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 (ΔG _H∗ ) of hexagonal-close-packed (hcp) Ru resulting from heteroatom Mo doping. In particular, for the first time the hcp MoRu ₃ 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 ΔG _H∗ . 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 MoRu ₃ 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 MoRu ₃ catalyst for hydrogen production.