Electron-deficient CoFe 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 CoFe/MoC@C catalyst has been developed to efficiently catalyze oxygen evolution reaction (OER), the overpotential (ƞ) of CoFe/MoC@C-catalyzed OER with current density of 10 mA/cm is about 254 mV, substantially lower than the counterparts of CoFe@C-catalyzed OER (ƞ, 308 mV) and MoC@C-catalyzed OER (ƞ, 439 mV), close to that of OER catalyzed by commercial RuO. The mechanistic studies reveal that the distinct electron transfer across the CoFe/MoC interface results in electron-deficient CoFe, which has been identified as the highly active catalytic sites. Density functional theory (DFT) calculations manifest that MoC induces a distinct decrease in electron density on CoFe and upgrades the d-band centers of Co and Fe in CoFe towards Fermi energy level, thus substantially lowering the energy barrier of the rate-determining reaction step and conferring significantly improved OER activity on the CoFe/MoC@C catalyst.