Tungsten doped FeCoP₂ nanoparticles embedded into carbon for highly efficient oxygen evolution reaction

Designing active and stable electrocatalysts with economic efficiency for oxygen evolution reaction (OER) is essential for developing water splitting process at an industrial scale. Herein, we rationally designed a tungsten doped iron cobalt phosphide incorporated with carbon (W_x-FeCoP₂/C), prepared by a mechanochemical approach. X-ray photoelectron spectroscopy (XPS) revealed that the doping of W led to an increasing of Co³⁺/Co²⁺ and Fe³⁺/Fe²⁺ molar ratios, which contributed to the enhanced OER performance. As a result, a current density of 10 mA cm^-2 was achieved in 1 M KOH at an overpotential of 264 mV on the optimized W_0.1-FeCoP₂/C. Moreover, at high current density of 100 mA cm^-2, the overpotential value was 310 mV, and the corresponding Tafel slope was measured to be 48.5 mV dec^-1, placing it among the best phosphide-based catalysts for OER. This work is expected to enlighten the design strategy of highly efficient phosphide-based OER catalysts.