Synchronous Growth of Porous MgO and Half-Embedded Nano-Ru on a Mg Plate: A Monolithic Catalyst for Fast Hydrogen Production

Abstract

Development of efficient and sustainable monolithic catalysts for NaBH4 hydrolysis remains an important goal for hydrogen cycling. In this work, the structured catalyst Ru/MgO with an on–off feature has been prepared by directly growing a nano-Ru-embedded MgO coating layer on a Mg substrate via an instant high-temperature plasma oxidation process. The porous MgO framework provides an ideal space for the access of reactants and diffusion of mass transport, which facilitates reaction triggering and the expulsion of byproducts to avoid poisoning the catalyst. Importantly, Ru nanoparticles (NPs) are monodisperse with ultrasmall particle size deriving from a concurrent rapid arcing and fast quenching. The hierarchical structured Ru NP catalysts are highly active for hydrolysis of sodium borohydride by achieving a high hydrogen generation rate (HGR) of 101,189 mL min–1 g–1 and exhibit attractive stability. In addition, it is facile to realize the “on–off” functionality based on simple separation that could accurately control the hydrogen generation, suggesting the structured catalyst to be of great potential for practical applications. This simple method opens valuable opportunities for fast synthesis of the high-quality structured catalyst and could be extended to various noble metals on oxides of valve metals with high catalytic performance.