Preparation and characterization of nanostructured Co-Mo-B thin film catalysts for the hydrolysis of ammonia borane

Nanostructured Co-Mo-B thin film catalysts were prepared via electroless plating method on the foam sponge. The effect of depositional pH value on the hydrogen generation rate from the hydrolysis of ammonia borane was investigated. The results show that the hydrogen generation rate increases from 3890.9 to 5100.0 mL min(-1) g(cat)(-1), when the pH value increases from 10.5 to 11.0. However, the hydrogen generation rate reduces to 3945.5 and 3242.3 mL min(-1) g(cat)(-1), when the pH value further increases to 11.5 and 12.0, respectively. Hence, it can be seen that the as-prepared Co-Mo-B thin film catalyst (pH = 11.0) exhibits the highest hydrogen generation rate, which could be attributed to the smaller size and the synergistic effect of Co, Mo and B on the catalyst surface. Moreover, the activation energy of the catalytic hydrolysis reaction at 298 K was 41.7 kJ mol(-1). The value is lower than that of the most of Ni-based and Co-based catalysts, even some noble metal catalysts. After 5 cycles, the catalytic activity of the Co-Mo-B thin film catalyst remains about 61.9% of its initial value. Based on the SEM analysis, the reduction of the catalytic activity could be ascribed to the agglomeration of the active substance and some impurity phase on the catalyst surface. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.