Exposed Facet Tailoring of Ni/Cu Catalysts for Boosting Dehydrogenation of Ammonia Borane

Abstract

The design of efficient and inexpensive nanocatalysts for the room-temperature hydrolysis of ammonia borane (AB) is important for its practical application in hydrogen (H 2 )based fuel cells. In this study, Cu micron-crystals with different exposed crystal facets are successfully prepared by a pseudomorphic conversion process. Ni/Cu catalysts are synthesized through an in situ one-pot liquid reaction method by applying these Cu micrometer crystals as supports. Contrastive studies demonstrate the obviously close correlativity between catalytic capacity and the crystal facets for Ni/Cu catalysts, but not for the pure Cu or Cu 2 O catalysts. The Ni/Cu cubes with (100) facets exposed deliver a markedly enhanced effect in AB dehydrogenation compared to truncated octahedra and octahedra with less (100) facets. The superior catalytic activity of Ni/Cu cubes can be attributed to their capacity to dissociatively adsorb H 2 O and AB molecules on Ni/ Cu(100) surface, which is supported by the results of first-principle calculations. Furthermore, the cycling performance is investigated, and Ni/Cu cubes have been found to have a superior performance. This research could lead to further exploration of the facet effect toward rational design of catalysts for AB dehydrogenation.