Liu Gang    Lichang Yin    Jian Pan    Li Feng    温磊    Zhen Chao    成会明    

Advanced Materials

2015

Electronic conduction along the [001] direction of a faceted anatase TiO2 particle in contact with two tungsten probes is found to be an order of magnitude higher than that along the [010] direction due to a smaller potential barrier of the TiO2(001)-tungsten interface for electron transport than the TiO2(010)-tungsten interface. This finding could guide the design of TiO2-based electrodes.

Liu Gang    Lichang Yin    Jian Pan    Li Feng    Wen Lei    Zhen Chao    成会明    

Advanced Materials

2015

Abstract LiFePO/C microspheres with different surface morphologies and porosities were prepared from different carbon sources. The effects of the surface morphology and pore structure of the microspheres on their electrochemical properties and electrode density were investigated. The electrochemical performance and electrode density depended on the morphology and pore structure of the LiFePO/C microspheres. Open-pore LiFePO/C microspheres with rough surfaces exhibited good adhesion with current collectors and a high electrode density (2.6 g/cm). They also exhibited high performance in a half cell and full battery with a high volumetric energy density.

温磊    Hu Xiaodong    Luo    Feng Li    成会明    

Particuology

2015

Revealing the key factors of controlling the reduction and oxidation half reactions of photocatalysis is necessary in order to obtain the implications for designing and developing efficient photocatalysts. In this work, boron-doped TiO microspheres consisting of rutile nanorods with the top reactive {111} facets were synthesized by the acidic hydrolysis of TiB. The thermal diffusion of boron from the inner to surface part of the microspheres results in switching of the preference from photocatalytic H evolution to O evolution. This switching is caused by the downward shift of surface band edges with the incorporation of boron in surface.

Wu Ting-Ting    Xie Ying-Peng    Lichang Yin    Gang Liu    成会明    

Journal of Physical Chemistry C

2015

To achieve the long-term oxidation protection of carbon/carbon composites at low and medium temperatures, a SiC/BC-BO-SiO-AlO coating was applied on the composites. The coating exhibits a dual-layer structure with a dense SiC inner layer and BC-BO-SiO-AlO multi-phase outer layer. The effects of AlO contents and oxidation temperatures on the oxidation behavior of the coated C/C were investigated. The results shows that the coating with 7.7wt.% AlO performs excellent self-healing ability and can protect the C/C composites with weight losses of less than 1% for 250h at 800°C and for 90h at 900°C and 1000°C.

Hu Chenglong    Pang Shengyang    Tang Sufang    Yang Zhi    Wang Shijun    成会明    

Corrosion Science

2015

Silicon has the highest theoretical lithium storage capacity of all materials at 4200 mAh/g; therefore, it is considered to be a promising candidate as the anode of high-energy-density lithium-ion batteries (LIBs). However, serious volume changes caused by lithium insertion/deinsertion lead to a rapid decay of the performance of the Si anode. Here, a Si nanoparticle (NP)-filled carbon nanotube (CNT) material was prepared by chemical vapor deposition, and a nanobattery was constructed inside a transmission electron microscope (TEM) using the Si NP-filled CNT as working electrode to directly investigate the structural change of the Si NPs and the confinement effect of the CNT during the lithiation and delithiation processes. It is found that the volume expansion (∼180%) of the lithiated Si NPs is restricted by the wall of the CNTs and that the CNT can accommodate this volume expansion without breaking its tubular structure. The Si NP-filled CNTs showed a high reversible lithium storage capacity and desirable high rate capability, because the pulverization and exfoliation of the Si NPs confined in CNTs were efficiently prevented. Our results demonstrate that filling CNTs with high-capacity active materials is a feasible way to make high-performance LIB electrode materials, taking advantage of the unique confinement effect and good electrical conductivity of the CNTs.

