS/rGO) composite was successfully fabricated via a facile one-pot solvothermal route using graphene oxide (GO), thioacetamide (TAA, CH3CSNH2) and MnCl2·4H2O as reactants. It reveals that TAA plays an important role in reducing GO and sulfurizing γ-MnS. The synthesized composite was characterized via X-ray diffraction and scanning electron microscopy for structural and morphological studies. Electrochemical performance was also investigated through cyclic voltammetry and galvanostatic charge–discharge. As for the application of supercapacitors, the γ-MnS/rGO composite shows a great value of 802.5 F g−1 at a current density of 5 A g−1. Furthermore, the capacitance of γ-MnS/rGO has no decrease of its initial values after 2000 cycles. The galvanostatic charge–discharge curve demonstrates the ideal capacitive behavior of γ-MnS/rGO composite electrodes.
Co-reporter:Xiaowei Xu, Jianfeng Shen, Na Li, Mingxin Ye
International Journal of Hydrogen Energy 2015 Volume 40(Issue 38) pp:13003-13013
Publication Date(Web):15 October 2015
DOI:10.1016/j.ijhydene.2015.08.021
•Co/RGO composites were successfully prepared via a facile microwave-assisted route.•Co/RGO composites show much high specific capacitances and good rate capacity.•The superior electrochemical performance is due to the synergetic effect of RGO and Co particles.A series of cobalt nanoparticles/reduced graphene oxide (Co/RGO) composites have been successfully synthesized via a facile microwave-assisted synthetic route for the first time. The synthesized composites are comprised of Co particles that are uniformly anchored onto the surface of graphene sheets by in situ reducing. Powder X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Raman spectroscopy, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), and Brunauer-Emmett-Teller (BET) analysis are performed for systematically characterizing the microstructure and composition of the as-prepared Co/RGO composites. Interestingly, the as-prepared composites show superior electrochemical performance to their counterparts of Co and RGO as electrodes for supercapacitors. As a result, Co/RGO-15 composite exhibits a high specific capacitance of 370.7 F g−1 at 5 mV s−1 in 2 M KOH aqueous solution as well as good rate capability. The excellent electrochemical performances are due to the 3D graphene conductive network and the synergetic effect of RGO and Co particles. Meanwhile, the capacitance retention keeps about 92.3% of the initial value after 2000 cycles at a current density of 2 A g−1, suggesting that such hybrid electrode possesses a great potential application in energy-storage devices.
Co-reporter:Shutong Huang;Jianfeng Shen;Na Li
Journal of Applied Polymer Science 2015 Volume 132( Issue 9) pp:
Publication Date(Web):
DOI:10.1002/app.41530
ABSTRACT
pH- and temperature-responsive semi-interpenetrating nanocomposite hydrogels (NC hydrogels) were prepared with surface-functionalized graphene oxide (GO) as the crosslinker, N-isopropylacrylamide (NIPAM) as the monomer, and chitosan (CS) as an additive. The effects of 3-(trimethoxysilyl)propylmethacrylate-modified GO sheets and CS content on various physical properties were investigated. Results show that PNIPAM/CS/GO hydrogels undergo a large volumetric change in response to temperature. Swelling ratios of PNIPAM/CS/GO hydrogels are much larger than those of the conventional organically crosslinked PNIPAM hydrogels. The deswelling test indicates that the deswelling rate was greatly enhanced by incorporating CS into the hydrogel network and using the surface-functionalized GO as the crosslinker. The pH-sensitivity of PNIPAM/CS/GO hydrogels is evident below their volume phase transition temperature. Moreover, the PNIPAM/CS/GO hydrogels have a much better mechanical property compared with traditional hydrogels even in a high water content of 90%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41530.
Co-reporter:Xianfu Li, Jianfeng Shen, Na Li, Mingxin Ye
Materials Letters 2015 Volume 139() pp:81-85
Publication Date(Web):15 January 2015
DOI:10.1016/j.matlet.2014.10.024
•An easy template-free synthetic approach to the fabrication of graphene/NiS2 composite through a solvothermal process was developed.•Using environmentally-friendly Na2S2O3·5H2O as reducing agent for GO as well as sulfur source for NiS2.•The prepared graphene/NiS2 composite shows a high specific capacitance value of 478.1 F/g at a current density of 0.5 A/g.Graphene/NiS2 composite was obtained through a template-free solvothermal reaction using graphene oxide (GO), Na2S2O3·5H2O and NiCl2·6H2O as reactants. Na2S2O3·5H2O plays an important role as the reducing agent for GO as well as the sulfur source for NiS2. Electrochemical behaviour of the graphene/NiS2 composite was studied through cyclic voltammetry and galvanostatic charge-discharge. As for the applications in supercapacitors, graphene/NiS2 composite shows a great value of 478.1 F/g at a current density of 0.5 A/g. Furthermore, the capacitance of graphene/NiS2 decreases only 10.7% of its initial value after 2000 cycles.
Co-reporter:Weishi Huang;Jianfeng Shen;Na Li
Polymer Engineering & Science 2015 Volume 55( Issue 6) pp:1361-1366
Publication Date(Web):
DOI:10.1002/pen.24076
pH- and temperature-responsive double network hydrogels (DN hydrogels) were prepared by using poly (N-isopropylacrylamide) (PNIPAM) as a tightly crosslinked network (1st network), polyacrylic acid (PAA) as a loosely crosslinked network (2nd network), with clay and graphene oxide as effective crosslinkers and reinforcing fillers. The structure and morphology of the hydrogels were characterized by SEM, FTIR, DSC, and TGA. The synergetic effects of clay, GO and DN structure on various physical properties were investigated. With the increasing of crosslinking densities, the swelling ratios of DN hydrogels gradually decreased by increasing the contents of graphene oxide and PAA. While the DN hydrogels had much better mechanical properties than that of the conventional chemically cross-linked PNIPAM hydrogels. POLYM. ENG. SCI., 55:1361–1366, 2015. © 2015 Society of Plastics Engineers
Co-reporter:Yu Long, Ye Shu, Xiaohua Ma, Minxin Ye
Electrochimica Acta 2014 Volume 117() pp:105-112
Publication Date(Web):20 January 2014
DOI:10.1016/j.electacta.2013.11.106
To overcome the detrimental effects of LiFePO4 on the tap density and volumetric energy density accompanied by conventional carbon-based additives, C-LiFePO4/graphene was successfully prepared via hydrothermal synthesis, followed by heat treatment, and by substitution of superior conductive graphene nanosheets for some conventional carbon. The reduction of graphite oxide and the synthesis of LiFePO4 were carried out simultaneously in mixed ethylene glycol/water medium, facilitating desirable compatibility and architecture of LiFePO4 particles and graphene nanosheets. Due to the synergism of thin carbon coating and graphene matrix with low fraction on the basis of complementary advantages, C-LiFePO4/graphene exhibits superior high-rate performance and favorable energy density, which with a unique structural and geometrical feature that LiFePO4/C nanorods embedded in a matrix built of interweaved graphene nanosheets. The dual coatings exert a significantly energetic impact on the electronic conductivity and lithium ion transport, thus novel composite presented excellent electrochemical properties, which was achieved with reversible capacities of 100 mAh/g at 20 C and 80 mAh/g at 50 C, while preserving a high tap density of 1.76 g/cm3.
