Mo vacancies enhancing Pt, Ni co-incorporated Mo2C nanofibers for high-efficiency water decomposition

Abstract

Hard alloy type compounds are promising candidates for developing robust and cost-effective electrocatalysts due to the good conductivity and lattice hardness. However, their insufficient intrinsic activities require further surface modification, which remains a significant challenge due to the high hardness and surface inertness. Herein, a vacancies-promoted heteroatoms integration method is provided to construct Pt and Ni co-incorporated molybdenum carbide nanofibers ((Pt, Ni)-Mo₂C). The Pt and Ni atoms filling into the Mo vacancy reduce the formation energy by ∼5.5 eV, which indicates an improved crystal stability. The electrons flow from Mo, Ni centers to Pt, C centers, resulting in the shifted average valence of Mo, Ni sites and moderate oxidation states of Pt, C sites. Therefore, the hydrogen adsorption free energy (ΔG_∗H) of Mo and C sites increases from ∼-0.6 eV to ∼-0.03 eV (C sites) and ∼-0.2 eV (Mo sites), resulting in a state closer to ideal state (0 eV). As a result, the (Pt, Ni)-Mo₂C catalyst exhibits an excellent overpotential of 64 mV at 10 mA cm⁻² for hydrogen evolution reaction (HER), reducing by 149 mV than pure Mo₂C. Current work paves a favorable method for integrating dissimilar atoms to modify hard alloy type compound surface.