Co-reporter:Guangfan Zheng, Jiaqiong Sun, Yang Liu, Shengbiao Yang, Yan Li, Haizhu Sun, and Qian Zhang
The Journal of Organic Chemistry December 1, 2017 Volume 82(Issue 23) pp:12813-12813
Publication Date(Web):October 27, 2017
DOI:10.1021/acs.joc.7b02148
A facile and efficient copper-catalyzed azidative multifunctionalization of alkynes has been developed by using N-fluorobenzenesulfonimide (NFSI) as both nitrogen source and aryl source and trimethylsilyl azide (TMSN3) as azido source. This transformation proceeds under mild conditions, providing a series of α-azido-α-aryl imine in good yields by a single operation starting from a wide range of alkynes. The prepared α-azido-α-aryl imines could be easily converted into 1,5-piperizine-fused 1,2,3-triazoles and azido enamines.
Co-reporter:Hai-Feng Wang, Chao-Ying Fan, Xiao-Ying Li, Xing-Long Wu, Huan-Huan Li, Hai-Zhu Sun, Hai-Ming Xie, Jing-Ping Zhang, Cui-Yan Tong
Electrochimica Acta 2017 Volume 244(Volume 244) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.electacta.2017.05.090
Lithium sulfur (Li-S) batteries possess high theoretical specific capacity (1675 mAh g−1) and energy density (2567 Wh kg−1), but are plagued by their poor rate performance. The discovery of new carbon sources, design of novel porous carbon structures, and effective hetero-atom doping of the sulfur matrix are key to overcome this dilemma. In this paper, a boron-doped porous carbon material with a termite nest shape (TNPBC) was obtained from a new carbon source, polyaspartic acid, and borax. Importantly, the doping, activation, and pyrolysis were integrated into one step through a low cost and simple methodology. The borax was essential to formation of a high surface porous architecture and provided boron dopants, which, combined with polyaspartic acid, achieves co-doping (B and N) carbon materials with special porous structures. The simultaneous pore-formation and doping leave an abundance of hetero-atoms exposed on the surface of pores, which enhances the electrostatic interactions between the hetero-atoms and the charged species in the batteries. As a result, the S/TNPBC cathode maintains a stable capacity of 703 mAh g−1 with an excellent Coulombic efficiency of 101.3% after 120 cycles at 0.1C. Moreover, it exhibits an excellent rate capability with an initial capacity of 650 mAh g−1 at 0.5C and sustains a capacity of 500 mAh g−1 after 100 cycles. Furthermore, when TNPBC is used as the anode in a sodium ion battery, an excellent rate capability is achieved. The specific charge capacity is three times greater than without boron doping at 500 mA g−1. Due to the simple fabrication process and desirable properties of this novel architecture, TNPBC provides a new strategy for enhancing the performance of commercial energy storage devices.A novel kind of porous boron-doped carbon (TNPBC) with a termite nest structure was synthesized by combining doping, activation, and pyrolysis into one step. Using the synthesized material as a sulfur reservoir, TNPBC effectively relieved the “shuttle effect” commonly found in Li-S electrodes and achieved a decent rate performance in Li-S and sodium ion batteries.Download high-res image (181KB)Download full-size image
Co-reporter:Huan-Huan Li, Lei Zhou, Lin-Lin Zhang, Chao-Ying Fan, Hong-Hong Fan, Xing-Long WuHai-Zhu Sun, Jing-Ping Zhang
ACS Energy Letters - New in 2016 2017 Volume 2(Issue 1) pp:
Publication Date(Web):December 1, 2016
DOI:10.1021/acsenergylett.6b00564
Herein, we develop a Co3O4-based anode material with a hierarchical structure similar to that of a lotus pod, where single yolk–shell-structured Co3O4@Co3O4 nanospheres are well embedded in a nitrogen-doped carbon (N–C) conductive framework (Co3O4@Co3O4/N–C). This distinctive architecture contains multiple advantages of both the yolk–shell structure and conductive N–C framework to improve the Li ion storage performance. Especially, the doping of the N atom in N–C increases the interaction between the carbon and adsorbents, which is confirmed by the theoretical calculations in this work, making the carbon framework much more electrochemically active. As a result, the Co3O4@Co3O4/N–C exhibits fast surface-controlled kinetics, which corroborate the high counterion mobility and the ultrafast electron-transfer kinetics of the electrode. Due to these synergetic effects, desired capacity stability (1169.6 mAh g–1 at 200 mA g–1 after 100 cycles) and superior rate performance (633.4 mAh g–1 at 10 A g–1) have been realized in this Co3O4@Co3O4/N–C electrode.
Co-reporter:Gan Jin, Haotong Wei, Zhongkai Cheng, Henan Sun, Haizhu Sun, and Bai Yang
The Journal of Physical Chemistry C 2017 Volume 121(Issue 4) pp:
Publication Date(Web):January 9, 2017
DOI:10.1021/acs.jpcc.6b07171
Due to their environmentally friendly ideology, aqueous-processed hybrid solar cells (HSCs) are favored for industrial production. However, relatively low device performance urges the progress in power conversion efficiency (PCE) for their further applications. In this work, the function of polymer and nanocrystal (NC) is studied by investigating three different device structures. The polymer (low hole mobility), which plays an important role even if the content is extremely low, is mainly responsible for enhancing the Voc and FF, while the NC (high hole mobility) is the principle part in light absorbing, carrier generating, and transporting. The intensive study of polymer and NC makes it possible to achieve high performance through adjusting the thickness of different active layers by using device structures of the cathode/electron transport layer (ETL)/NC/polymer:NC/hole transport layer (HTL)/anode. An efficient aqueous-processed HSC with PCE of 5.64% is obtained which presents the highest performance among polymer/NC HSCs to date.
Co-reporter:Lijing Wang;Hongju Zhai;Gan Jin;Xiaoying Li;Chunwei Dong;Hao Zhang;Bai Yang;Haiming Xie;Haizhu Sun
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 25) pp:16576-16585
Publication Date(Web):2017/06/28
DOI:10.1039/C7CP01687E
A novel two-step solution approach is put forward to design a unique three dimensional (3D) porous ZnO–SnS p–n heterojunction under mild conditions. This special 3D structure is induced via flower-like ZnO in which SnS serves as an efficient photosensitizer to improve the light harvesting across the whole visible range. A profound investigation of the mechanism shows that this 3D porous ZnO–SnS material effectively integrates the large surface area and high redox potential of ZnO, and wide visible-light harvesting of SnS, which largely promotes the transfer and separation rate of carriers. The systematic study on the active species generated during the photocatalysis illustrates that it is the photoelectrons, ˙OH and O2˙− that play the crucial role in the degradation of dyes. As a result, the noble-metal free photocatalyst degrades nearly 100% of rhodamine B (RhB) within 80 min and methylene blue (MB) in 40 min under visible light. The photocatalytic activity is 10 times higher than that of the pure flower-like ZnO and two times higher than that of the SnS material. Moreover, the photocatalyst is easily separated and reused at least four times without obvious change in efficiency and properties. This work provides an effective strategy for the synthesis of 3D porous p–n heterojunction semiconductor-based photocatalysts with low cost and low toxicity, which present promising applications in the field of solar energy storage and conversion.
