Electronic Structure Modulation Coupled with Vacancy Defect Engineering in FeCoNiCrV High-Entropy Alloy Electrocatalyst for Enhanced Oxygen Evolution Reaction

Strategic engineering of composition and defects in high-entropy alloy (HEA) catalysts represents a critical frontier for advancing catalytic technologies, yet this synergistic approach remains underexplored in current materials research. In this study, a FeCoNiCrV HEA electrocatalyst was directly synthesized on flexible carbon cloth via filtered cathode vacuum arc deposition, where sacrificial dopants (Cr and V) were precisely integrated into a FeCoNi-based HEA matrix. The deliberate integration of Cr and V modulated the electronic structure of the catalyst. The optimized FeCoNiCrV catalyst demonstrates exceptional oxygen evolution reaction (OER) performance in alkaline media, achieving an ultralow overpotential of 254 mV at 10 mA cm–2 and exceptionally operational stability, sustaining 710 h at 20 mA cm–2. In situ/ex situ characterization reveals that the FeCoNiCrV HEA undergoes dynamic self-reconstruction during OER, where selective leaching of Cr/V species generates abundant oxygen vacancies while preserving structural robustness. These vacancy sites enhance charge transfer kinetics and modulate the adsorption energetics of oxygen-intermediate species through electron redistribution. The synergy between multimetallic coordination and defect-rich architecture enables simultaneous optimization of catalytic activity and long-term stability. This work elucidates a universal design principle for defect engineering via electrochemical self-reconfiguration for HEA electrocatalysts, offering atomic-level insights into the structure–activity interplay of complex multicomponent systems.