Mo modulation effect on the hydrogen binding energy of hexagonal-close-packed Ru for hydrogen evolution

As a cheaper Pt-group metal, ruthenium (Ru) is a highly competitive alternative to Pt for commercialization towards the hydrogen evolution reaction (HER). Herein, we report the modulation effect on the Gibbs free energy (ΔGH*) of hexagonal-close-packed (hcp) Ru resulting from heteroatom Mo doping. In particular, for the first time the hcp MoRu3 crystal structure is theoretically predicted with pretty high intrinsic HER activity. Meanwhile, the Mo hetero-dopant could act as a new active site with Pt-like ΔGH*. Motivated by the prediction, we report a novel metal organic framework (MOF)-assisted synthetic strategy to prepare a Mo-doped hcp Ru electrocatalyst. Accordingly, the hcp MoRu3 catalyst exhibits an ultralow overpotential of 30.5 mV at 10 mA cm−2, ensuring excellent Pt-like intrinsic HER activity. More importantly, the excellent electrochemical performance measured with a proton exchange membrane (PEM) electrolyzer further highlights the promising potential of the hcp MoRu3 catalyst for hydrogen production.