Rapid synthesis of an OER catalytic surface on dual-phase high-entropy alloys via a controllable single-phase corrosion approach

High-entropy alloys (HEAs) are considered to be promising multifunctional electrocatalysts because of their diverse constituent elements, structural uniformity, and multiple active sites that can be applicable for various reactions. In this study, the Fe20Co20Ni20Cr20Mo20 HEA was utilized as a substrate to rapidly synthesize a nanostructured porous film with a highly active HEA surface area via an electrochemical one-step dealloying method. The dealloyed HEA exhibited an excellent oxygen evolution activity, with a low overpotential of only 370 mV at 40 mA cm−2, which is lower than those of the commercial IrO2–RuO2–Ta2O5/Ti (500 mV) and IrO2–RuO2/Ti (542 mV) catalysts, and a Tafel slope of 119 mV dec−1. After synthesizing a nanostructured porous film through dealloying, the active surface area of the HEA increased by 30%. Following a 60-h stability test, the overpotential difference of the HEA before and after the stability test is less than 30 mV, signifying outstanding stability. The obtained results indicate that the prepared FeCoNiCrMo HEA is primarily composed of two phases, namely the σ phase and the face-centered cubic (FCC) phase. The uneven distribution of the corrosion-resistant element Cr in these phases resulted in significantly different corrosion rates for the two phases, wherein the FCC phase underwent preferential corrosion. Additionally, synergistic electronic coupling among the surface atoms of the nanostructured porous film further enhanced the oxygen evolution reaction (OER) performance. This electrochemical dealloying method demonstrated a high reproducibility and provided an effective pathway for optimizing OER catalysts.