A stable and efficient 3D cobalt-graphene composite catalyst for the hydrolysis of ammonia borane

Abstract

Low-cost, stable and highly efficient catalysts are essential for practical energy applications. In this study, branched polyethylenimine (PEI)-decorated graphene oxide (GO) 3D structures were prepared through a hydrothermal reaction. Cobalt (Co) nanoparticles (NPs) were deposited on the PEI-GO 3D structures, forming the desired, low-cost composite catalyst PEI–GO_3D/Co. The catalyst shows a quite high catalytic activity for the room temperature hydrolysis of ammonia borane, with a turnover frequency of 18.5 mol_H2 min⁻¹ mol_Co⁻¹ and a hydrogen generation rate of 7.68 L_H2 min⁻¹ g_Co⁻¹. The activation energy of the catalyst is relatively low (27.41 kJ mol⁻¹), along with an ultrahigh cycle stability, that is, ∼83% of the initial catalytic activity was retained after 5 catalytic cycles, superior to the majority of non-noble metal catalysts.