Novel Ni-Co-B hollow nanospheres promote hydrogen generation from the hydrolysis of sodium borohydride

Ni-Co-B hollow nanospheres were synthesized by the galvanic replacement reaction using a Co-B amorphous alloy and a NiCl2 solution as the template and additional reagent, respectively. The Ni-Co-B hollow nanospheres that were synthesized in 60 min (Ni-Co- B-60) showed the best catalytic activity at 303 K, with a hydrogen production rate of 6400 ML(hydrogen)min(-1)g(-)1(catalyst) and activation energy of 33.1 kJ/mol for the NaBH4 hydrolysis reaction. The high catalytic activity was attributed to the high surface area of the hollow structure and the electronic effect. The transfer of an electron from B to Co resulted in higher electron density at Co sites. It was also found that Ni was dispersed on the Co-B alloy surface as result of the galvanic replacement reaction. This, in turn, facilitated an efficient hydrolysis reaction to enhance the hydrogen production rate. The parameters that influenced the hydrolysis of NaBH4 over Ni-Co-B hollow nanospheres (e.g., NaOH concentration, reaction temperature, and catalyst loading) were investigated. The reusability test results show that the catalyst is active, even after the fifth run. Thus, the Ni-Co-B hollow nanospheres are a practical material for the generation of hydrogen from chemical hydrides. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.