Supported rhodium catalysts for ammonia-borane hydrolysis. Dependence of the catalytic activity on the highest occupied state of the single rhodium atoms

Supported metal nanocrystals have exhibited remarkable catalytic performance in hydrogen generation reactions, which is influenced and even determined by their supports. Accordingly, it is of fundamental importance to determine the direct relationship between catalytic performance and metal-support interactions. Herein, we provide a quantitative profile for exploring metal-support interactions by considering the highest occupied state in single-atom catalysts. The catalyst studied consisted of isolated Rh atoms dispersed on the surface of VO₂ nanorods. It was observed that the activation energy of ammonia-borane hydrolysis changed when the substrate underwent a phase transition. Mechanistic studies indicate that the catalytic performance depended directly on the highest occupied state of the single Rh atoms, which was determined by the band structure of the substrates. Other metal catalysts, even with non-noble metals, that exhibited significant catalytic activity towards NH₃BH₃ hydrolysis were rationally designed by adjusting their highest occupied states. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)