Alloyed palladium-nickel hollow nanospheres with interatomic charge polarization for improved hydrolytic dehydrogenation of ammonia borane

Hydrolysis reaction of ammonia borane (AB) has been considered as a safe and efficient hydrogen generation method, in which designing cost-effective and high-performance catalysts plays vital role. In this work, we have developed well dispersed palladium-nickel hollow nanospheres (PdNi HNSs) with tunable shell thiclmess"and compositions via a facile galvanic replacement approach. The as-prepared PdNi HNSs show composition-dependent catalysis in the hydrolytic dehydrogenation of AB. The Pd84Ni16/C exhibiting sphere-shaped hollow interiors with average 70 nm particle size and 10 nm thin wall, presents the highest catalytic activity with the turnover frequency of 76.0 (mol H-2 min(-1) (mol Pd)(-1)) and the activation energy of 33.5 kJ ma(-1). The superior catalytic effect of PdNi HNSs in enhancing hydrolysis efficiency of AB can be ascribed to two major factors: (1) high active surface areas of the unique hollow structure; (2) enhanced H adsorption attributed to the coupling between Pd and Ni induces polarization charges on Pd catalytic sites, which is indicated by the first-principles calculation and X-ray photoelectron spectroscopy studies. Furthermore, the catalysts exert good long-term recycling stability and catalytic activity for the hydrolytic dehydrogenation of AB. This work represents a strategy may hopefully be extended to synthesize other Pd-based hollow nanostructure with reduced Pd usage and increased catalytic active sites, and also sheds light on the exploration of utilizing interatomic interactions to regulate species adsorption/activation for highly efficient catalytic performance. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.