Co-reporter:Chao-Ying Fan;Si-Yu Liu;Huan-Huan Li;Yan-Hong Shi;Han-Chi Wang;Hai-Feng Wang;Xing-Long Wu;Jing-Ping Zhang
Journal of Materials Chemistry A 2017 vol. 5(Issue 22) pp:11255-11262
Publication Date(Web):2017/06/06
DOI:10.1039/C7TA02231J
Although the composite of metal oxide and porous carbon has been confirmed as an effective material to chemically adsorb polysulfides, the low conductivity of the metal oxide results in the need for extra pathways for the diffusion of polysulfides from adsorption sites to redox-active sites. This process results in sluggish reaction kinetics and escaped polysulfides. In this work, a Gerber tree-like interlayer with multiple components was designed to fully mediate the electrochemical conversion of Li–S batteries and shorten the diffusion distance of polysulfides in the composite. The branches of the interlayer contained TiO2 and Co3O4 nanocrystals embedded into N-doped porous carbon, while the fruit was catalytic metal cobalt. The two co-existing chemical adsorbents ensure the restriction of polysulfides through S–Ti–O bonding and Lewis acid–base interaction. Moreover, the metal Co catalyzes the transformation of adsorbed polysulfides into low-order ones, which largely shortens the diffusion pathway, improving the reaction kinetics and preventing the migration of polysulfides. The cell with the interlayer exhibited outstanding electrochemical performance. After 100 cycles, a reversible capacity of 968 mA h g−1 was maintained at 0.1C with a stable capacity retention of 85%. Even at the current rate of 1C, the cell delivered a capacity of 684.5 mA h g−1 after 300 cycles.
Co-reporter:Huan-Huan Li, Lin-Lin Zhang, Chao-Ying Fan, Xing-Long Wu, Hai-Feng Wang, Xiao-Ying Li, Kang Wang, Hai-Zhu Sun and Jing-Ping Zhang
Journal of Materials Chemistry A 2016 vol. 4(Issue 6) pp:2055-2059
Publication Date(Web):07 Jan 2016
DOI:10.1039/C5TA08779A
A dissolution–recrystallization method was developed to prepare flexible paper electrodes constructed of Zn2GeO4 nanofibers anchored with amorphous carbon (ZGO/C-P) for high energy and power Li-ion batteries. The ZGO/C-P exhibits superior long-term cycle stability (up to 2000 cycles at 1 A g−1) and excellent rate capability.
Co-reporter:Huan-Huan Li, Zi-Yao Li, Xing-Long Wu, Lin-Lin Zhang, Chao-Ying Fan, Hai-Feng Wang, Xiao-Ying Li, Kang Wang, Hai-Zhu Sun and Jing-Ping Zhang
Journal of Materials Chemistry A 2016 vol. 4(Issue 21) pp:8242-8248
Publication Date(Web):18 Apr 2016
DOI:10.1039/C6TA02417C
In recent years, metal-organic compounds have been considered as ideal sacrificial templates to obtain transition metal oxides for electrochemical applications due to their diverse structures and tunable properties. In this work, a new kind of cobalt-based metal organic compound with a layered structure was designed and prepared, which was then transformed into ultrafine cobalt oxide (Co3O4) nanocrystallites via a facile annealing treatment. The obtained Co3O4 nanocrystallites further assembled into a hierarchical shale-like structure, donating extremely short ion diffusion pathway and rich porosity to the materials. The special structure largely alleviated the problems of Co3O4 such as inferior intrinsic electrical conductivity, poor ion transport kinetics and large volume changes during the redox reactions. When evaluated as anode materials for lithium-ion batteries, the shale-like Co3O4 (S-Co3O4) exhibited superior lithium storage properties with a high capacity of 1045.3 mA h g−1 after 100 cycles at 200 mA g−1 and good rate capabilities up to 10 A g−1. Moreover, the S-Co3O4 showed decent electrochemical performance in sodium-ion batteries due to the above-mentioned comprehensive merits (380 and 153.8 mA h g−1 at 50 and 5000 mA g−1, respectively).
Co-reporter:Chao-Ying Fan, Si-Yu Liu, Huan-Huan Li, Hai-Feng Wang, Han-Chi Wang, Xing-Long Wu, Hai-Zhu Sun, and Jing-Ping Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 42) pp:28689
Publication Date(Web):October 12, 2016
DOI:10.1021/acsami.6b10515
The synergistic design of cathode region was conducted to minimize the shuttle effect of polysulfides and decrease the loading of inactive components in order to acquire high-energy-density lithium–sulfur (Li–S) batteries. The well-designed cathode region presented two special characteristics: one was the intertwined nanofibers interlayer based on ultrafine TiO2 nanocrystal uniformly embedded within N-doping porous carbon; the other was the lightweight and three-dimensional current collector of fibrous cellulose paper coated by reduced graphene oxide. In consequence, the decent reversible capacity of 874.8 mA h g–1 was acquired at 0.1 C with a capacity retention of 91.83% after 100 cycles. Besides, the satisfactory capacity of 670 mA h g–1 was delivered after 300 cycles at 1 C with the small decay rate of only 0.08%. Because of higher capacity and lower loading of inactive component in cathode region, the energy density of cell increased more than five times compared with unmodified cell. Moreover, to further enhance the energy density, the high-sulfur-loading electrode was fabricated. A good areal capacity of 4.27 mA h cm–2 was retained for the cell with the active material of 4 mg cm–2 and the cycle stability was also well-maintained. In addition, due to the flexibility of interlayer and current collector, Li–S full cell (in pouch cell format) was easily curved. Therefore, the synergistic design for cathode region, which combines the flexible and mass-produced interlayer and current collector together, provides an effective access to Li–S batteries with high energy density and flexibility for practical application.Keywords: cathode region; high energy density; lightweight current collector; Li−S batteries; TiO2 interlayer
Co-reporter:Lin-Lin Zhang, Huan-Huan Li, Yan-Hong Shi, Chao-Ying Fan, Xing-Long Wu, Hai-Feng Wang, Hai-Zhu Sun, and Jing-Ping Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 6) pp:4233
Publication Date(Web):January 27, 2016
DOI:10.1021/acsami.5b12484
In this paper, gelatin as a natural biomass was selected to successfully prepare an oxygen-enriched carbon with layered sedimentary rocks structure, which exhibited ultrahigh-rate performance and excellent cycling stability as supercapacitors. The specific capacitance reached 272.6 F g–1 at 1 A g–1 and still retained 197.0 F g–1 even at 100 A g–1 (with high capacitance retention of 72.3%). The outstanding electrochemical performance resulted from the special layered structure with large surface area (827.8 m2 g–1) and high content of oxygen (16.215 wt %), which effectively realized the synergistic effects of the electrical double-layer capacitance and pseudocapacitance. Moreover, it delivered an energy density of 25.3 Wh kg–1 even with a high power density of 34.7 kW kg–1 and ultralong cycling stability (with no capacitance decay even over 10 000 cycles at 2 A g–1) in a symmetric supercapacitor, which are highly desirable for their practical application in energy storage devices and conversion.Keywords: biomass; layered sedimentary rocks structure; oxygen-enriched; symmetric supercapacitor; ultrahigh-rate performance
Co-reporter:Huan-Huan Li, Xing-Long Wu, Lin-Lin Zhang, Chao-Ying Fan, Hai-Feng Wang, Xiao-Ying Li, Hai-Zhu Sun, Jing-Ping Zhang, and Qingyu Yan
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 46) pp:31722
Publication Date(Web):November 2, 2016
DOI:10.1021/acsami.6b11503