Co-reporter:Jianfeng Shen, Xianfu Li, Na Li, Mingxin Ye
Electrochimica Acta 2014 Volume 141() pp:126-133
Publication Date(Web):20 September 2014
DOI:10.1016/j.electacta.2014.07.063
Reduced graphene oxide-nickel cobaltite (RGO-NiCo2O4) nanocomposites have been successfully synthesized by a hydrothermal method with the assistance of Poly (diallyldimethylammonium chloride) (PDDA). PDDA is used as a reducing agent, capping agent and a stabilizer. The prepared RGO-NiCo2O4 nanocomposites have been thoroughly characterized by spectroscopic (Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy) and thermogravimetric analysis. Microscopy techniques (scanning electron microscopy, transmission electron microscopy and atomic force microscopy) were employed to probe the morphological structures as well as to investigate the exfoliation of RGO sheets. The nanocomposites exhibited superior performance to NiCo2O4 as electrodes in pseudocapacitors with capacitance of 676.1 F/g. This is attributed to the increased electrical conductivity and the creation of new active sites due to the synergetic effect of RGO and NiCo2O4 nanoparticles.
Co-reporter:Xiaowei Xu, Jianfeng Shen, Na Li, Mingxin Ye
Electrochimica Acta 2014 150() pp: 23-34
Publication Date(Web):
DOI:10.1016/j.electacta.2014.10.139
Co-reporter:Tie Li, Jianfeng Shen, Na Li, Mingxin Ye
Materials Science and Engineering: C 2014 Volume 39() pp:352-358
Publication Date(Web):1 June 2014
DOI:10.1016/j.msec.2014.03.027
•A novel RGO-CD-Ag hybrid was firstly synthesized by a facile in situ process with the supramolecular β-cyclodextrin (CD) as a conjugation interface.•It was found that the existed CD interface indeed influenced the surface hydrophilic property of the hybrid.•The antibacterial activity of RGO-CD-Ag composites showed a remarkably enhanced performance compared with the contrast nanoparticles.In this study, a novel hydrophilic RGO–CD–Ag hybrid with the supramolecular β-cyclodextrin (CD) as a conjugation interface was fabricated successfully by a facile in situ synthesis process. The results of several characterizations confirmed that the in situ reaction provided a straightforward approach to deposit the CD wrapped Ag nanoparticles onto the CD chemical functionalized RGO sheets through the head-to-head H-bond interactions between the linker CD molecules. Moreover, it was also found that the CD interface that existed indeed influences the structure and performances of RGO–CD–Ag nanocomposite. The analysis of the static contact angle revealed that the surface property of the hybrid could be transformed from hydrophobic to hydrophilic feature, which highly improved the aqueous dispersibility. And then, the bactericidal test of RGO–CD–Ag was demonstrated and clearly showed the strongest antibacterial activity against Gram-negative and Gram-positive bacteria among all samples. In short, this method may readily provide a new family of supramolecular based materials expected to find applications beyond the bactericidal field.
Co-reporter:Jianfeng Shen, Tie Li, Weishi Huang, Yu Long, Na Li, Mingxin Ye
Electrochimica Acta 2013 Volume 95() pp:155-161
Publication Date(Web):15 April 2013
DOI:10.1016/j.electacta.2013.02.034
Co-reporter:Tie Li, Jianfeng Shen, Na Li, Mingxin Ye
Journal of Alloys and Compounds 2013 Volume 548() pp:89-95
Publication Date(Web):25 January 2013
DOI:10.1016/j.jallcom.2012.09.010
A facile and effective self-catalyzed sucrose combustion was developed to synthesize single-phase BiFeO3 (BFO) that exhibited unusual ferromagnetic properties. Microscopy techniques were employed to examine morphologies and structures of the BFO. Reaction mechanism of the formation of the BFO was deduced by using thermo-gravimetric analysis and differential scanning calorimetry. Moreover, optical properties of the BFO were investigated by using UV–vis spectroscopy. Both magnetization hysteresis loops and zero field-cooling/field-cooling indicated that BFO had typical characteristics of spin-glass. X-ray photoelectron spectroscopy was used to expose the origin of the magnetism of the sample.Graphical abstractWell single-phase multiferroic BiFeO3 was instantaneously prepared successfully by a facile and rapid strategy assisted by self-catalyzed sucrose combustion. Its structure, morphology and unusual ferromagnetic properties were investigated.Highlights► Well single-phase multiferroic BFO is instantaneously prepared successfully by this facile and low-cost process relative to other solid state way, which avoids the repeated grinding and palletizing. ► The reaction takes place under a very moderate heating at 250 °C, and the required time is very short as the whole process is completed in less than 3 min. ► The reaction mechanism is deduced by thermal analysis: a self-canalization triggers the combustion of the fuel lead to form BFO in present of metal oxides. ► The prepared single-phase BFO has optical and unusual ferromagnetic properties.
Co-reporter:Tie Li, Jianfeng Shen, Na Li, Mingxin Ye
Materials Letters 2013 Volume 91() pp:42-44
Publication Date(Web):15 January 2013
DOI:10.1016/j.matlet.2012.09.045
In this paper, we have reported a facile method for preparation of reduced graphene–BiFeO3 nanocomposite through the self-assembly decoration of BiFeO3 nanoparticles on reduced graphene via a hydrothermal process for the first time. The structure, composition and morphology characterizations of the nanocomposite indicated that pure BiFeO3 perovskite phase was successfully processed, which anchored on the surface of reduced graphene sheets and had good dispersion behavior, confirming that the technique in this paper acted as a good strategy. The magnetic and UV–vis absorption spectroscopy measurement showed that the magnetization and optical activity of the nanocomposite were found to be changed compared with those of pure BiFeO3, which would be promising for more practical applications in future nanotechnology.Graphical AbstractWe have reported a facile method for preparation of reduced graphene–BiFeO3 nanocomposite via a hydrothermal process for the first time. The magnetic and optical performances of this nanocomposite could be enhanced by the interaction between reduced graphene oxide and BiFeO3 compared with the pure BiFeO3.Highlights► Reduced graphene–BiFeO3 nanocomposite was prepared via a hydrothermal process for the first time. ► Magnetic property of the nanocomposite was increased compared with pure BiFeO3 and can be easily separated from the solution by a magnet. ► The nanocomposite could absorb not only visible light (425 nm) like the traditional pure BFO but also considerable amounts of ultraviolet light (352 nm) unusually.
Co-reporter:Wenbin Wang, Jianfeng Shen, Na Li, Mingxin Ye
Materials Letters 2013 Volume 106() pp:284-286
Publication Date(Web):1 September 2013
DOI:10.1016/j.matlet.2013.05.042
•Reduction of GO and preparation of photocatalyst RGO–ZnWO4 was simultaneous.•The prepared RGO–ZnWO4 shows high photocatalytic activity under visible light.•Ionic liquid can be utilized to control the structure of RGO–ZnWO4.•In situ growth of uniform ZnWO4 particles on RGO sheets is facile and “green”.Nanohybrid of Zinc tungstate (ZnWO4) nanoparticles and chemically reduced graphene oxide (RGO) sheets was synthesized with a “green”, ionic-liquid assisted hydrothermal process. The prepared RGO–ZnWO4s have been thoroughly characterized by spectroscopic and thermogravimetric analysis. Based on transmission electron microscopic study, RGO does not change the structure and morphology of the ZnWO4 photocatalyst, while its visible light photoactivity toward degradation of dye pollutants is greatly improved. The enhancement of photocatalytic activity is attributed to the high separation efficiency of photoinduced electron–hole pairs in RGO–ZnWO4.Nanohybrid of Zinc tungstate (ZnWO4) nanoparticles and chemically reduced graphene oxide (RGO) sheets was synthesized with an ionic-liquid assisted hydrothermal process. The improvement in the photoactivity of the RGO–ZnWO4 composite can be ascribed to RGO, which has a great effect on the degradation of dye pollutants like methyl orange and rhodamine B.
