Synergetic Oxidized Mg and Mo Sites on Amorphous Ru Metallene Boost Hydrogen Evolution Electrocatalysis

Ruthenium (Ru) is considered as a promising catalyst for the alkaline hydrogen evolution reaction (HER), yet its weak water adsorption ability hinders the water splitting efficiency. Herein, a concept of introducing the oxygenophilic MgOx and MoOy species onto amorphous Ru metallene is demonstrated through a simple one-pot salt-templating method for the synergic promotion of water adsorption and splitting to greatly enhance the alkaline HER electrocatalysis. The atomically thin MgOx and MoOy species on Ru metallene (MgOx/MoOy-Ru) show a 15.3-fold increase in mass activity for HER at the potential of 100 mV than that of Ru metallene and an ultralow overpotential of 8.5 mV at a current density of 10 mA cm-2. It is further demonstrated that the MgOx/MoOy-Ru-based anion exchange membrane water electrolyzer can achieve a high current density of 100 mA cm-2 at a remarkably low cell voltage of 1.55 V, and exhibit excellent durability of over 60 h at a current density of 500 mA cm-2. In situ spectroscopy and theoretical simulations reveal that the co-introduction of MgOx and MoOy enhances interfacial water adsorption and splitting by promoting adsorption on oxidized Mg sites and lowering the dissociation energy barrier on oxidized Mo sites.