In this work, carbon-free, porous, and micro/nanostructural Zn2GeO4 nanofibers (p-ZGONFs) have been prepared via a dissolution-recrystallization-assisted electrospinning technology. The successful electrospinning to fabricate the uniform p-ZGONFs mainly benefits from the preparation of completely dissolved solution, which avoids the sedimentation of common Ge-containing solid-state precursors. Electrochemical tests demonstrate that the as-prepared p-ZGONFs exhibit superior Li-storage properties in terms of high initial reversible capacity of 1075.6 mA h g–1, outstanding cycling stability (no capacity decay after 130 cycles at 0.2 A g–1), and excellent high-rate capabilities (e.g., still delivering a capacity of 384.7 mA h g–1 at a very high current density of 10 A g–1) when used as anode materials for lithium ion batteries (LIBs). All these Li-storage properties are much better than those of Zn2GeO4 nanorods prepared by a hydrothermal process. The much enhanced Li-storage properties should be attributed to its distinctive structural characteristics including the carbon-free composition, plentiful pores, and macro/nanostructures. Carbon-free composition promises its high theoretical Li-storage capacity, and plentiful pores cannot only accommodate the volumetric variations during the successive lithiation/delithiation but can also serve as the electrolyte reservoirs to facilitate Li interaction with electrode materials.Keywords: anode materials; carbon-free; electrospinning; lithium ion batteries; Zn2GeO4
Co-reporter:Gan Jin, Zhaolai Chen, Chunwei Dong, Zhongkai Cheng, Xiaohang Du, Qingsen Zeng, Fangyuan Liu, Haizhu Sun, Hao Zhang, and Bai Yang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 11) pp:7101
Publication Date(Web):March 2, 2016
DOI:10.1021/acsami.6b00155
A novel kind of hybrid solar cell (HSC) was developed by introducing water-soluble insulating polymer poly(vinyl alcohol) (PVA) into nanocrystals (NCs), which revealed that the most frequently used conjugated polymer could be replaced by an insulating one. It was realized by strategically taking advantage of the characteristic of decomposition for the polymer at annealing temperature, and it was interesting to discover that partial decomposition of PVA left behind plenty of pits on the surfaces of CdTe NC films, enlarging surface contact area between CdTe NCs and subsequently evaporated MoO3. Moreover, the residual annealed PVA filled in the voids among spherical CdTe NCs, which led to the decrease of leakage current. An improved shunt resistance (increased by ∼80%) was achieved, indicating the charge-carrier recombination was effectively overcome. As a result, the new HSCs were endowed with increased Voc, fill factor, and power conversion efficiency compared with the pure NC device. This approach can be applied to other insulating polymers (e.g., PVP) with advantages in synthesis, type, economy, stability, and so on, providing a novel universal cost-effective way to achieve higher photovoltaic performance.Keywords: aqueous-processed; hybrid; nanocrystal; polymer; solar cell
Co-reporter:Chao-Ying Fan, Hai-Yan Yuan, Huan-Huan Li, Hai-Feng Wang, Wen-Liang Li, Hai-Zhu Sun, Xing-Long Wu, and Jing-Ping Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 25) pp:16108-16115
Publication Date(Web):June 10, 2016
DOI:10.1021/acsami.6b04578
In this work, the lightweight and scalable organic macromolecule graphitic carbon nitride (g-C3N4) with enriched polysulfide adsorption sites of pyridinic-N was introduced to achieve the effective functionalization of separator at the molecular level. This simple method overcomes the difficulty of low doping content as well as the existence of an uncontrolled form of nitrogen heteroatom in the final product. Besides the conventional pyridinic–N-Li bond formed in the vacancies of g-C3N4, the C–S bond was interestingly observed between g-C3N4 and Li2S, which endowed g-C3N4 with an inherent adsorption capacity for polysulfides. In addition, the microsized g-C3N4 provided the coating layer with good mechanical strength to guarantee its restriction function for polysulfides during long cycling. As a result, an excellent reversible capacity of 840 mA h g–1 was retained at 0.5 C after 400 cycles for a pure sulfur electrode, much better than that of the cell with an innocent carbon-coated separator. Even at a current density of 1 C, the cell still delivered a stable capacity of 732.7 mA h g–1 after 500 cycles. Moreover, when further increasing the sulfur loading to 5 mg cm–2, an excellent specific capacity of 1134.7 mA h g–1 was acquired with the stable cycle stability, ensuring a high areal capacity of 5.11 mA h cm–2. Besides the intrinsic adsorption ability for polysulfides, g-C3N4 is nontoxic and mass produced. Therefore, a scalable separator decorated with g-C3N4 and a commercial sulfur cathode promises high energy density for the practical application of Li–S batteries.
Co-reporter:Kang Wang, Yan-Hong Shi, Huan-Huan Li, Hai-Feng Wang, Xiao-Ying Li, Hai-Zhu Sun, Xing-Long Wu, Hai-Ming Xie, Jing-Ping Zhang, Jia-Wei Wang
Electrochimica Acta 2016 Volume 215() pp:267-275
Publication Date(Web):10 October 2016
DOI:10.1016/j.electacta.2016.08.085
A novel kind of MnCO3 nanoplatelets-reduced graphene oxide (RGO) composites, as an anode material in rechargeable Li-ion battery, was prepared by a simple low temperature reaction route. The graphene not only provided an avenue for the transport of Li-ion, but also buffered the volume expansion of MnCO3 nanoplatelets during charge and discharge. Compared to pure MnCO3 nanoplatelets, MnCO3-RGO composites presented the improved electrochemical performances. At a low current density of 100 mA g−1, MnCO3-RGO composites delivered a desired performance of 849.1 mAh g−1 after 200 cycles. When at a high current density of 500 mA g−1, the discharge capacity still maintained at 810.9 mAh g−1 after 700 cycles. Our experimental results suggest that this composite will be a candidate as a novel anode material for the power batteries of electric vehicles and the energy storage batteries of smart grids in the future.A novel kind of MnCO3 nanoplatelets-reduced graphene oxide (RGO) composite was prepared by a simple low temperature reaction route which presented improved rate performance.
Co-reporter:Dr. Chao-Ying Fan;Dr. Huan-Huan Li;Dr. Hai-Feng Wang;Dr. Hai-Zhu Sun;Dr. Xing-Long Wu; Jing-Ping Zhang
ChemSusChem 2016 Volume 9( Issue 12) pp:1483-1489
Publication Date(Web):
DOI:10.1002/cssc.201600184
Abstract
Inspired by the preparation of the hierarchically-porous carbon (HPC) derived from metal organic frameworks (MOFs) for energy storage, in this work, a simple iron-based metal– organic complex (MOC), which was simpler and cheaper compared with the MOF, was selected to achieve versatile energy storage. The intertwined 1 D nanospindles and enriched-oxygen doping of the HPC was obtained after one-step carbonization of the MOC. When employed in lithium-ion batteries, the HPC exhibited reversible capacity of 778 mA h g−1 after 60 cycles at 50 mA g−1. Moreover, the HPC maintained a capacity of 188 mA h g−1 after 400 cycles at 100 mA g−1 as the anode material in a sodium-ion battery. In addition, the HPC served as the cathode matrix for evaluation of a lithium–sulfur battery. The general preparation process of the HPC is commercial, which is responsible for the large-scale production for its practical application.