Co-reporter:Zhiqiang Li, Jianfeng Shen, Hongwei Ma, Xin Lu, Min Shi, Na Li, Mingxin Ye
Materials Science and Engineering: C 2013 Volume 33(Issue 4) pp:1951-1957
Publication Date(Web):1 May 2013
DOI:10.1016/j.msec.2013.01.004
A methodology is described for the preparation of pH- and temperature-responsive double network (DN) hydrogels with poly(N-isopropylacrylamide) (PNIPAM) as a tightly crosslinked 1st network, polyacrylic acid (PAA) as a loosely crosslinked 2nd network and graphene oxide (GO) as an additive. GO sheets were first prepared via an oxidation reaction and then dispersed in NIPAM aqueous solution via silanization. Free-radical polymerization of NIPAM was carried out at 20 °C in a water bath, and then subjected to UV light, leading to the formation of pH- and temperature-responsive PNIPAM/AA/GO DN hydrogels. The effects of GO sheets and AA contents on various physical properties were investigated. Results show that PNIPAM/AA/GO hydrogels undergo a large volumetric change in response to temperature. It also exhibits significantly fast swelling/deswelling compared with conventional PNIPAM hydrogel. Moreover, the PNIPAM/AA/GO hydrogels have a much better mechanical property than the conventional PNIPAM hydrogels.Highlights► A methodology is described for the preparation of DN hydrogels. ► The novel DN hydrogels exhibit a VPTT around 29 °C. ► The novel DN hydrogels exhibit excellent swelling/deswelling behavior. ► The novel DN hydrogels possess good mechanical properties. ► The pH sensitivity of DN hydrogels was evident below their VPTT.
Co-reporter:Jianfeng Shen, Xianfu Li, Weishi Huang, Na Li, Mingxin Ye
Materials Research Bulletin 2013 48(9) pp: 3112-3116
Publication Date(Web):
DOI:10.1016/j.materresbull.2013.04.077
Co-reporter:Xin Lu, Jianfeng Shen, Hongwei Ma, Bo Yan, Zhiqiang Li, Min Shi, Mingxin Ye
Journal of Power Sources 2012 Volume 201() pp:340-346
Publication Date(Web):1 March 2012
DOI:10.1016/j.jpowsour.2011.10.099
Metal-doped carbon xerogels (M-DCXs, M = Co, Fe, and Ni) have been obtained by a cost-effective sol–gel method using metal nitrates as catalyst, followed by solvent exchange and then dried in ambient conditions before carbonization procedure. It is found that the existence of metals could also lead to 2 dimensional (2D) channel-like nanostructure caused by layered deposits of graphite during the carbonization procedure. The performance of M-DCXs for electric double-layer capacitors is proved to be associated with their nanostructure. As a result, the as-prepared Co-DCX can make full use of the 2D channel-like nanostructure of ordered graphite and 3D connectivity of mesoporous structure of carbon xerogel, and thus, exhibits the highest capacitance of 84 F g−1. At the same time, Co-DCX also shows a stable long-term cycling behavior with less than 2% loss of capacitance after 2000 cycles.Highlights► Metal nitrates’ double roles as catalyst of sol–gel reaction and graphitization to simplify the process. ► 2 dimensional channel-like active graphitic structure helps to show a better capacitive behavior. ► Co doped carbon xerogel exhibited the largest specific capacitance of 84 F g−1 and good cycling stability.
Co-reporter:Jianfeng Shen, Tie Li, Yu Long, Min Shi, Na Li, Mingxin Ye
Carbon 2012 Volume 50(Issue 6) pp:2134-2140
Publication Date(Web):May 2012
DOI:10.1016/j.carbon.2012.01.019
We have developed an easy and scalable chemical reduction method assisted by microwave irradiation for the synthesis of reduced graphene oxide (RGO) nanosheets in solid state. The as-synthesized RGO is characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetry, X-ray diffraction, X-ray photoelectron spectroscopy and atomic force microscopy. It is revealed that the bulk of the oxygen-containing functional groups are removed from graphene oxide with this one-step reduction method and monolayer RGO sheets are got from its N,N-dimethyl formamide solution. It is found that the ammonium bicarbonate plays a key role in the preparation of RGO. Considering the analysis results, a mechanism for the formation of RGO is proposed. Besides being eco-friendly, when compared to previous chemical techniques, this process has several advantages like low cost, simplicity and short processing times, which may find practical applications in the preparation of graphene-based composites.
Co-reporter:Zhiqiang Li, Jianfeng Shen, Hongwei Ma, Xin Lu, Min Shi, Na Li and Mingxin Ye
Soft Matter 2012 vol. 8(Issue 11) pp:3139-3145
Publication Date(Web):06 Feb 2012
DOI:10.1039/C2SM07012J
A methodology is described for the preparation of pH- and temperature-responsive semi-interpenetrating hydrogels with surface-functionalized graphene oxide (GO) as the crosslinker, N-isopropylacrylamide (NIPAM) as the monomer and sodium alginate (SA) as an additive. GO sheets were first prepared via an oxidation reaction in aqueous solution and then modified with 3-(trimethoxysilyl)propylmethacrylate (TMSPMA) via a silanization reaction. Free-radical polymerization of NIPAM and SA was then carried out with the presence of TMSPMA-modified GO sheets at 20 °C in a water bath, leading to the formation of pH- and temperature-responsive PNIPAM/SA/GO hydrogels crosslinked with TMSPMA-modified GO sheets. The effects of TMSPMA-modified GO sheets content on various physical properties were investigated. Results show that PNIPAM/SA/GO hydrogels undergo a large volumetric change in response to temperature. It also exhibits significantly larger water uptake compared to conventional PNIPAM/SA hydrogels. Moreover, the PNIPAM/SA/GO hydrogels have a much better mechanical properties than the conventional PNIPAM/SA hydrogels.
Co-reporter:Jianfeng Shen, Bo Yan, Tie Li, Yu Long, Na Li and Mingxin Ye
Soft Matter 2012 vol. 8(Issue 6) pp:1831-1836
Publication Date(Web):22 Dec 2011
DOI:10.1039/C1SM06970E
Graphene oxide (GO) is added into poly(acrylic acid) (PAA) hydrogels to modify their mechanical and thermal properties. The original PAA hydrogels, which are commonly crosslinked by N,N-methylenebisacrylamide (BIS), generally exhibit pronounced weakness and brittleness. When GO was added into the BIS-gel, the GO–BIS-gels become very tough and exhibited fairly good strength. The mechanical and thermal properties of GO–BIS-gels vary greatly by changing GO or BIS content. As for the swelling behaviors of the hydrogels, they are found to be still sensitive to pH. However, the BIS-gels have a higher equilibrium swelling ratio and swell faster than that of corresponding GO–BIS-gels. In addition, the deswelling ratio decreases with the increase of GO content. The cross-linking of GO with PAA is the main factor for these phenomenon. Thus, the content of GO and BIS can be adjusted for preparing hydrogels with different properties for a wide range of applications.
