▎ 摘　　要

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 center dot mol(-1), which is lower than most reported data for the same reaction using 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.