Co-reporter:Jian Zhang, Ji Qi, Shusen Kang, Haizhu Sun and Mao Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 20) pp:5214-5219
Publication Date(Web):15 Apr 2015
DOI:10.1039/C5TC00238A
Assembling multiple nanomaterials into a single nanostructure is a promising way to obtain a multifunctionality derived from each building block. We address here the need for a general all-solution processed strategy to control the fabrication of multiple nanoparticles (NPs) at room temperature and under vacuum free conditions. The monodisperse multiple NPs were integrated successively into thin bulk-hybrid gradient or periodic tandem multilayer films through tuning the cycling number of cyclic voltammetry (CV), which are based on the quantitatively electrochemical deposition of each type of NPs thanks to the electrochemical coupling reaction of the N-alkylcarbazole ligand. This simple method yields nanoporous, transparent, stable and photoactive films with a hierarchical structure of multiple uniform NPs, exemplified by the prototype photodetector devices. Significantly, this strategy opens an avenue to fabricate low-cost wire and 3-dimensional NPs films on physically flexible conducting substrates.
Co-reporter:Chao-Ying Fan, Pin Xiao, Huan-Huan Li, Hai-Feng Wang, Lin-Lin Zhang, Hai-Zhu Sun, Xing-Long Wu, Hai-Ming Xie, and Jing-Ping Zhang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 50) pp:27959
Publication Date(Web):December 1, 2015
DOI:10.1021/acsami.5b10300
In this work, the chemical interaction of cathode and lithium polysulfides (LiPSs), which is a more targeted approach for completely preventing the shuttle of LiPSs in lithium–sulfur (Li–S) batteries, has been established on the electrode level. Through simply posttreating the ordinary sulfur cathode in atmospheric environment just for several minutes, the Au nanoparticles (Au NPs) were well-decorated on/in the surface and pores of the electrode composed of commercial acetylene black (CB) and sulfur powder. The Au NPs can covalently stabilize the sulfur/LiPSs, which is advantageous for restricting the shuttle effect. Moreover, the LiPSs reservoirs of Au NPs with high conductivity can significantly control the deposition of the trapped LiPSs, contributing to the uniform distribution of sulfur species upon charging/discharging. The slight modification of the cathode with <3 wt % Au NPs has favorably prospered the cycle capacity and stability of Li–S batteries. Moreover, this cathode exhibited an excellent anti-self-discharge ability. The slight decoration for the ordinary electrode, which can be easily accessed in the industrial process, provides a facile strategy for improving the performance of commercial carbon-based Li–S batteries toward practical application.Keywords: anti-self-discharge; Au nanoparticles; chemical Au−S interaction; Li−S batteries; postdecorated cathodes
Co-reporter:Hong-Tao Cao, Lei Ding, Guo-Gang Shan, Hai-Zhu Sun, Yong Wu and Zhong-Min Su
Dalton Transactions 2015 vol. 44(Issue 46) pp:19997-20003
Publication Date(Web):19 Oct 2015
DOI:10.1039/C5DT03129J
A sulfur-free iridium(III) complex (pbi)2Ir(mtpy) (1) was successfully prepared and adopted as a Hg(II)-chemosensor with high selectivity and sensitivity. Multi-signaling responses towards Hg(II) ions were observed by UV−vis absorption, phosphorescence and electrochemistry measurements. With addition of Hg(II) ions, complex 1 presented quenched emission in its phosphorescence spectrum and the detection limit was as low as 2.5 × 10−7 M. Additionally, its redox peak currents showed a broad linear relationship with the concentration of Hg(II) ions ranging from 0 to 500 μM, which was beneficial for the quantitative detection. Based on the 1H NMR and ESI-MS analyses, the probing mechanism was tentatively supposed to be the Hg2+-induced changes in the local environment of complex 1. Such a response process was useful for achieving simple and effective detection of Hg(II) ions as well as developing more chemosensors.
Co-reporter:Huan-Huan Li, Lin-Lin Zhang, Chao-Ying Fan, Kang Wang, Xing-Long Wu, Hai-Zhu Sun and Jing-Ping Zhang
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 35) pp:22893-22899
Publication Date(Web):31 Jul 2015
DOI:10.1039/C5CP03505H
A novel kind of plum-pudding like mesoporous SiO2 nanospheres (MSNs) and flake graphite (FG) nanocomposite (pp-MSNs/FG) was designed and fabricated via a facile and cost-effective hydrothermal method. Transmission electron microscopy (TEM) analysis showed that most of the MSNs were well anchored on FG. This special architecture has multiple advantages, including FG that offers a conductive framework and hinders the volume expansion effect. Moreover, the porous structure of MSNs could provide more available lithium storage sites and extra free space to accommodate the mechanical strain caused by the volume change during the repeated reversible reaction between Li+ and active materials. Due to the synergetic effects of its unique plum-pudding structure, the obtained pp-MSNs/FG nanocomposite exhibited a decent reversible capacity of 702 mA h g−1 (based on the weight of MSNs in the electrode material) after 100 cycles with high Coulombic efficiency above 99% under 100 mA g−1 and a charge capacity of 239.6 mA h g−1 could be obtained even under 5000 mA g−1. Their high rate performance is among the best-reported performances of SiO2-based anode materials.
Co-reporter:Chao-Ying Fan, Huan-Huan Li, Lin-Lin Zhang, Hai-Zhu Sun, Xing-Long Wu, Hai-Ming Xie and Jing-Ping Zhang
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 36) pp:23481-23488
Publication Date(Web):06 Aug 2015
DOI:10.1039/C5CP02531A
The effect of graphene lateral size on the electrochemical performance of lithium–sulfur (Li–S) batteries is often ignored. In this study, the thermally exfoliated large lateral-sized graphene (denoted LTG) was employed as the conductive matrix to support sulfur, and its performance was then compared with that of a smaller lateral-sized graphene (denoted STG) for Li–S batteries. The results showed that the LTG–S composite exhibited much higher capacity retention (53%) versus the STG–S (29%) and better rate capabilities. Because they were both identical in morphology, in terms of sulfur content and sulfur distribution, the improved properties probably resulted from the potential prevention of polysulfide diffusion upon cycling due to the larger graphene-based network and higher aspect ratio of the LTG matrix, referred as better polysulfide reservoirs. To further improve the cell performance, a reduced graphene oxide-coated carbon fiber paper (RCF) was inserted between the LTG–S cathode and the separator by a simple drop-coat method, which provided an increased conductive surface area for polysulfides to be oxidized/reduced and buffered volume expansion. As expected, the discharge capacities of 1143 and 622 mA h g−1 at first use and after 100th cycles were obtained with an average Coulombic efficiency of 99.7%, which were higher than 847 and 455 mA h g−1 for the cathode without the RCF, respectively. This study highlights the significance of large graphene sheets and interlayers on the inhibition of polysulfide diffusion and offers a new way to solve the problems of Li–S batteries.