Co-reporter:Jianfeng Shen, Yu Long, Tie Li, Min Shi, Na Li, Mingxin Ye
Materials Chemistry and Physics 2012 Volume 133(Issue 1) pp:480-486
Publication Date(Web):15 March 2012
DOI:10.1016/j.matchemphys.2012.01.069
We demonstrated a facile and efficient strategy for the fabrication of poly(diallyldimethylammonium chloride) (PDDA)-assisted reduced graphene oxide (RGO) sheets–titanium dioxide (TiO2) in the absence of any seeds and surfactants. PDDA is used as both a reducing agent and a stabilizer to prepare the colloidal suspension of graphene nanosheets. The incorporation of PDDA successfully turns graphene nanosheets into general platforms for in situ growth of TiO2. The prepared TiO2–RGO has been thoroughly characterized by spectroscopic (Fourier-transform infrared spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy) and thermogravimetric analysis. Microscopy techniques (scanning electron microscopy, atomic force microscopy and transmission electron microscopy) have been employed to probe the morphological structures as well as to investigate the exfoliation of RGO sheets. It is interesting to see that the TiO2–RGO composites exhibited excellent photocatalytic activity to hydrogen evolution.Highlights► PDDA is used as both a reducing agent and a stabilizer to prepare RGO nanosheets. ► Incorporation of PDDA turns RGO nanosheets into platforms for in situ growth of TiO2. ► The prepared TiO2–RGO shows very high photocatalytic activity.
Co-reporter:Tie Li, Jianfeng Shen, Na Li, Mingxin Ye
Materials Letters 2012 Volume 89() pp:202-205
Publication Date(Web):15 December 2012
DOI:10.1016/j.matlet.2012.08.132
We report for the first time a facile and efficient strategy to prepare carbon microspheres by the polymerization of glucose in the presence of graphene under hydrothermal carbonization. The morphologies characterizations of the as-synthesized products confirmed that the technique in this paper acted as a good strategy. A great deal of carbon microspheres with good morphology and uniform diameter were prepared. The structure characterizations indicated that there were many functional groups on the surface while the spheres were mostly amorphous structure. A formation mechanism was proposed that involved curved graphene sheets as a substrate for microsphere formation. As this route is low-cost, green and simple, and the experimental parameters are very easy to control, it may provide a great convenience to study properties and applications of carbon microspheres.Graphical abstractFunctionalised carbon microspheres with well-morphology and uniform diameter were the first time synthesized by a facile, efficient and green strategy, using a hydrothermal carbonization from glucose solution assisted by graphene sheets as a substrate.Highlights► Graphene sheets were first used to synthesize carbon microspheres as a substrate. ► The preparation method was a noble, low-cost, facile and utterly ‘green’ strategy. ► The amorphous carbon spheres were functionalised microspheres. ► A conformational three-state mechanism for the process of carbon microspheres has been proposed.
Co-reporter:Jianfeng Shen, Bo Yan, Min Shi, Hongwei Ma, Na Li, Mingxin Ye
Materials Research Bulletin 2012 47(6) pp: 1486-1493
Publication Date(Web):
DOI:10.1016/j.materresbull.2012.02.025
Co-reporter:Jianfeng Shen, Tie Li, Min Shi, Na Li, Mingxin Ye
Materials Science and Engineering: C 2012 Volume 32(Issue 7) pp:2042-2047
Publication Date(Web):1 October 2012
DOI:10.1016/j.msec.2012.05.017
We demonstrate an effective one-pot hydrothermal route for the synthesis of Poly (diallyldimethylammonium chloride) (PDDA)-protected reduced graphene oxide (RGO) sheets-silver (Ag) nanocomposite in the absence of any seeds and surfactants. In this method, PDDA, an ordinary and water-soluble polyelectrolyte, acts as both a reducing and a stabilizing agent. More importantly, the incorporation of PDDA as a “glue” molecule successfully turns RGO into general platforms for in situ growth of Ag. Small Ag nanoparticles with average height of 4 nm are distributed on the surface of RGO sheets. It is also found that the antibacterial activity of Ag nanoparticles is retained in the composite, suggesting that it can be used as RGO-based biomaterial.Highlights► Polyelectrolyte-assisted hydrothermal synthesis of Ag–RGO composite was achieved. ► Polyelectrolyte acts as both a reducing and a stabilizing agent. ► The reduction of graphene oxide and synthesizing of Ag–RGO was simultaneous. ► The antibacterial activity of Ag nanoparticles is retained in the composite.
Co-reporter:Zhiqiang Li;Jianfeng Shen;Hongwei Ma;Xin Lu;Min Shi;Na Li
Polymer Bulletin 2012 Volume 68( Issue 4) pp:1153-1169
Publication Date(Web):2012/03/01
DOI:10.1007/s00289-011-0671-0
pH- and temperature-responsive semi-interpenetrating magnetic nanocomposite hydrogels (NC hydrogels) were prepared by using linear sodium alginate (SA), poly(N-isopropylacrylamide) (PNIPAM) and Fe3O4 nanoparticles with inorganic clay as an effective multifunctional cross-linker. The effects of cross-linker and SA contents on various physical properties were investigated. The NC hydrogels exhibited a volume phase transition temperature (VPTT) around 32 °C with no significant deviation from the conventional chemically cross-linked PNIPAM hydrogels (OR hydrogels). The swelling ratios of NC hydrogels were much larger than those of OR hydrogels. Moreover, the swelling ratios of NC hydrogels gradually decreased with increasing the contents of clay and increased with increasing the contents of SA. The pH sensitivity of NC hydrogels was evident below their VPTT. The NC hydrogels had a much better mechanical property than the OR hydrogels. The results showed that the incorporation of clay did not affect the saturation magnetization of the hydrogels.
Co-reporter:Min Shi, Jianfeng Shen, Hongwei Ma, Zhiqiang Li, Xin Lu, Na Li, Mingxin Ye
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2012 Volume 405() pp:30-37
Publication Date(Web):5 July 2012
DOI:10.1016/j.colsurfa.2012.04.031
In this paper, an environmentally friendly and efficient strategy for the preparation of titanium oxide (TiO2) nanoparticles–reduced graphene oxide (RGO) composite with hydrothermal process was demonstrated. First, we reduced graphene oxide to RGO by using dextran as reducing agent and surface modifier. Then the TiO2 nanoparticles were successfully prepared from a water soluble precursor, peroxotitanium acid and attached to dextran–RGO nanosheets due to hydrogen bond and van der Waals interactions. The structure and composition of the nanocomposite has been characterized by UV–vis absorption spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermal gravimetric analysis, Raman spectroscopy, X-ray diffraction and atomic force microscopy. The photodegradation and photoelectrochemical measurement results indicated that the as-prepared TiO2/RGO composite had an excellent photocatalytic activity, which would be promising for practical application in future nanotechnology.Graphical abstractHighlights► Peroxotitanium acid as titanium precursor. ► No toxic organic solvent was used. ► Colloidal suspensions of high TiO2 loading amount nanocomposite was prepared. ► As-prepared composite showed better photocatalytic activity.
