Hydrogen generation from ammonia borane hydrolysis catalyzed by ruthenium nanoparticles supported on Co–Ni layered double oxides

Abstract

It is a very challenging task to develop high-performance metal catalysts for hydrolytic dehydrogenation of ammonia borane (AB, NH₃BH₃). In this work, cobalt–nickel layered double oxide (CoNi-LDO) with a sea urchin-like structure is prepared through the calcination of its corresponding layered double hydroxide (CoNi-LDH). As a catalyst support, ruthenium nanoparticles are loaded on CoNi-LDO by chemical reduction to form Ru/LDO catalysts. The effect of the reduction method (i.e., liquid-phase reduction and gas-phase reduction) and the auxiliary reagent citric acid (CA) on their catalytic properties for hydrogen production from AB hydrolysis is systematically studied. It takes only about 85 s at room temperature for the completion of AB hydrolysis in the presence of the as-prepared Ru-CA/LDO-G catalyst, which exhibits a much lower activation energy (E_a = 25.94 kJ mol⁻¹) and relatively higher activity (TOF = 501.4 mol_H2 mol_Ru⁻¹ min⁻¹). These experimental results are further confirmed by theoretical calculations, during which there is strong adsorption of AB molecules and easy activation of water molecules on Ru/LDO-G. Therefore, Ru/CoNi-LDO as a catalyst exhibits potential application in the field of hydrogen evolution from hydrolysis of hydroborates such as AB and NaBH₄.