Co-reporter:Hong-Tao Cao, Guo-Gang Shan, Yong-Ming Yin, Hai-Zhu Sun, Yong Wu, Wen-Fa Xie, Zhong-Min Su
Dyes and Pigments 2015 Volume 112() pp:8-16
Publication Date(Web):January 2015
DOI:10.1016/j.dyepig.2014.06.014
•Four Ir(III)-based dyes with 1,2-diphenyl-1H-benzoimidazole ligands were prepared.•They displayed green emissions around 492 nm with high quantum yields in CH2Cl2.•Their electroluminescence properties were successfully investigated.•A non-doped device displayed high efficiencies of 19.8 cd A−1 and 20.4 lm W−1.•A device simultaneously displayed low efficiency roll-off at high luminance.Four novel iridium(III) complexes containing 1,2-diphenyl-1H-benzoimidazole as cyclometalated ligands were successfully synthesized and characterized. The complexes displayed strong emissions around 492 nm with high photoluminescence quantum yields of 70–92% in dichloromethane solution at 298 K. Doped OLEDs based on the complexes were prepared, which showed a peak current efficiency of 34.5 cd A−1, power efficiency of 40.1 lm W−1. Non-doped OLEDs using the complexes as emitters were then fabricated for further investigation of their electroluminescence properties. Encouragingly, one non-doped device possessed outstanding performance with a maximum current efficiency of 19.8 cd A−1 and power efficiency of 20.4 lm W−1 whilst simultaneously displaying low efficiency roll-off at high luminance.Novel kinds of iridium(III) complexes with 1,2-diphenyl-1H-benzoimidazole ligands were prepared to fabricate high-performance non-doped OLEDs, which showed favorable performance with a maximum ηc of 19.8 cd A−1 and ηp of 20.4 lm W−1 accompanied by low efficiency roll-off at high luminance.
Co-reporter:Hong-Tao Cao, Guo-Gang Shan, Yong-Ming Yin, Hai-Zhu Sun, Yong Wu, Wen-Fa Xie, Zhong-Min Su
Dyes and Pigments 2015 Volume 113() pp:655-663
Publication Date(Web):February 2015
DOI:10.1016/j.dyepig.2014.10.003
•Three Ir(III)-based dyes with N-heterocyclic phenyltriazole ligands are prepared.•They display blue emissions at 460–466 nm in CH2Cl2 at 298 K.•Their photoluminescence and electroluminescence properties are investigated.•They possess increased photoluminescence efficiencies with 14% and 18%.•They exhibit improved electroluminescence efficiencies with 4.1 and 4.6 lm W−1.Novel kinds of blue-emitting heteroleptic iridium(III) complexes (fpdmtz)2Ir(mpypz) (1), (fpmptz)2Ir(mpypz) (2) and (fpmptz)2Ir(pypz) (3) with N-heterocyclic phenyltriazole ligands were designed and synthesized under the guidance of theoretical calculations. Especially, the effect of substituent groups on their emission properties was systematically studied through introducing methyl and propyl moieties into the cyclometalated and ancillary ligands. The experimental results showed that 2 and 3 modified by propyl groups exhibited higher photoluminescence and electroluminescence efficiencies than 1 modified by methyl moiety in its cyclometalated ligands. Such greatly improved emission efficiencies were tentatively attributed to the suppressed intermolecular interactions in solid state caused by the introduction of propyl group, indicating that the photoluminescence and electroluminescence properties of iridium(III) complexes can be manipulated just by modifying simple small molecule groups into the cyclometalated ligands.Novel kinds of blue-emitting iridium(III) complexes adopting N-heterocyclic phenyltriazole ligands were designed and synthesized, which showed improved efficiencies through introducing propyl group into the cyclometalated ligands.
Co-reporter:Gan Jin;Dr. Li-Ming Jiang;Dong-Mei Yi;Dr. Hai-Zhu Sun; Hong-Chen Sun
ChemPhysChem 2015 Volume 16( Issue 17) pp:3687-3694
Publication Date(Web):
DOI:10.1002/cphc.201500715
Abstract
To impart biocompatibility, stability, and specificity to quantum dots (QDs)—and to reduce their toxicity—it is essential to carry out surface modification. However, most surface-modification processes are costly, complicated, and time-consuming. In addition, the modified QDs often have a large size, which leads to easy aggregation in biological environments, making it difficult to excrete them from in vivo systems. To solve these problems, three kinds of conventional polymers, namely, polyvinyl alcohol (PVA, neutral), sodium polystyrene sulfonate (PSS, negative charged), and poly(diallyl dimethyl ammonium chloride) (PDDA, positive charged) were selected to modify the surface of QDs at low cost via a simple process in which the size of the QDs was kept small after modification. The effect of polymer modification on the photoluminescence (PL) properties of the QDs was systematically investigated. High quantum yields (QYs) of 65 % were reached, which is important for the realization of bio-imaging. Then, the cytotoxicity of CdTe QD–polymer composites was systematically investigated via MTT assay using the Cal27 and HeLa cell lines, especially for high concentrations of QD–polymer composites in vitro. The experimental results showed that the cytotoxicity decreased in the order CdTe-PDDA>CdTe>CdTe-PSS>CdTe-PVA, indicating that PSS and PVA can reduce the toxicity of the QDs. An obvious cytotoxicity of CdTe-PVA and CdTe-PSS was present until 120 h for the Cal27 cell line and until 168 h for the HeLa cell line. At last, the Cal27 cell line was selected to realize bio-imaging using CdTe-PSS and CdTe-PVA composites with different emission colors under one excitation wavelength.
Co-reporter:Huan-Huan Li
The Journal of Physical Chemistry C 2015 Volume 119(Issue 7) pp:3495-3501
Publication Date(Web):January 23, 2015
DOI:10.1021/jp511435w
Mesoporous SiO2 nanospheres (MSNs) and carbon nanocomposite with dual-porosity structure (DMSNs/C) were synthesized via a straightforward approach. Both MSNs and DMSNs/C showed uniform pore size distribution, high specific surface area, and large pore volume. When evaluated as an anode material for lithium ion batteries (LIBs), the DMSNs/C nanocomposite not only delivered an impressive reversible capacity of 635.7 mAh g–1 (based on the weight of MSNs in the electrode material) over 200 cycles at 100 mA g–1 with Coulombic efficiency (CE) above 99% but also exhibited excellent rate capability. The significant improvement of the electrochemical performance was attributed to synergetic effects of the dual-mesoporous structure and carbon coating layer: (i) the dual-porosity structure could increase the contact area and facilitate Li+ diffusion at the interface between the electrolyte and active materials, as well as buffer the volume change of MSNs, and (ii) the homogeneous carbon coating represented an excellent conductive layer, thus significantly speeding the lithiation process of the MSNs significantly, while further restraining the volume expansion. Considering the facile preparation and good lithium storage abilities, the DMSNs/C nanocomposite holds promise in applications in practical LIBs.
