Mingzhong Zou(邹明忠，硕士生), Jiaxin Li(李加新，博士生), WeiWei Wen(温伟伟，硕士生), Luzhuo Chen(陈鲁倬), Lunhui Guan(官轮辉), Heng Lai(赖恒), Zhigao Huang(黄志高),Silver-incorporated composites of Fe2O3 carbon nanofibers as anodes for high-performance lithium batteries, Journal of Power Sources, Volume 270, 15 December 2014, Pages 468-474.
Composites of Ag-incorporated carbon nanofibers (CNFs) confined with Fe2O3 nanoparticles (Ag–Fe2O3/CNFs) have been synthesized through an electrospinning method and evaluated as anodes for lithium batteries (LIBs). The obtained Ag–Fe2O3/CNF anodes show good LIB performance with a capacity of 630 mAh g−1 tested at 800 mA g−1 after 150 cycles with almost no capacity loss and superb rate performance. The obtained properties for Ag–Fe2O3/CNF anodes are much better than Fe2O3/CNF anodes without Ag-incorporating. In addition, the low-temperature LIB performances for Ag–Fe2O3/CNF anodes have been investigated for revealing the enhanced mechanism of Ag-incorporating. The superior electrochemical performances of the Ag–Fe2O3/CNFs are associated with a synergistic effect of the CNF matrix and the highly conducting Ag incorporating. This unique configuration not only facilitates electron conduction especially at a relative temperature, but also maintains the structural integrity of active materials. Meanwhile, the related analysis of the AC impedance spectroscopy and the corresponding hypothesis for DC impedance confirm that such configuration can effectively enhance the charge-transfer efficiency and the lithium diffusion coefficient. Therefore, CNF-supported coupled with Ag incorporating synthesis supplied a promising route to obtain Fe2O3 based anodes with high-performance LIBs especially at low temperature.
Mingzhong Zou(邹明忠，硕士生), Weiwei Wen(温伟伟，硕士生), Jiaxin Li(李加新，博士生), Yingbin Lin(林应斌), Heng Lai(赖恒), Zhigao Huang(黄志高), Nano-crystalline FeOOH mixed with SWNT matrix as a superior anode material for lithium batteries, Journal of Energy Chemistry, Volume 23, Issue 4, July 2014, Pages 513–518.
Nano-crystalline FeOOH particles (5∼10 nm) have been uniformly mixed with electric matrix of single-walled carbon nanotubes (SWNTs) for forming FeOOH/SWNT composite via a facile ultrasonication method. Directly using the FeOOH/SWNT composite (containing 15 wt% SWNTs) as anode material for lithium battery enhances kinetics of the Li+ insertion/extraction processes, thereby effectively improving reversible capacity and cycle performance, which delivers a high reversible capacity of 758 mAh•g−1 under a current density of 400 mA•g−1 even after 180 cycles, being comparable with previous reports in terms of electrochemical performance for FeOOH anode. The good electrochemical performance should be ascribed to the small particle size and nano-crystalline of FeOOH, as well as the good electronic conductivity of SWNT matrix.
Jian-Min Zhang(张健敏), Zhigao Chen(陈志高), Kehua Zhong(钟克华，博士生), Guigui Xu(许桂贵), Zhigao Huang(黄志高), Hydrogen induced room-temperature ferromagnetism in Co-doped ZnO: first-principles and Monte Carlo study, Chinese Science Bulletin, September 2014, Volume 59, Issue 26, pp 3232-3238.
The structural stability, vibrational and magnetic properties of hydrogen doped ZnO:Co have been studied by first-principles calculations based on density functional theory. Bond-center (BC) sites were identified to be most stable sites for hydrogen, the corresponding vibrational frequencies including anharmonic contributions were calculated. Its magnetic properties were investigated as well. The calculated results reveal that hydrogen could induce the change of electronic transfer, leading to a decrease of magnetic moment. However, the magnetic coupling between Co atoms is greatly strengthen. The results simulated by Monte Carlo method indicate that hydrogen can induce the Curie temperature to increase from 200 to 300 K.
Kehua Zhong(钟克华，博士生), Guigui Xu(许桂贵), Yanmin Cheng(程燕铭，硕士生), Keqin Tang(汤可嵚，硕士生), Zhigao Chen(陈志高), Zhigao Huang(黄志高), Spin and surface orientation effects of work function for Cr/Ni(111), Cr/Ni(100) and Cr/Ni(110) metal gates, International Journal of Modern Physics B, Volume 28, Issue 24, 30 September 2014.
Work functions of Cr/Ni(111), Cr/Ni(100) and Cr/Ni(110) surfaces with different magnetic configurations for Cr atoms in the topmost Cr monolayer are investigated using first-principles methods based on density functional theory. The calculated results reveal that work functions vary with crystal orientations and magnetic configurations. The magnitude of the Cr magnetic moments for the three (111), (100) and (110) surfaces follows a change trend with MCr, Cr/Ni(111) < MCr, Cr/Ni(100) < MCr, Cr/Ni(110). Altering the magnetic configurations of the systems from an original ground state to an excited one will have the total energy and the Fermi level increase. Consequently, it will give rise to the reduction of the work function for the system. Moreover, the quite favorable variation range (4.92–4.41 eV) of the calculated work functions for Cr/Ni(100) system modulated by spin effect implies that the Cr/Ni(100) system may be a more promising candidate. Our work suggests that changing magnetic configurations can modulate the work functions of magnetic metal gates well.