Efficient Co-Nanocrystal-Based Catalyst for Hydrogen Generation from Borohydride

Sodium borohydride (NaBH 4 ) has been proposed as a potential hydrogen storage material for fuel cells, and the development of highly active and robust catalysts for hydrolyzing NaBH 4 is the key for the practical usage of NaBH 4 for fuel cells. Herein we report Co-nanocrystal assembled hollow nanoparticles (Co-HNP) as an active and robust catalyst for the hydrolysis of NaBH 4 . A hydrogen generation rate of 10.8 L·min –1 ·g –1 at 25 °C was achieved by using the Co-HNP catalyst with a low activation energy of 23.7 kJ·mol –1, which is among the best performance of reported noble and non-noble catalysts for hydrolyzing NaBH 4 . Co-HNP also showed good stability in the long term cycling tests. The mechanism of the catalytic hydrolysis of NaBH 4 on Co-HNP was studied by using 1 H and 11 B solid-state NMR, which provided unambiguous experimental evidence of the Co–H formation. The systematically designed NMR experiments unveiled the key role of Co-HNP in the activation of borohydride and the subsequent transfer of H – to water for generating H 2 gas and helped to distinguish various hypotheses proposed for catalytic H 2 generation reactions. The porous hollow nanostructure of the Co-HNP catalyst provides large surface area and facilitates mass transfer. The facile preparation and outstanding performance of Co-HNP enables it as a very competitive catalyst for hydrogen production.