Co-reporter:Fei Zhai;Hao-tong Wei;Su-mei Zhan;Gan Jin
Chinese Journal of Polymer Science 2015 Volume 33( Issue 2) pp:215-223
Publication Date(Web):2015 February
DOI:10.1007/s10118-015-1574-6
A novel kind of ligand free aurum nanoparticles (Au NPs)/poly(p-phenylene-vinylene) (PPV) composites was prepared via a simple approach. Although there were no ligands coating on the surface of the Au NPs, the Au NPs/PPV precursor composite exhibited excellent stability that no obvious variance was found as long as 6 months at ∼4 °C in aqueous and alcohol mixed solutions. This was attributed to the strong interaction between Au NPs and PPV precursor, which was further strengthened after heat transformation. Fourier transform infrared (FTIR) and Raman spectra showed the interaction between benzene ring in PPV and Au NPs led to the part transformation of the sp2 hybrid orbital into the sp3 one during the composite formation. As a result, the photoluminescence (PL) life time of PPV in the composite was longer than that of pure PPV. The Au NPs/PPV composite exhibited good photo-electric response, indicating their potential application in the area of the photoelectric conversion devices.
Co-reporter:Gan Jin, Hao-Tong Wei, Tian-Yi Na, Hai-Zhu Sun, Hao Zhang, and Bai Yang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 11) pp:8606
Publication Date(Web):May 8, 2014
DOI:10.1021/am501408v
Aqueous-processed solar cells have evolved into a new generation of promising and renewable energy materials due to their excellent optical, electrical, and low-cost properties. In this work, Cd0.75Hg0.25Te colloid quantum dots (CQDs) were incorporated into a water-soluble conjugated polymer with broad absorption and high charge-carrier-mobility (5 × 10–4 cm2 V–1 s–1) to obtain a composite with an absorption spectrum ranging from 300 to 1200 nm. The matched energy level between polymer and CQDs ensured the effective electron transfer, while the interpenetrating network structure formed via heat treatment guaranteed the quick electron transport. Moreover, the formation process of the interpenetrating network was systematically monitored by using AFM and TEM instruments and further confirmed through the measurement of charge-carrier-mobility of the active layers. In combination with the surface modification of a single Cd0.75Hg0.25Te layer, this aqueous-processed solar cell showed excellent photovoltaic response and the power conversion efficiency (PCE) reached 2.7% under AM 1.5 G illumination (100 mW cm–2). Especially, the contribution of the Herschel infrared region (780–1100 nm) to the photocurrent was as high as 15.04%. This device showed the highest PCE among organic-inorganic hybrid solar cells (HSCs) based on CdxHg1–xTe CQDs and the highest near infrared (NIR) contribution among aqueous-processed HSCs, indicating the enormous potential of taking advantage of NIR energy in a solar spectrum and a promising application in solar cells especially used in cloudy weather.Keywords: aqueous-processed; colloidal quantum dots; hybrid solar cells; near infrared;
Co-reporter:Huan-Huan Li, Jia-Wei Wang, Xing-Long Wu, Hai-Zhu Sun, Feng-Mei Yang, Kang Wang, Lin-Lin Zhang, Chao-Ying Fan and Jing-Ping Zhang
RSC Advances 2014 vol. 4(Issue 68) pp:36218-36225
Publication Date(Web):06 Aug 2014
DOI:10.1039/C4RA07043G
A novel method was developed to successfully prepare mesoporous Si/C nanocomposites with yolk–shell structures (MSi@C). Different from the reported methods, this approach was unique, straightforward and easily scaled up. A plausible mechanism for the formation of MSi@C nanocomposites was proposed, which was in accordance with the results of transmission electron microscopy (TEM). When the mixture of mesoporous Si (M-Si) and citric acid was heated up, the volume of air adsorbed by the M-Si expanded, and the viscoelastic citric acid layers inflated just like balloons, directly leading to the formation of the yolk–shell structured MSi@C nanocomposites during the carbonization. The MSi@C nanocomposites possessed an M-Si core with diameter ∼150 nm and a carbon shell with diameter ∼230 nm. Such nano and mesoporous structure combined with voids between the M-Si core and carbon shell not only provides enough space for the volume expansion of M-Si during lithiation, but also accommodates the mechanical stresses/strains caused by the volume inflation and contraction. Moreover, partial graphitization of the carbon contributed to the improved electrical conductivity and rate performance of MSi@C. As a result, the prepared MSi@C exhibited an initial reversible capacity of 2599.1 mA h g−1 and maintained 1264.7 mA h g−1 even after 150 cycles at 100 mA g−1, with high coulombic efficiency (CE) above 99% (based on the weight of M-Si in the electrode). Therefore, this work provided an alternative method to fabricate yolk–shell nanostructured materials with great potential as anode materials for lithium ion batteries.
Co-reporter:Guolong Huang, Wei Li, Haizhu Sun, Jiawei Wang, Jingping Zhang, Huixin Jiang, Fei Zhai
Electrochimica Acta 2013 Volume 97() pp:92-98
Publication Date(Web):1 May 2013
DOI:10.1016/j.electacta.2013.02.066
Although it is difficult to obtain LiFePO4/C particles with diameter less than 100 nm via solid state reaction, a simple, low cost and easily scaled-up method assisted by polyvinylpyrrolidone (PVP) was developed for mass production of nano-LiFePO4/C composites with average diameter of 80 nm in this study. Moreover, a homogeneous carbon layer (about 2 nm) was successfully coated on nano-LiFePO4 particle surface, which was difficult without PVP assistance. The combination of nano size and uniform carbon coating is important for the improvement of LiFePO4 electrochemical performance, especially the performance at low temperature. As a result, the obtained nano-LiFePO4/C composite possessed high discharge capacity of 160 mAh g−1 at 0.1 C. The capacity retention of the composite was kept over 120 mAh g−1 even at low temperature of −20 °C with the discharge rate of 0.1 C. In addition, the nano-LiFePO4/C composite showed excellent low temperature cycling performance with less than 3% capacity fading after 500 cycles at 0.6 C. The nano-sized cathode material via such simple method is beneficial for the application in electric vehicles as well as hybrid electric vehicles.A simple, low cost and easily scaled-up method assisted by polyvinylpyrrolidone (PVP) was developed for mass production of nano-LiFePO4/C composites with average diameter of 80 nm with good electrochemical performance especially at low temperature.
Co-reporter:Wenjing Cai, Liming Jiang, Dongmei Yi, Haizhu Sun, Haotong Wei, Hao Zhang, Hongchen Sun, and Bai Yang
Langmuir 2013 Volume 29(Issue 12) pp:4119-4127
Publication Date(Web):March 4, 2013
DOI:10.1021/la3049696
High quality CdHgTe quasi core/shell nanocrystals (NCs) were prepared via the one-step method. The relationship between the composition, structure, and property was systematically investigated by the combination of X-ray photoelectron spectroscopy (XPS), inductively coupled plasma atomic emission (ICP), and the photoluminescence (PL) measurements. The quantum yield (QY) was ∼50% when the feed ratio of Cd2+ to Hg2+ was equal to 1. The PL property was further polished, and the QY was improved to ∼80% through the variance of the prepared conditions such as the ratio of ligand to metal ion and HTe– to metal ion, pH value, and temperature. In addition, the cytotoxic effects of CdHgTe NCs were systematically studied. The results showed that, for Cd0.21Hg0.79Te NCs, its quasi core/shell structure was very stable and little cadmium ions were released. As a result, such NCs showed little cytotoxicity and would find applications in tissue imaging or detection.
