Construction of Mo-CoNiFe-S/NF and Its Outstanding Electrocatalytic Performance in the Oxygen Evolution Reaction

While molybdenum (Mo)-doped catalysts exhibit excellent hydrogen evolution reaction (HER) performance, their oxygen evolution reaction (OER) efficiency is limited by high overpotentials. To address the restricted OER efficiency caused by elevated overpotentials, this study develops a Mo-doped CoNiFe-S electrocatalyst on nickel foam (NF) through sequential electrodeposition of CoNiFe-LDH followed by hydrothermal sulfidation, with elemental Mo doped via electrodeposition. The optimized Mo-CoNiFe-S/NF achieves a record-low overpotential of 69 mV at 10 mA cm⁻² and Tafel slope of 78.4 mV dec⁻¹, outperforming > 95% of reported transition metal-based catalysts. This enhancement originates from sulfidation-induced synergistic electronic modulation between Mo and CoNiFe, which: (1) forming a flake-like layered structure to increase active sites and (2) enhances intrinsic OER activity. This work provides a novel strategy for designing efficient non-precious electrocatalysts by coupling heteroatom doping with sulfidation engineering.