Xue Sun,Fang Li,Zhimiao Wang,Hualiang An,Wei Xue,Xinqiang Zhao,Yanji Wang
Well-dispersed AuPd nanoparticles were immobilized on TiO 2 -NC supports derived from NH 2 -MIL-125(Ti) and used as highly active, stable catalysts for hydrogen production from formic acid under mild conditions. The highest total turnover frequency , i.e., 3207 h −1 , for formic acid dehydrogenation was achieved with Au 2 Pd 8 /TiO 2 -NC-800 as the catalyst at 60 °C; this is 1.4 times that achieved with Au 2 Pd 8 /TiO 2 –C-800 under the same conditions. The excellent performance of the Au 2 Pd 8 /TiO 2 -NC-800 catalyst originates from the high anatase TiO 2 content, pyridinic N and oxygen vacancies in the support, the small size and alloying effect of the AuPd nanoparticles, and the metal–support synergistic effect . Doping the support with N improves the catalyst stability because N prevents metal particle aggregation to some extent. These results provide guidelines for the future development and applications of catalysts based on TiO 2 and metal–organic-framework-derived carbon-based materials.
The core-shell structural N-doped carbon encapsulating Si@TiO 2 composite (Si@TiO 2 /NC) are prepared by facile sol-gel, polymerization of dopamine hydrochloride and the following heat treatment processes, which are confirmed by the scanning electron microscopy, X-ray diffractometer, transmission electron microscopy , X-ray photoelectron spectroscopy and thermogravimetric analyses. The as-prepared Si@TiO 2 /NC composite present favorable spherical shape with about 150 nm in diameter and uniform element distribution, and demonstrate the enhanced electrochemical properties compared to the pure silicon , Si@TiO 2 and Si/NC materials when the composite materials are used as anodes for lithium-ion batteries, in which the Si@TiO 2 /NC composite anodes display the favorable initial coulombic efficiency of 75.9%, remarkable charge specific capacity of 1070.9 mAh g −1 with the coulombic efficiency approaching 100% after 100 cycles under the test current of 200 mA g −1 , extraordinary rate and cycle capability with the charge specific capacity of 696.2 mAh g −1 under the test current of 3000 mA g −1 and increased lithium ion diffusion coefficient from 8.179 E-12 cm 2 s −1 to 8.995 E-12 cm 2 s −1 after 100 cycles. Those excellent electrochemical properties can be attributed to the synergistic effect of the robust TiO 2 skeleton and the elastic conductive N-doped carbon network, indicating the as-prepared Si@TiO 2 /NC composite could be a promising anode for lithium-ion batteries.
危险品化学品经营许可证（带存储）