Co-reporter:Zhaolai Chen, Jing Li, Xue Zhang, Zhennan Wu, Hao Zhang, Haizhu Sun and Bai Yang
Physical Chemistry Chemical Physics 2012 vol. 14(Issue 17) pp:6119-6125
Publication Date(Web):08 Mar 2012
DOI:10.1039/C2CP40377C
Creation of nanoparticle (NP) architectures via a self-assembly strategy is the current means to integrate and/or modulate the functionalities of NPs. In this paper, we demonstrate the capability for constructing NP spherical superstructures through the specific interaction between host and guest molecules, for instance the model system of α-cyclodextrin (α-CD) and oleic acid (OA), which are decorated on two different NPs beforehand. Subsequently, the OA-decorated hydrophobic NPs are dispersed in hexane, whereas the α-CD-decorated NPs are dispersed in water. The blending of these two immiscible solutions produces NP binary superstructures because of the multiple linkages between the α-CD- and OA-decorated NPs. Control experiments indicate that the self-assembly of NPs occurs either at the hexane/water interface to form hybrid films or in the aqueous phase to generate spherical architectures, which strongly depends on the amount and the size of α-CD-decorated NPs. The high ratio and small size of the α-CD-decorated NPs facilitate the formation of spherical architectures. Competitive experiments with the addition of host α-CD and guest sodium oleate clearly confirm that the main driving force for the NP co-assembly is the specific interaction between α-CD and OA. In addition, the flexible decoration of α-CD and OA on the NPs makes the current strategy generally applicable for a variety of NPs, such as the superstructures of Au/Fe3O4, Pt/Fe3O4, and Au/NaYF4:Yb,Tm, which is expected to promote the further application of NPs in environmental and biological sciences.
Co-reporter:Hong-Tao Cao, Lei Ding, Guo-Gang Shan, Hai-Zhu Sun, Yong Wu and Zhong-Min Su
Dalton Transactions 2015 - vol. 44(Issue 46) pp:NaN20003-20003
Publication Date(Web):2015/10/19
DOI:10.1039/C5DT03129J
A sulfur-free iridium(III) complex (pbi)2Ir(mtpy) (1) was successfully prepared and adopted as a Hg(II)-chemosensor with high selectivity and sensitivity. Multi-signaling responses towards Hg(II) ions were observed by UV−vis absorption, phosphorescence and electrochemistry measurements. With addition of Hg(II) ions, complex 1 presented quenched emission in its phosphorescence spectrum and the detection limit was as low as 2.5 × 10−7 M. Additionally, its redox peak currents showed a broad linear relationship with the concentration of Hg(II) ions ranging from 0 to 500 μM, which was beneficial for the quantitative detection. Based on the 1H NMR and ESI-MS analyses, the probing mechanism was tentatively supposed to be the Hg2+-induced changes in the local environment of complex 1. Such a response process was useful for achieving simple and effective detection of Hg(II) ions as well as developing more chemosensors.
Co-reporter:Huan-Huan Li, Lin-Lin Zhang, Chao-Ying Fan, Xing-Long Wu, Hai-Feng Wang, Xiao-Ying Li, Kang Wang, Hai-Zhu Sun and Jing-Ping Zhang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 6) pp:NaN2059-2059
Publication Date(Web):2016/01/07
DOI:10.1039/C5TA08779A
A dissolution–recrystallization method was developed to prepare flexible paper electrodes constructed of Zn2GeO4 nanofibers anchored with amorphous carbon (ZGO/C-P) for high energy and power Li-ion batteries. The ZGO/C-P exhibits superior long-term cycle stability (up to 2000 cycles at 1 A g−1) and excellent rate capability.
Co-reporter:Huan-Huan Li, Lin-Lin Zhang, Chao-Ying Fan, Kang Wang, Xing-Long Wu, Hai-Zhu Sun and Jing-Ping Zhang
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 35) pp:NaN22899-22899
Publication Date(Web):2015/07/31
DOI:10.1039/C5CP03505H
A novel kind of plum-pudding like mesoporous SiO2 nanospheres (MSNs) and flake graphite (FG) nanocomposite (pp-MSNs/FG) was designed and fabricated via a facile and cost-effective hydrothermal method. Transmission electron microscopy (TEM) analysis showed that most of the MSNs were well anchored on FG. This special architecture has multiple advantages, including FG that offers a conductive framework and hinders the volume expansion effect. Moreover, the porous structure of MSNs could provide more available lithium storage sites and extra free space to accommodate the mechanical strain caused by the volume change during the repeated reversible reaction between Li+ and active materials. Due to the synergetic effects of its unique plum-pudding structure, the obtained pp-MSNs/FG nanocomposite exhibited a decent reversible capacity of 702 mA h g−1 (based on the weight of MSNs in the electrode material) after 100 cycles with high Coulombic efficiency above 99% under 100 mA g−1 and a charge capacity of 239.6 mA h g−1 could be obtained even under 5000 mA g−1. Their high rate performance is among the best-reported performances of SiO2-based anode materials.
Co-reporter:Huan-Huan Li, Zi-Yao Li, Xing-Long Wu, Lin-Lin Zhang, Chao-Ying Fan, Hai-Feng Wang, Xiao-Ying Li, Kang Wang, Hai-Zhu Sun and Jing-Ping Zhang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 21) pp:NaN8248-8248
Publication Date(Web):2016/04/18
DOI:10.1039/C6TA02417C
In recent years, metal-organic compounds have been considered as ideal sacrificial templates to obtain transition metal oxides for electrochemical applications due to their diverse structures and tunable properties. In this work, a new kind of cobalt-based metal organic compound with a layered structure was designed and prepared, which was then transformed into ultrafine cobalt oxide (Co3O4) nanocrystallites via a facile annealing treatment. The obtained Co3O4 nanocrystallites further assembled into a hierarchical shale-like structure, donating extremely short ion diffusion pathway and rich porosity to the materials. The special structure largely alleviated the problems of Co3O4 such as inferior intrinsic electrical conductivity, poor ion transport kinetics and large volume changes during the redox reactions. When evaluated as anode materials for lithium-ion batteries, the shale-like Co3O4 (S-Co3O4) exhibited superior lithium storage properties with a high capacity of 1045.3 mA h g−1 after 100 cycles at 200 mA g−1 and good rate capabilities up to 10 A g−1. Moreover, the S-Co3O4 showed decent electrochemical performance in sodium-ion batteries due to the above-mentioned comprehensive merits (380 and 153.8 mA h g−1 at 50 and 5000 mA g−1, respectively).