Co-reporter:Jianfeng Shen, Min Shi, Bo Yan, Hongwei Ma, Na Li and Mingxin Ye
Journal of Materials Chemistry A 2011 vol. 21(Issue 21) pp:7795-7801
Publication Date(Web):19 Apr 2011
DOI:10.1039/C1JM10671F
A one-pot hydrothermal reaction was used to prepare a reduced graphene oxide sheets (RGO)-silver (Ag) nanoparticles composite using graphite oxide and silver nitrate as starting materials. It was found that graphene oxide could be well reduced under the hydrothermal conditions with ascorbic acid as the reductant, while the Ag nanoparticles were grown on the RGO surface simultaneously. The reduction of graphene oxide and synthesizing of Ag-RGO were confirmed by Fourier-transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, X-ray diffraction and X-ray photoelectron spectroscopy. Microscopy techniques (scanning electron microscopy, atomic force microscopy and transmission electron microscopy) have been employed to probe the morphological characteristics as well as to investigate the exfoliation of RGO sheets. The intensities of the Raman signals of RGO in the composite are greatly increased by the attached Ag nanoparticles, showing surface-enhanced Raman scattering activity. Besides, it was found that the antibacterial activity of free Ag nanoparticles is retained in the composite, suggesting that it can be used as RGO-based biomaterials.
Co-reporter:Jianfeng Shen, Bo Yan, Min Shi, Hongwei Ma, Na Li and Mingxin Ye
Journal of Materials Chemistry A 2011 vol. 21(Issue 10) pp:3415-3421
Publication Date(Web):04 Jan 2011
DOI:10.1039/C0JM03542D
We demonstrated an environmentally friendly and efficient route for the preparation of titanium oxide (TiO2) nanoparticles-reduced graphene oxide composite with a one-step hydrothermal method using glucose as the reducing agent. The reducing process was accompanied by generation of TiO2 nanoparticles. The structure and composition of the nanocomposite has been characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, thermal gravimetric analysis and atomic force microscopy. The TiO2-coated RGO nanocomposite was shown to improve the photocatalytic property of TiO2, which would be promising for practical applications in future nanotechnology.
Co-reporter:Jianfeng Shen, Bo Yan, Min Shi, Hongwei Ma, Na Li, Mingxin Ye
Journal of Colloid and Interface Science 2011 Volume 356(Issue 2) pp:543-549
Publication Date(Web):15 April 2011
DOI:10.1016/j.jcis.2011.01.052
In this work, a novel and facile method for covalent attachment of biomaterials to graphene oxide sheets (GOS) was developed. Four conjugates were obtained via the diimide-activated amidation reaction under ambient conditions. Final products were characterized by FT-IR spectroscopy, atomic force microscopy and transmission electron microscopy. Electrochemical characterization of the composite showed that the covalently bonded biomaterial retained its bioactivity. This method may provide a way for further preparation of graphene-based biodevices.Graphical abstractA novel and facile method for attachment of biomaterials to graphene oxide sheets was developed. The covalently bonded biomaterial retained its bioactivity.Research highlights► Diimide-activated amidation was used to attach biomaterials to graphene oxide sheets. ► It causes no denaturing of the biomaterials and guaranties the uniform attachment. ► The same method can be used to introduce GOS into other biosystems.
Co-reporter:Jianfeng Shen;Min Shi;Bo Yan;Hongwei Ma;Na Li
Nano Research 2011 Volume 4( Issue 8) pp:
Publication Date(Web):2011 August
DOI:10.1007/s12274-011-0136-7
Co-reporter:Jianfeng Shen, Min Shi, Hongwei Ma, Bo Yan, Na Li, Mingxin Ye
Materials Research Bulletin 2011 46(11) pp: 2077-2083
Publication Date(Web):
DOI:10.1016/j.materresbull.2011.06.042
Co-reporter:Hongwei Ma, Jianfeng Shen, Min Shi, Bo Yan, Na Li, Mingxin Ye
Materials Research Bulletin 2011 46(9) pp: 1461-1466
Publication Date(Web):
DOI:10.1016/j.materresbull.2011.05.003
Co-reporter:Jianfeng Shen, Na Li, Min Shi, Yizhe Hu, Mingxin Ye
Journal of Colloid and Interface Science 2010 Volume 348(Issue 2) pp:377-383
Publication Date(Web):15 August 2010
DOI:10.1016/j.jcis.2010.04.055
In this study, we report a scalable, fast, and easy method for preparation of organophilic chemically functionalized graphene (OCFG) sheets. The basic strategy involved the preparation of graphite oxide (GO) and the complete exfoliation of GO into graphene oxide sheets, followed by reacting with 1-bromobutane to obtain OCFG sheets. Thermogravimetric analysis, Raman spectroscopy, and Fourier transform infrared spectroscopy indicated the functionalization of GO. Transmission electron microscopy and atomic force microscopy were used to demonstrate the structure of produced graphene oxide and OCFG sheets. Ultraviolet–visible spectroscopy confirmed that OCFG sheets disperse well in organic solvents and the solutions obey Beer’s law. The resulting organic dispersions are homogeneous, exhibit long-term stability, and are made up of graphene sheets a few hundred nanometers large. The ability to prepare graphene dispersions in organic media facilitates their combination with polymers to yield homogeneous composites.Organophilic chemically functionalized graphene was prepared by reacting 1-bromobutane with graphene oxide and the resulting homogeneous organic media exhibits long-term stability.
