Vanadium-Incorporated CoFeSe4 Heterostructures: A Bifunctional Electrocatalyst for Energy-Efficient Seawater Splitting and Sustainable Hydrogen Production

Abstract

The rational synthesis of noble-metal-free heterostructured electrocatalysts with optimized electronic and interfacial properties is crucial for efficient water splitting. Herein, CoFeSe4-based heterostructures are engineered as a bifunctional electrocatalyst for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Although CoFeSe4 shows promising activity, its performance is limited by insufficient accessible active sites, suboptimal electronic configuration, and sluggish charge-transfer kinetics. To address these limitations, to the best of our knowledge, this is the first report in which a vanadium-incorporated CoFeSe4 heterostructure (V@CoFeSe4) was synthesized through a facile one-step hydrothermal procedure. Vanadium incorporation modulates the electronic structure and band alignment, promotes charge redistribution, increases the electrochemically active surface area, and accelerates interfacial electron transport, thereby lowering the kinetic barriers associated with water-splitting reactions. Comprehensive structural, compositional, and spectroscopic analyses confirm the successful formation, compositional integrity, and stability of the heterostructured catalyst. Electrochemical impedance spectroscopy, optical band gap measurements, and Mott–Schottky analysis further demonstrate improved charge-transport characteristics and favorable semiconducting behavior. Benefiting from these synergistic effects, V@CoFeSe4 achieves a low overpotential of 300 ± 7 mV for OER and 173 ± 5 mV for HER at 10 mAcm−2, along with excellent durability and a Faradaic efficiency of 93.7%. Notably, the catalyst also exhibits efficient OER performance in seawater, underscoring its promise for practical and sustainable water-splitting applications.