Electron-deficient Co₇Fe₃ induced by interfacial effect of molybdenum carbide boosting oxygen evolution reaction

Developing a high-activity and low-cost catalyst to reduce the anodic overpotential is essential for hydrogen production from water splitting. In this work, a hetero-structured Co₇Fe₃/Mo₂C@C catalyst has been developed to efficiently catalyze oxygen evolution reaction (OER), the overpotential (ƞ₁₀) of Co₇Fe₃/Mo₂C@C-catalyzed OER with current density of 10 mA/cm² is about 254 mV, substantially lower than the counterparts of Co₇Fe₃@C-catalyzed OER (ƞ₁₀, 308 mV) and Mo₂C@C-catalyzed OER (ƞ₁₀, 439 mV), close to that of OER catalyzed by commercial RuO₂. The mechanistic studies reveal that the distinct electron transfer across the Co₇Fe₃/Mo₂C interface results in electron-deficient Co₇Fe₃, which has been identified as the highly active catalytic sites. Density functional theory (DFT) calculations manifest that Mo₂C induces a distinct decrease in electron density on Co₇Fe₃ and upgrades the d-band centers of Co and Fe in Co₇Fe₃ towards Fermi energy level, thus substantially lowering the energy barrier of the rate-determining reaction step and conferring significantly improved OER activity on the Co₇Fe₃/Mo₂C@C catalyst.