Kinetically promoted hydrogen generation by Ru nanoparticles decorated CoB2O4 on mesoporous carbon spheres with rich oxygen vacancies for NaBH4 hydrolysis

Abstract

Developing heterostructured catalysts with highly active and reusable is an urgent task to achieve green hydrogen production via NaBH4. Herein, we proposed a novel NaCl template method, which involves solid-state physical grinding of metal salts, reducing agents and prepared carbon spheres with the participation of sodium chloride to synthesize Ru-particles decorated CoB2O4 supported on hollow mesoporous carbon nanospheres (Ru/CoB2O4@C) catalysts for efficient and durable H2 generation through alkaline hydrolysis of NaBH4. The optimized catalyst with a Ru content of 3.0 wt% exhibits a high hydrogen generation rate of 8139 mL min−1gcat-1 and a low activation energy of 33.2 kJ mol−1 for NaBH4 hydrolysis, which is one of the most efficient catalysts reported recently. The extraordinary performance is mainly attributed to the synergistic effect between Ru and CoB2O4 species and abundant oxygen vacancies, which facilitate charge redistribution and provide more active sites, thereby enhancing the catalytic activity. Density functional theory calculations support the proposed Michaelis-Menten mechanism, where BH4− and H2O are adsorbed on electron-rich Ru and electron-deficient CoB2O4 surfaces, respectively, and the reaction energy barrier for the rupture of the B-H bond as the rate-determining step is only 1.37 eV, synergistically promoting the hydrolysis of NaBH4. Our study provides an innovative method for designing efficient and stable catalysts for green hydrogen generation.