原位合成钴/还原氧化石墨烯纳米粒子催化氨硼烷制氢

采用简单的原位还原合成方法，利用具有温和还原性能的氨硼烷作为还原剂，在室温下一步还原氧化石墨烯和氯化钴混合溶液制备了还原氧化石墨烯负载钴纳米复合材料催化剂. 利用所制备的钴/还原氧化石墨烯催化剂催化氨硼烷水解制氢，发现钴/还原氧化石墨烯具有优异的催化性能. 相对于没有负载的钴纳米粒子以及采用硼氢化钠作为还原剂制备的钴/还原氧化石墨烯催化剂，采用氨硼烷还原制备的钴/还原氧化石墨烯催化剂表现出更加优越的催化性能. 动力学测试表明，钴/还原氧化石墨烯催化氨硼烷水解反应为零级反应，同时钴/还原氧化石墨烯催化剂催化氨硼烷水解反应的活化能为27.10 kJ·mol^-1，低于大部分已报道的其它催化剂,甚至一些贵金属催化剂的活化能. 钴/还原氧化石墨烯催化剂有着稳定的循环使用性，特别是其具有的磁性使得它能够直接从溶液中通过磁力回收，极具应用前景. 这种简单有效的合成方法有望推广到其它的金属-还原氧化石墨烯纳米复合材料体系.

In situ Synthesis of Reduced Graphene Oxide Supported Co Nanoparticles as Efficient Catalysts for Hydrogen Generation from NH3BH3

Cobalt nanoparticles (NPs) supported on reduced graphene oxide (RGO) were synthesized by a one-step in situ co-reduction of an aqueous solution of cobalt(Ⅱ) chloride and graphene oxide (GO) using ammonia borane (AB) as the sole reductant under ambient conditions. The as-synthesized Co/RGO catalysts exhibited high catalytic activity for the hydrolytic dehydrogenation of AB at room temperature. The assynthesized Co/RGO nanocatalysts exhibited much higher catalytic activity than the RGO-free Co counterpart. Compared with the nanocatalysts reduced by NaBH4, the Co/RGO nanocatalysts generated by the milder reductant AB exhibited superior catalytic activity. Moreover, kinetic studies indicate that the catalytic hydrolysis of AB by Co/RGO has zero order kinetics with respect to the substrate concentration. The hydrolysis activation energy is estimated to be about 27.10 kJ·mol^-1, which is lower than most reported data for the same reaction conusing non-noble metal catalysts and some noble metal containing catalysts. Furthermore, the RGO-supported Co NPs show good recyclability and magnetic reusability for hydrogen generation from an aqueous solution of AB, which enables the practical reuse of the catalysts. Hence, this general method indicates that AB can be used as both a potential hydrogen storage material and an efficient reducing agent, and can be easily extended to the facile preparation of other RGO-based metallic systems.