A Ru–MoC heterostructure electrocatalyst for efficient and stable hydrogen oxidation reaction in alkaline media

Abstract

Owing to its higher oxophilicity and similar hydrogen adsorption strength to Pt, Ru has been regarded as a promising alternative to overcome sluggish hydrogen oxidation reaction (HOR) kinetics in alkaline media. However, the strong oxophilicity of Ru also results in insufficient hydrogen adsorption sites on Ru catalysts and poor stability. Herein, a rationally designed Ru-based heterostructure catalyst with abundant Ru and MoC interfaces (Ru–MoC/C) was prepared. Ru–MoC/C exhibits great stability and excellent mass activity (1.74 mA μg_PGM⁻¹), which is approximately 4 and 3 times greater than that of Ru/C and Pt/C, respectively. And Ru–MoC/C displays stable operation for 10000 s at 0.1 V versus the reversible hydrogen electrode (RHE) in a chronoamperometry test. Experimental results and theoretical simulations revealed that the electron transfer from Ru to MoC at heterostructure interfaces, driven by differences in work functions, causes the d band center of Ru in Ru–MoC/C to shift downward, thus weakening the hydrogen binding as well as hydroxyl binding at Ru sites. Meanwhile, the strongly oxophilic MoC can substitute Ru as a hydroxyl adsorption site, resulting in enhanced hydroxyl binding at the heterostructure interfaces. Consequently, these factors synergistically accelerate the HOR kinetics on Ru–MoC/C and promote the stability of Ru–MoC/C.