PtNi/NiO Clusters Coated by Hollow Sillica: Novel Design for Highly Efficient Hydrogen Production from Ammonia-Borane

Ammonia borane (NH3.BH3; AB) has been considered as an excellent chemical material for hydrogen storage. However, developing highly efficient catalysts for continuous hydrogen generation from AB is still a challenge for future fuel cell applications. The combination of Pt with Ni is an effective strategy to achieve active bimetallic nanocatalyst, and the particle size has proved to play a crucial role in determining its final activity. However, the synthesis of PtNi bimetallic catalyst in the size of highly dispersed clusters has always been a challenge. In this report, PtNi/NiO clusters coated by small-sized hollow silica (R-PtNi/NiO@SiO2) were designed for efficient hydrogen generation from the hydrolysis of ammonia borane. The newly designed catalysis system showed extremely high activity with the initial turnover frequency value reaching 1240.3 mol of H-2.mol(-1) of Pt.min(-1), which makes it one the most active Pt-based catalysts for this reaction. Detailed characterization by means of scanning transmission electron microscopy, X-ray photoelectron spectroscopy, energy-dispersive Xray spectroscopy element mapping, etc. revealed that the excellent performance of R-PtNi/NiO@SiO2, is derived from the highly dispersed PtNi/NiO clusters and the reduction of extra Pt4+ on the surface of PtNi/NiO clusters to Pt at relatively low temperature.