Ni nanoparticles supported on CNTs with excellent activity produced by atomic layer deposition for hydrogen generation from the hydrolysis of ammonia borane

Highly dispersed, uniform Ni nanoparticles with controlled loadings supported on multi-walled carbon nanotubes (CNTs) were synthesized by atomic layer deposition for hydrogen generation from the hydrolysis of ammonia borane (AB). The catalytic performance of Ni/CNT nanocatalysts prepared with varying ALD cycle numbers was investigated for the hydrolysis of AB in water. The results show that all the Ni/CNT nanocatalysts exhibit excellent catalytic activities towards the hydrolysis of AB, and the Ni/CNTs produced with 200 ALD cycles have the highest hydrogen generation rate, with a total turnover frequency value as high as 26.2 mol_H2 mol_Ni^-1 min^-1, which is higher than that of most nickel-based catalysts previously reported in the literature. The hydrolysis completion time and activation energy of AB hydrolysis are 4.5 min and 32.3 kJ mol^-1, respectively. Furthermore, 2 ALD cycles of Pt doping (only 0.68 wt%) can significantly improve the catalytic activity and reusability of Ni/CNT nanocatalysts due to its promotion effect. Our results suggest that ALD is a promising technique for designing and fabricating efficient, economical, and non-noble metal nanocatalysts for the hydrolysis of AB.