Wanjing Yu    Chang Liu    Pengxiang Hou    Lili li Zhang    Shan Xuyi    Li Feng    成会明    

ACS Nano

2015

Large-area monolayer WS is a desirable material for applications in next-generation electronics and optoelectronics. However, the chemical vapour deposition (CVD) with rigid and inert substrates for large-area sample growth suffers from a non-uniform number of layers, small domain size and many defects, and is not compatible with the fabrication process of flexible devices. Here we report the self-limited catalytic surface growth of uniform monolayer WS single crystals of millimetre size and large-area films by ambient-pressure CVD on Au. The weak interaction between the WS and Au enables the intact transfer of the monolayers to arbitrary substrates using the electrochemical bubbling method without sacrificing Au. The WS shows high crystal quality and optical and electrical properties comparable or superior to mechanically exfoliated samples. We also demonstrate the roll-to-roll/bubbling production of large-area flexible films of uniform monolayer, double-layer WS and WS /graphene heterostructures, and batch fabrication of large-area flexible monolayer WS film transistor arrays.

Yang Gao    Zhibo Liu    Sun Dong-ming    Le Huang    Ma Lai-Peng    Lichang Yin    Ma Teng    Zhiyong Zhang    Xiuliang Ma    彭练矛    成会明     任文才   

Nature Communications

2015

Wehave prepared flexible free-standing electrodes with anode and cathode active materials deposited on a highly conductive graphene membrane by a two-step filtration method. Compared with conventional electrodes using metal as current collectors, these electrodes have displayed stronger adhesion, superior electrochemical performance, higher energy density, and better flexibility. A full lithium ion battery assembled by adopting these graphene-based electrodes has showed high rate capability and long cyclic life.Wehave also assembled a thin, lightweight, and flexible lithium ion battery with poly-(dimethyl siloxane) sheets as packaging material to light a red light-emitting diode. This flexible battery can be easily bent without structural failure or performance loss and operated well under a bent state. The fabrication process of these graphene-based integrated electrodes only has two filtration steps; thus it is easy to scale up. These results suggest great potential for these graphene-based flexible batteries in lightweight, bendable, and wearable electronic devices.

Shi Ying    Wen Lei    Guangmin Zhou    Chen Jing    Pei Songfeng    Huang Kun    成会明     Feng Li   

2D Materials

2015

Transition metal carbides (TMCs) are a large family of materials with many intriguing properties and applications, and high-quality 2D TMCs are essential for investigating new physics and properties in the 2D limit. However, the 2D TMCs obtained so far are chemically functionalized, defective nanosheets having maximum lateral dimensions of ∼10μm. Here we report the fabrication of large-area high-quality 2D ultrathin α-MoC crystals by chemical vapour deposition (CVD). The crystals are a few nanometres thick, over 100 μm in size, and very stable under ambient conditions. They show 2D characteristics of superconducting transitions that are consistent with Berezinskii-Kosterlitz-Thouless behaviour and show strong anisotropy with magnetic field orientation; moreover, the superconductivity is also strongly dependent on the crystal thickness. Our versatile CVD process allows the fabrication of other high-quality 2D TMC crystals, such as ultrathin WC and TaC crystals, which further expand the large family of 2D materials.

Xu Chuan    Wang    Zhibo Liu    Chen Long    Guo Jingkun    Kang Ning    Xiuliang Ma    成会明     Ren Wencai   

Nature Materials

2015

A nitrogen-doped mesoporous carbon containing a network of carbon nanotubes (CNTs) was produced for use as a catalyst for the oxygen reduction reaction (ORR). SiO nanoparticles were decorated with clusters of Fe atoms to act as catalyst seeds for CNT growth, after which the material was impregnated with aniline. After polymerization of the aniline, the material was pyrolysed and the SiO was removed by acid treatment. The resulting carbon-based hybrid also contained some Fe from the CNT growth catalyst and was doped with N from the aniline. The Fe-N species act as active catalytic sites and the CNT network enables efficient electron transport in the material. Mesopores left by the removal of the SiO template provide short transport pathways and easy access to ions. As a result, the catalyst showed not only excellent ORR activity, with 59 mV more positive onset potential and 30 mV more positive half-wave potential than a Pt/C catalyst, but also much longer durability and stronger tolerance to methanol crossover than a Pt/C catalyst.

Li Jin-Cheng    Zhao Shi-Yong    Pengxiang Hou    Ruopian Fang    Chang Liu    Ji Liang    Luan Jian    Shan Xuyi    成会明    

Nanoscale

2015