Electronic-Reconstructed Fe2O3/NiWO4 heterojunction nanosheets for large-current-density oxygen evolution

Abstract

Nickel tungstate-based materials emerge as effective catalysts to accelerate the kinetics of oxygen evolution reaction (OER), whereas their limited electrochemical activity and stability at industrial-level current densities necessitate structural and electronic optimization. In this paper, we explore the preparation of the self-supporting Fe₂O₃/NiWO₄ heterojunction nanosheets by a synergistic hydrothermal and vapor-phase cation exchange strategy. The optimized catalyst exhibits exceptional OER performance, requiring ultralow overpotentials of 251 and 310 mV to deliver 100 and 1000 mA cm⁻² in 1 M KOH, respectively, along with remarkable durability exceeding 120 h of continuous operation. Density functional theory demonstrates that heterointerface drives directional electron transfer from Ni to Fe sites, redistributing interfacial charge density and elevating the Ni 3d orbital energy level closer to the Fermi level. This tailored electronic configuration hastens OER reaction rate by lowering activation barriers, and shifts the rate-determining step. Furthermore, the anion exchange membrane water electrolyzer employing Fe₂O₃/NiWO₄ anode demonstrates exceptional operational efficiency, requiring only 1.67 V to deliver industrial-scale current density (1000 mA cm⁻²) and maintaining stable operation for 60 h. This work serves critical insights for development of high-performance catalysts under practical operating conditions.