Atomically Dispersed Pt on the Surface of Ni Particles: Synthesis and Catalytic Function in Hydrogen Generation from Aqueous Ammonia–Borane

The development of cost-effective and highly efficient catalysts is of scientific importance and practical need in the conversion and utilization of clean energy. One of the strategies fulfilling that demand is to achieve high exposure of a catalytically functional noble metal to reactants to maximize its utilization efficiency. We report herein that the single-atom alloy (SAA) made of atomically dispersed Pt on the surface of Ni particles (Pt is surrounded by Ni atoms) exhibits improved catalytic activity on the hydrolytic dehydrogenation of ammonia–borane, a promising hydrogen storage method for onboard applications. Specifically, an addition of 160 ppm of Pt leads to ca. 3-fold activity improvement in comparison to that of pristine Ni/CNT catalyst. The turnover frequency based on the isolated Pt is 12000 mol_H2 mol_Pt^–1 min^–1, which is about 21 times the value of the best Pt-based catalyst ever reported. Our simulation results indicate that the high activity achieved stems from the synergistic effect between Pt and Ni, where the negatively charged Pt (Pt^δ‑) and positively charged Ni (Ni^δ+) in the Pt-Ni alloy are prone to interact with H and OH of H₂O molecules, respectively, leading to an energetically favorable reaction pathway.