Co-reporter:Jianfeng Shen;Chen Qin;Yizhe Hu;Na Li
Polymer Composites 2010 Volume 31( Issue 12) pp:2035-2041
Publication Date(Web):
DOI:10.1002/pc.21001
Abstract
Magnetic single-walled carbon nanotubes (SWCNTs) were synthesized in a process consisting of two steps: (a) covalent in situ polymerization and grafting of poly (acrylic acid) (PAA) on the surface of SWCNTs, followed by (b) thermal decomposition of ferric triacetylacetonateto produce magnetite nanoparticles on the PAA-grafted SWCNTs. It was demonstrated that magnetic nanoparticle–coated SWCNTs dispersed in water by sonication would respond to an external magnetic field. On such functionalization, the reorientation of SWCNTs in an epoxy matrix could be produced using a magnet. This endowed the composites with desirable magnetic and mechanical properties. POLYM. COMPOS., 31:2035–2041, 2010. © 2010 Society of Plastics Engineers
Co-reporter:Yizhe Hu;Jianfeng Shen;Na Li;Min Shi;Hongwei Ma;Bo Yan;Wenbin Wang;Weishi Huang
Polymer Composites 2010 Volume 31( Issue 12) pp:1987-1994
Publication Date(Web):
DOI:10.1002/pc.20984
Abstract
Expandable graphite oxide (EGO) was functionalized with different amine groups after sequential steps as thermal expansion, oxidation, acylation, and amidation. Three types of amino-functionalized graphenes (a-Gphs) were prepared by exfoliating amino functionalized EGOs(a-EGO) through controlled ultrasonication. Fourier transform infrared spectroscopy, elementary analysis, X-ray diffraction, and thermogravimetric analysis separately confirmed the chemical structure of a-EGO. The effect of ultrasonic power on the particle sizes of exfoliated a-EGOs was estimated by dynamic light scattering. Single layered graphene (0.43 nm) was achieved after ultrasonicating at 500 W for 20 min, which was affirmed by the results of atomic force microscopy and transmission electron microscopy. Ultra violet–visible spectroscopy also indicates the good dispersion properties of a-Gphs in these solvents. The thermal properties of composites are obviously increased by adding a-Gphs and a-EGOs as nanofillers. POLYM. COMPOS., 2010. © 2010 Society of Plastics Engineers
Co-reporter:Jianfeng Shen, Min Shi, Bo Yan, Hongwei Ma, Na Li, Yizhe Hu, Mingxin Ye
Colloids and Surfaces B: Biointerfaces 2010 Volume 81(Issue 2) pp:434-438
Publication Date(Web):1 December 2010
DOI:10.1016/j.colsurfb.2010.07.035
In this paper, graphene oxide nanosheets (GOS) are functionalized by bovine serum albumin (BSA) via diimide-activated amidation under ambient conditions. The obtained GOS–BSA conjugate is highly water-soluble. Results of atomic force microscopy (AFM), Raman spectra and Fourier transform infrared spectroscopy analysis confirm that GOS–BSA conjugate contains both GOS and BSA protein. AFM image shows that GOS are fully exfoliated. Results of cyclic volatammograms show that the protein in the GOS–BSA conjugate retains its bioactivity. The present method may also provide a way to synthesize graphene-based composites with other biomolecules.Graphene oxide nanosheets (GOS) are functionalized by bovine serum albumin (BSA) via diimide-activated amidation under ambient conditions and the obtained GOS–BSA conjugate is highly water-soluble.
Co-reporter:Jianfeng Shen, Yizhe Hu, Min Shi, Na Li, Hongwei Ma and Mingxin Ye
The Journal of Physical Chemistry C 2010 Volume 114(Issue 3) pp:1498-1503
Publication Date(Web):January 4, 2010
DOI:10.1021/jp909756r
In this study, graphene oxide−magnetic nanoparticle composites were prepared by attaching magnetic nanoparticles to graphene oxide through a high temperature reaction of ferric triacetylacetonate with graphene oxide in 1-methyl-2-pyrrolidone. X-ray diffraction, transmission electron morphology, and thermogravimetric analysis were used to demonstrate the successful attachment of iron oxide nanoparticles to graphene sheets. It was found that the attached nanoparticles were mainly magnetite. Investigations using Fourier transform infrared spectroscopy proved that the tight attachment was due to the robust linkage: metal−carbonyl coordination.
Co-reporter:Jianfeng Shen;Min Shi;Na Li;Bo Yan;Hongwei Ma;Yizhe Hu
Nano Research 2010 Volume 3( Issue 5) pp:339-349
Publication Date(Web):2010 May
DOI:10.1007/s12274-010-1037-x
Co-reporter:Jianfeng Shen, Yizhe Hu, Min Shi, Xin Lu, Chen Qin, Chen Li and Mingxin Ye
Chemistry of Materials 2009 Volume 21(Issue 15) pp:3514
Publication Date(Web):July 15, 2009
DOI:10.1021/cm901247t
In this study, we report an inexpensive, massively scalable, fast, and facile method for preparation of graphene oxide and reduced graphene oxide nanoplatelets. The basic strategy involved the preparation of graphite oxide (GO) from graphite through reaction with benzoyl peroxide (BPO), complete exfoliation of GO into graphene oxide sheets, followed by their in situ reduction to reduced graphene oxide nanoplatelets. The mechanism of graphene oxide producing is mainly the generation of oxygen-containing groups on graphene sheets. In addition, inserted BPO and expansion of CO2 evolved during reaction will expand the distance between graphite layers, which are also main factors for exfoliation. Thermogravimetric analysis, Raman spectroscopy, and Fourier transform infrared spectroscopy indicated the successful preparation of GO. X-ray diffraction proved the mechanism of intercalation and exfoliation of graphite. Transmission electron microscopy and atomic force microscopy were used to demonstrate the structure of produced graphene oxide and reduced graphene oxide nanoplatelets.
Co-reporter:Yizhe Hu;Jianfeng Shen;Chen Qin;Liping Wu;Binbin Zhang
Polymer Composites 2009 Volume 30( Issue 4) pp:374-380
Publication Date(Web):
DOI:10.1002/pc.20563
Abstract
The 1,6-hexanediamine-functionalized multi-walled carbon nanotubes(a-MWNTs)/polyimide(PI) nanocomposite films were prepared through in-situ polymerization followed by mixture casting, evaporation, and thermal imidization. To increase the compatibility of carbon nanotubes with the matrix polyimide, a-MWNTs was used as the filler. According to the results, a-MWNTs were homogeneously dispersed in the nanocomposite films. With the incorporation of a-MWNTs, the mechanical properties of the resultant films were improved due to the strong chemical bonding and interfacial interaction between a-MWNTs and 4,4′-oxydiphthalic anhydride(ODPA)/4,4′-Oxydianiline(ODA) polyimide matrix. The thermal stability of the a-MWNTs/polyimide nanocomposite was also improved by the addition of a-MWNTs. The electrical tests showed a percolation threshold at about 0.85 vol% and the electrical properties were increased sharply. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Co-reporter:Chen Li;Chen Qin;Jianfeng Shen;Yizhe Hu
Journal of Sol-Gel Science and Technology 2009 Volume 50( Issue 1) pp:8-14
Publication Date(Web):2009/04/01
DOI:10.1007/s10971-009-1916-3
We prepared lithiated borate (LB) during sol–gel process and found that it could greatly lower the degradation temperature (Td) of Polystyrene (PS). The lithium insertion process was carried out in the same time as tributyl borate hydrolysis in the water. The crystal structure of LB is identified via X-ray diffraction (XRD). The XRD results show that the particle is boric acid. Raman spectroscopy reveals that intercalation Li+ ion can be coordinated with O. The structure of LB xerogel in this experiment is mainly determined by the ratio of ethanol to water, amount of lithium and acid or alkali circumstances during sol–gel process, which in turn determines the lithium reactivity to the degradation of PS. The investigation of polystyrene degradation temperature with LB xerogel indirectly proved the coordination state of Li+ in LB xerogel, which was also confirmed by Raman.
Co-reporter:Jianfeng Shen, Yizhe Hu, Chen Li, Chen Qin, Min Shi and Mingxin Ye
Langmuir 2009 Volume 25(Issue 11) pp:6122-6128
Publication Date(Web):March 10, 2009
DOI:10.1021/la900126g
In this report, graphene nanoplatelets were self-assembled through the layer-by-layer (LBL) method. The graphene surface was modified with poly(acrylic acid) and poly(acryl amide) by covalent bonding, which introduced negative and positive charge on the surface of graphene, respectively. Through electrostatic interaction, the positively and negatively charged graphene nanoplatelets assembled together to form a multilayer structure. Thermogravimetric analysis, Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy were used to demonstrate the modification of graphene nanoplatelets. Fourier transform infrared spectroscopy and SEM proved this method is feasible for preparing graphene-containing films. Ultraviolet−visible spectroscopy confirmed that the adsorption technique resulted in uniform film growth.
