Cost‐Effective High Entropy Core–Shell Fiber for Stable Oxygen Evolution Reaction at 2 A cm−2

Abstract Exploring highly efficient oxygen evolution reaction (OER) electrocatalysts is important for industrial water electrolysis, especially under high current densities (>1 A cm −2 ). High‐entropy alloy (HEA) with high surface OER activity and excellent electrical conductivity of the core is an ideal route to improve the catalytic activity. Herein, a combined theoretical and experimental approach to establish core–shell FeCoNiMoAl‐based HEA as a promising OER electrocatalyst is presented. Theoretical calculations combined with structure analyses indicate crystalline–amorphous ( c–a ) heterostructure of shell reduces the electron transfer resistance and generates more active sites, furthermore the crystalline core improves the conductivity and self‐supporting ability. HEA electrodes demonstrate superior OER performance with an overpotential ( η ) of 470 mV at 2 A cm −2 and no apparent degradation even after 330 h of continuous testing, notably, for overall water splitting the stability is more than 120 h at 2.06 V. The special core–shell structure achieves a win–win strategy for high OER activity and stability. These findings shed light on the structural design of HEA electrocatalysts and present a promising route to achieve highly efficient electrocatalysts for industrial water electrolysis and relevant energy conversion processes.