Boosting Alkaline Hydrogen Evolution on Stoichiometric Molybdenum Carbonitride via an Interstitial Vacancy-Elimination Strategy

An interstitial vacancy on molybdenum nitride has been determined as a negative factor towards the alkaline hydrogen evolution reaction (HER) by reason of upraising the d orbitals of Mo. Nevertheless, investigations aiming to eliminate the vacancies are rarely reported. Here, an interstitial reconfiguration method for the design of stoichiometric molybdenum carbonitride (Mo₂CN) is proposed, in which the vacancies are fulfilled by lattice carbon. Multiple fine structural analyses alongside with the theoretical calculations indicate that beyond lower the d orbitals of Mo by the hybridization of additive p-d orbitals, lattice carbon also behaves as the extra active center with exceptional H adsorption/desorption energy. Mo₂CN reveals an adorable overpotential of −84 mV at a current density of 10 mA cm⁻² with a long-term electrochemical stability by accompanying the nitrogen-doped carbon substrate. It is anticipated that the vacancy-eliminating concept will provide a constructive entry point for the rational design of electro-catalysts and beyond.