Co-reporter:Chen Qin, Chen Li, Yizhe Hu, Jianfeng Shen, Mingxin Ye
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2009 Volume 336(1–3) pp:130-134
Publication Date(Web):20 March 2009
DOI:10.1016/j.colsurfa.2008.11.040
Magnetic nanoparticles were generated by thermal decomposition of ferric triacetylacetonate in the presence of 1-methyl-2-pyrrolidone, a functional solvent. The particle size and shape could be varied by altering reaction parameters. For example, with the addition of oleic acid surfactant, smaller particles were produced. In addition, step elevation of reaction temperature was in favor of regular particle morphology. The obtained iron oxide nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis and vibrating sample magnetometer. All of the experimental evidences supported that we succeeded in synthesizing monodisperse iron oxide nanoparticles via a facile and effective route. Moreover, when the oleic acid was added, 1-methyl-2-pyrrolidone and oleic acid possibly forms an intercalated monolayer on the particle surface.
Co-reporter:Jianfeng Shen, Yizhe Hu, Chen Li, Chen Qin, Mingxin Ye
Electrochimica Acta 2008 Volume 53(Issue 24) pp:7276-7280
Publication Date(Web):15 October 2008
DOI:10.1016/j.electacta.2008.04.019
Catalyst of Pt–Co supported on single-walled carbon nanotubes (SWCNTs) is prepared using mixed reducing agents. The SWCNTs were pretreated in a microwave oven to enable surface modification. Pt–Co nanoparticles with narrow particle size distribution around 5.4 nm were uniformly deposited onto the SWCNTs. Under same Pt loading mass and experimental conditions, the SWCNTs–Pt–Co catalyst shows higher electrocatalytic activity and improved resistance to CO poisoning than the SWCNTs–Pt catalyst.
Co-reporter:Yizhe Hu;Liping Wu;Jianfeng Shen ;Mingxing Ye
Journal of Applied Polymer Science 2008 Volume 110( Issue 2) pp:701-705
Publication Date(Web):
DOI:10.1002/app.28644
Abstract
For the preparation of high-quality polymeric carbon nanocomposites, it is required that carbon nanotubes are fully compatible with matrix polymers. For this purpose, amino-functionalized multiple-walled carbon nanotubes (a-MWNTs) were synthesized. The a-MWNTs/polyimide nanocomposite films were prepared through in situ polymerization. According to the spectroscopic characterizations, the a-MWNTs were homogeneously dispersed in the nanocomposite films as the acid-functionalized MWNTs. The mechanical properties of the polyimide composite were also studied. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Chen Qin;Jianfeng Shen;Yizhe Hu;Weishi Huang
Polymer Engineering & Science 2008 Volume 48( Issue 3) pp:556-563
Publication Date(Web):
DOI:10.1002/pen.20966
Abstract
Thermosetting polymer blends of novolac epoxy resin (EPN) and polyethylene glycol (PEG) were studied. The miscibility and crystallization behavior of the blends before curing reaction were investigated by polarized optical microscopy and differential scanning calorimetry (DSC). Overall uncured blend compositions were homogeneous in amorphous state. Single composition-dependent glass-transition temperature (Tg) for each blend could be observed, and the experimental Tg's of blends with EPN content ≥40 wt% could be explained well by the Gordon–Taylor equation. Thermal properties of blends cured with 4,4′-diaminodiphenylmethane were also determined by DSC. The capability of PEG to crystallize in cured blends was different from that in uncured ones because of the topological effect of highly crosslinking structure. On the basis of Fourier transform infrared spectroscopy results, it was judged that there were intermolecular hydrogen-bonding interactions between EPN and PEG in both cured and uncured blends. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Co-reporter:Jianfeng Shen, Weishi Huang, Liping Wu, Yizhe Hu, Mingxin Ye
Materials Science and Engineering: A 2007 Volume 464(1–2) pp:151-156
Publication Date(Web):25 August 2007
DOI:10.1016/j.msea.2007.02.091
Functionalization with amine groups of MWNTs was achieved after such steps as carboxylation, acylation and amidation. XRD, Raman, FTIR, XPS, scanning electron microscopy (SEM) were used to investigate and determine the chemical structure and texture of the amino-functionalized MWNTs. By comparing with each other, it was found that the amino-functionalized MWNTs can improve their dispersion in H2O. However, concerning the results of XPS, SEM and dispersity analyses, other reactions may also have occurred, which influenced their dispersity in organic solvents.
Co-reporter:Guoxin Bai;Lina Chen;Liping Wu
Frontiers of Chemistry in China 2007 Volume 2( Issue 3) pp:274-277
Publication Date(Web):2007 July
DOI:10.1007/s11458-007-0049-x
A novel compound of butyl crystal violet lactone (BCVL) has been prepared by oxidizing leuco butyl crystal violet lactone (LBCVL), which was obtained by the mixture of N,N-dibutylaniline, p-(dibutylamino) benzaldehyde and methyl-m-(dibutylamino) benzoate. The structure of BCVL was characterized by 1H-nuclear magnetic resonance (NMR), infrared (IR), and mass spectrometry (MS). The color of BCVL can change reversibly in some acid or alkali solvents. The result of the dissolution experiment showed that solubility of BCVL in organic solvent was improved compared with crystal violet lactone (CVL).
Co-reporter:Tie Li, Jianfeng Shen, Shutong Huang, Na Li, Mingxin Ye
Applied Clay Science (May 2014) Volumes 93–94() pp:48-55
Publication Date(Web):May 2014
DOI:10.1016/j.clay.2014.02.015
Co-reporter:Jianfeng Shen, Na Li, Mingxin Ye
Applied Clay Science (January 2015) Volume 103() pp:40-45
Publication Date(Web):January 2015
DOI:10.1016/j.clay.2014.11.006
Co-reporter:Yinle Li, Zhuqing Zhang, Liyuan Pei, Xiaoguang Li, Tao Fan, Jin Ji, Jianfeng Shen, Mingxin Ye
Applied Catalysis B: Environmental (5 August 2016) Volume 190() pp:1-11
Publication Date(Web):5 August 2016
DOI:10.1016/j.apcatb.2016.02.054
Co-reporter:Wenzhi Fu, Zhuqing Zhang, Peiyuan Zhuang, Jianfeng Shen, Mingxin Ye
Journal of Colloid and Interface Science (1 July 2017) Volume 497() pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.jcis.2017.02.063
A facile, green, economical approach was designed to deposit palladium nanoparticles on magnetic reduced graphene oxide nanosheets (Pd-Fe3O4/rGO) via a one-pot hydrothermal synthesis method. The prepared Pd-Fe3O4/rGO nanocomposites were thoroughly characterized by Transmission electron microscopy, Scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and Raman spectroscopy. Importantly, the highly efficient catalytic property of the as-obtained Pd-Fe3O4/rGO catalyst was demonstrated for the Suzuki-Miyaura coupling reaction and Mizoroki-Heck coupling reaction. Significantly, the Suzuki-Miyaura coupling reactions could be efficiently performed in an environmentally friendly aqueous solution with no need for further additives. Besides, the nanocomposites could be conveniently separated from reaction system with an external permanent magnet for recycling and the inherent catalytic activity of the nanocomposites did not exacerbate after six repeated applications.
