Carbon-supported Ni_3B nanoparticles as catalysts for hydrogen generation from hydrolysis of ammonia borane

摘要

We report the preparation of Ni_3B and carbon-supported Ni_3B (denoted as Ni_3B/C) nanoparticles, and their catalytic performance for hydrogen generation from hydrolytic dehy-drogenation of ammonia borane (NH_3BH_3, AB). Ni_3B and Ni_3B/C were prepared via a chemical reduction and crystallization in tetraethylene glycol solution. The obtained Ni_3B catalysts are in well-defined crystalline state and Ni_3B/C catalysts have a high dispersion in the carbon. The hydrogen generation measurement shows that the carbon-supported Ni_3B presents enhanced catalyst activity during hydrolytic dehydrogenation of AB. Among the as-prepared Ni_3B/C catalysts, Ni_3B/C with 34.25 wt% Ni_3B loading displays the best catalytic activity, delivering a high hydrogen release rate of 1168 mL min~ 1 g~ 1 and the lower activation energy of 46.27 kJ mol~1. The kinetic results show that the hydrolysis is a first-order reaction in catalyst concentration, while it is a zero-order in AB concentration. Furthermore, the Ni_3B/C is a recyclable catalyst under mild reaction conditions, indicating that the carbon-supported Ni_3B is a promising catalyst for AB hydrolytic dehydrogenation.