Co-reporter:Zhaolai Chen, Jing Li, Xue Zhang, Zhennan Wu, Hao Zhang, Haizhu Sun and Bai Yang
Physical Chemistry Chemical Physics 2012 - vol. 14(Issue 17) pp:NaN6125-6125
Publication Date(Web):2012/03/08
DOI:10.1039/C2CP40377C
Creation of nanoparticle (NP) architectures via a self-assembly strategy is the current means to integrate and/or modulate the functionalities of NPs. In this paper, we demonstrate the capability for constructing NP spherical superstructures through the specific interaction between host and guest molecules, for instance the model system of α-cyclodextrin (α-CD) and oleic acid (OA), which are decorated on two different NPs beforehand. Subsequently, the OA-decorated hydrophobic NPs are dispersed in hexane, whereas the α-CD-decorated NPs are dispersed in water. The blending of these two immiscible solutions produces NP binary superstructures because of the multiple linkages between the α-CD- and OA-decorated NPs. Control experiments indicate that the self-assembly of NPs occurs either at the hexane/water interface to form hybrid films or in the aqueous phase to generate spherical architectures, which strongly depends on the amount and the size of α-CD-decorated NPs. The high ratio and small size of the α-CD-decorated NPs facilitate the formation of spherical architectures. Competitive experiments with the addition of host α-CD and guest sodium oleate clearly confirm that the main driving force for the NP co-assembly is the specific interaction between α-CD and OA. In addition, the flexible decoration of α-CD and OA on the NPs makes the current strategy generally applicable for a variety of NPs, such as the superstructures of Au/Fe3O4, Pt/Fe3O4, and Au/NaYF4:Yb,Tm, which is expected to promote the further application of NPs in environmental and biological sciences.
Co-reporter:Chao-Ying Fan, Si-Yu Liu, Huan-Huan Li, Yan-Hong Shi, Han-Chi Wang, Hai-Feng Wang, Hai-Zhu Sun, Xing-Long Wu and Jing-Ping Zhang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 22) pp:NaN11262-11262
Publication Date(Web):2017/05/08
DOI:10.1039/C7TA02231J
Although the composite of metal oxide and porous carbon has been confirmed as an effective material to chemically adsorb polysulfides, the low conductivity of the metal oxide results in the need for extra pathways for the diffusion of polysulfides from adsorption sites to redox-active sites. This process results in sluggish reaction kinetics and escaped polysulfides. In this work, a Gerber tree-like interlayer with multiple components was designed to fully mediate the electrochemical conversion of Li–S batteries and shorten the diffusion distance of polysulfides in the composite. The branches of the interlayer contained TiO2 and Co3O4 nanocrystals embedded into N-doped porous carbon, while the fruit was catalytic metal cobalt. The two co-existing chemical adsorbents ensure the restriction of polysulfides through S–Ti–O bonding and Lewis acid–base interaction. Moreover, the metal Co catalyzes the transformation of adsorbed polysulfides into low-order ones, which largely shortens the diffusion pathway, improving the reaction kinetics and preventing the migration of polysulfides. The cell with the interlayer exhibited outstanding electrochemical performance. After 100 cycles, a reversible capacity of 968 mA h g−1 was maintained at 0.1C with a stable capacity retention of 85%. Even at the current rate of 1C, the cell delivered a capacity of 684.5 mA h g−1 after 300 cycles.
Co-reporter:Jian Zhang, Ji Qi, Shusen Kang, Haizhu Sun and Mao Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 20) pp:NaN5219-5219
Publication Date(Web):2015/04/15
DOI:10.1039/C5TC00238A
Assembling multiple nanomaterials into a single nanostructure is a promising way to obtain a multifunctionality derived from each building block. We address here the need for a general all-solution processed strategy to control the fabrication of multiple nanoparticles (NPs) at room temperature and under vacuum free conditions. The monodisperse multiple NPs were integrated successively into thin bulk-hybrid gradient or periodic tandem multilayer films through tuning the cycling number of cyclic voltammetry (CV), which are based on the quantitatively electrochemical deposition of each type of NPs thanks to the electrochemical coupling reaction of the N-alkylcarbazole ligand. This simple method yields nanoporous, transparent, stable and photoactive films with a hierarchical structure of multiple uniform NPs, exemplified by the prototype photodetector devices. Significantly, this strategy opens an avenue to fabricate low-cost wire and 3-dimensional NPs films on physically flexible conducting substrates.
Co-reporter:Lijing Wang, Hongju Zhai, Gan Jin, Xiaoying Li, Chunwei Dong, Hao Zhang, Bai Yang, Haiming Xie and Haizhu Sun
Physical Chemistry Chemical Physics 2017 - vol. 19(Issue 25) pp:NaN16585-16585
Publication Date(Web):2017/06/05
DOI:10.1039/C7CP01687E
A novel two-step solution approach is put forward to design a unique three dimensional (3D) porous ZnO–SnS p–n heterojunction under mild conditions. This special 3D structure is induced via flower-like ZnO in which SnS serves as an efficient photosensitizer to improve the light harvesting across the whole visible range. A profound investigation of the mechanism shows that this 3D porous ZnO–SnS material effectively integrates the large surface area and high redox potential of ZnO, and wide visible-light harvesting of SnS, which largely promotes the transfer and separation rate of carriers. The systematic study on the active species generated during the photocatalysis illustrates that it is the photoelectrons, ˙OH and O2˙− that play the crucial role in the degradation of dyes. As a result, the noble-metal free photocatalyst degrades nearly 100% of rhodamine B (RhB) within 80 min and methylene blue (MB) in 40 min under visible light. The photocatalytic activity is 10 times higher than that of the pure flower-like ZnO and two times higher than that of the SnS material. Moreover, the photocatalyst is easily separated and reused at least four times without obvious change in efficiency and properties. This work provides an effective strategy for the synthesis of 3D porous p–n heterojunction semiconductor-based photocatalysts with low cost and low toxicity, which present promising applications in the field of solar energy storage and conversion.
Co-reporter:Chao-Ying Fan, Huan-Huan Li, Lin-Lin Zhang, Hai-Zhu Sun, Xing-Long Wu, Hai-Ming Xie and Jing-Ping Zhang
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 36) pp:NaN23488-23488
Publication Date(Web):2015/08/06
DOI:10.1039/C5CP02531A
The effect of graphene lateral size on the electrochemical performance of lithium–sulfur (Li–S) batteries is often ignored. In this study, the thermally exfoliated large lateral-sized graphene (denoted LTG) was employed as the conductive matrix to support sulfur, and its performance was then compared with that of a smaller lateral-sized graphene (denoted STG) for Li–S batteries. The results showed that the LTG–S composite exhibited much higher capacity retention (53%) versus the STG–S (29%) and better rate capabilities. Because they were both identical in morphology, in terms of sulfur content and sulfur distribution, the improved properties probably resulted from the potential prevention of polysulfide diffusion upon cycling due to the larger graphene-based network and higher aspect ratio of the LTG matrix, referred as better polysulfide reservoirs. To further improve the cell performance, a reduced graphene oxide-coated carbon fiber paper (RCF) was inserted between the LTG–S cathode and the separator by a simple drop-coat method, which provided an increased conductive surface area for polysulfides to be oxidized/reduced and buffered volume expansion. As expected, the discharge capacities of 1143 and 622 mA h g−1 at first use and after 100th cycles were obtained with an average Coulombic efficiency of 99.7%, which were higher than 847 and 455 mA h g−1 for the cathode without the RCF, respectively. This study highlights the significance of large graphene sheets and interlayers on the inhibition of polysulfide diffusion and offers a new way to solve the problems of Li–S batteries.
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