Co-reporter:Zheng Cui, Yuancai Ge, Hang Chu, Robert Baines, Pei Dong, Jianhua Tang, Yang Yang, Pulickel M. Ajayan, Mingxin Ye and Jianfeng Shen
Journal of Materials Chemistry A 2017 - vol. 5(Issue 4) pp:NaN1602-1602
Publication Date(Web):2016/12/02
DOI:10.1039/C6TA09853C
Fabrication of stable, efficient, and inexpensive bifunctional electro-catalysts for water splitting has become increasingly attractive. Herein, for the first time, the direct growth of Mo-doped Ni3S2 on Ni foams using sodium molybdate as the Mo source at different temperatures is demonstrated. Effects of temperature on the morphology and water splitting performance of Mo-doped Ni3S2 were discussed in detail. It is found that the atomic stoichiometric ratios of Mo and Ni can be controlled by the adjusting of reaction temperature, while the obtained electro-catalysts demonstrate various morphologies, capacitances and chemisorption free energies of hydrogen, which lead to different current densities and hydrogen evolution efficiencies. The electro-catalyst synthesized at 200 °C (200-SMN/NF) demonstrates the best regular morphology and electrochemical properties. When employed in oxygen evolution reactions, 200-SMN/NF demonstrates a low over-potential of 180 mV at 100 mA cm−2. Adapting it as a bifunctional electro-catalyst, a current density of 10 mA cm−2 at a very low cell voltage of 1.53 V and cycling lifespan of more than 15 h was delivered. Further results indicated elevated hydrogen evolution reaction activity, consisting of a moderate 278 mV over-potential at a 100 mA cm−2 hydrogen production current density, a small 72.9 mV dec−1 Tafel slope, and a superior current density compared to that of precious catalyst Pt/C (40%) after −0.53 V. These results underscore the fact that 200-SMN/NF is a high-performance, precious-metal-free electro-catalyst, and provide the foundation for exciting opportunities in water splitting applications.
Co-reporter:Jianfeng Shen, Min Shi, Bo Yan, Hongwei Ma, Na Li and Mingxin Ye
Journal of Materials Chemistry A 2011 - vol. 21(Issue 21) pp:NaN7801-7801
Publication Date(Web):2011/04/19
DOI:10.1039/C1JM10671F
A one-pot hydrothermal reaction was used to prepare a reduced graphene oxide sheets (RGO)-silver (Ag) nanoparticles composite using graphite oxide and silver nitrate as starting materials. It was found that graphene oxide could be well reduced under the hydrothermal conditions with ascorbic acid as the reductant, while the Ag nanoparticles were grown on the RGO surface simultaneously. The reduction of graphene oxide and synthesizing of Ag-RGO were confirmed by Fourier-transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, X-ray diffraction and X-ray photoelectron spectroscopy. Microscopy techniques (scanning electron microscopy, atomic force microscopy and transmission electron microscopy) have been employed to probe the morphological characteristics as well as to investigate the exfoliation of RGO sheets. The intensities of the Raman signals of RGO in the composite are greatly increased by the attached Ag nanoparticles, showing surface-enhanced Raman scattering activity. Besides, it was found that the antibacterial activity of free Ag nanoparticles is retained in the composite, suggesting that it can be used as RGO-based biomaterials.
Co-reporter:Jianfeng Shen, Jin Ji, Pei Dong, Robert Baines, Zhuqing Zhang, Pulickel M. Ajayan and Mingxin Ye
Journal of Materials Chemistry A 2016 - vol. 4(Issue 22) pp:NaN8850-8850
Publication Date(Web):2016/05/09
DOI:10.1039/C6TA03111K
Ternary electrode materials based on graphene, FeNi2S4, and transition metal dichalcogenides (TMDs) were obtained via a one-pot synthesis method. Compared to binary materials, FeNi2S4–graphene (g)–2D-TMD nanocomposites exhibited better performance, which is a direct consequence of their unique ternary structures and the induced synergistic effect among their three components—ultrathin TMD nanosheets, highly conductive graphene networks, and FeNi2S4 nanoparticles. With the fabricated materials, we constructed electrodes to assess the electrochemical performance. The results are promising: the materials exhibited rapid electron and ion transport rates and large electroactive surface areas, testifying to their excellent electrochemical properties. In particular, the FeNi2S4–g–MoSe2 electrode demonstrated a maximum specific capacitance of 1700 F g−1 at a current density of 2 A g−1 (8.5 F cm−2 at a current density of 10 mA cm−2) and a capacitance retention of approximately 106% after 4000 cycles at a charge–discharge current density of 2 A g−1. These electrochemical results indicate that the ternary composite, FeNi2S4–g–MoSe2, is a promising candidate electrode material for high-performance supercapacitors.
Co-reporter:Jianfeng Shen, Pei Dong, Robert Baines, Xiaowei Xu, Zhuqing Zhang, Pulickel M. Ajayan and Mingxin Ye
Chemical Communications 2016 - vol. 52(Issue 59) pp:NaN9254-9254
Publication Date(Web):2016/06/17
DOI:10.1039/C6CC03699F
Novel ternary electrode materials based on graphene, NiCo2S4, and transition metal dichalcogenides (TMDs) were designed and fabricated with the intention of exploiting synergistic effects conducive to supercapacitive energy storage. Compared to NiCo2S4-g-MoSe2, the NiCo2S4-g-MoS2 electrode exhibited higher specific capacitance, enhanced rate capability (1002 F g−1 even at 5 A g−1, 6.01 F cm−2 at a current density of 25 mA cm−2) and cycling stability (94.8% retention of its original capacity after cycling 4000 times). The mechanism was proposed and this pioneering work will be helpful in making judicious choices of which 2D materials to be selected for supercapacitor applications in the future.
Co-reporter:Jianfeng Shen, Bo Yan, Min Shi, Hongwei Ma, Na Li and Mingxin Ye
Journal of Materials Chemistry A 2011 - vol. 21(Issue 10) pp:NaN3421-3421
Publication Date(Web):2011/01/04
DOI:10.1039/C0JM03542D
We demonstrated an environmentally friendly and efficient route for the preparation of titanium oxide (TiO2) nanoparticles-reduced graphene oxide composite with a one-step hydrothermal method using glucose as the reducing agent. The reducing process was accompanied by generation of TiO2 nanoparticles. The structure and composition of the nanocomposite has been characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, thermal gravimetric analysis and atomic force microscopy. The TiO2-coated RGO nanocomposite was shown to improve the photocatalytic property of TiO2, which would be promising for practical applications in future nanotechnology.
Co-reporter:Jianhua Tang, Yuancai Ge, Jianfeng Shen and Mingxin Ye
Chemical Communications 2016 - vol. 52(Issue 7) pp:NaN1512-1512
Publication Date(Web):2015/11/25
DOI:10.1039/C5CC09402J
CuCo2S4 nanoparticles demonstrating outstanding electrochemical performances were firstly synthesized through a simple solvothermal approach without using any templates. CuCo2S4 synthesized in glycerol (CuCo2S4–glycerol) fulfills an ultrahigh capacitance of 5030 F g−1 at 20 A g−1 in a polysulfide electrolyte.
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