Interfacial engineering of FeWO₄/Fe₂O₃ homometallic heterojunctions for synergistic electrocatalytic water splitting

Heterojunction construction is a crucial strategy in developing efficient electrocatalysts. However, their structures are not well-suited for achieving high-performance dual functions due to the surface reorganization resulting from the separation and redeposition of heterometallic centers. A novel FeWO4/Fe2O3 catalyst was synthesized via pyrolysis to form a homometallic heterojunction, which exhibits remarkable electrocatalytic activity towards oxygen/hydrogen evolution reactions and overall water splitting. DFT calculations indicate that the FeWO4/Fe2O3 heterojunctions regulate the electronic states, accelerate charge transfer, and enhance electrocatalytic activity. As anticipated, the FeWO4/Fe2O3 heterostructure produced in 1 M KOH solution exhibits a low overpotential of 315 mV at 10 mA cm(-2) for the OER and 38 mV for the HER. Furthermore, the FeWO4/Fe2O3 electrode can efficiently operate at a voltage of only 1.62 V in an electrolyzer to produce a current density of 10 mA cm(-2) and maintain exceptional stability during prolonged operation at a constant voltage.