A cost-effective Co₃O₄@WO₃ hetero-structure derived from WO₃@Co-CoPBA for oxygen evolution reaction

The oxygen evolution reaction (OER) is hindered by the sluggish kinetics, high costs, and poor stability of noble metal catalysts (e.g., RuO₂), as well as low atomic utilization and limited accessibility of active sites in transition metal oxide catalysts. To address these challenges, this study develops a core-shell structured WO₃@Co-CoPBA heterostructure as an efficient OER electrocatalyst. Co-CoPBA nanocubes are hydrothermally synthesized and then loaded with WO₃ nanorods, followed by gradient annealing under N₂ atmosphere (optimized at 500 °C) to form a Co₃O₄@WO₃ heterojunction. Characterization and electrochemical evaluations reveal that annealing at 500 °C induces topological reconstruction of Co-CoPBA into porous Co₃O₄ and graphene cores, Co sites in Co₃O₄ serve as the catalytic active centers, forming a strong electronic coupling interface with the WO₃ shell. This architecture significantly enhances the density of active sites (electrochemically active surface area of 3.8 cm²) and charge transfer efficiency (Tafel slope of 55.12 mV dec^-1). The catalyst delivers an overpotential of 315 mV at 100 mA cm^-2 in 1 M KOH, outperforming commercial benchmark catalyst RuO₂ (372 mV). It exhibits exceptional stability with almost no performance decay after 100 h. Density functional theory (DFT) calculations demonstrate that interfacial electronic restructuring modulates the d-band center, optimizing the adsorption Gibbs free energy of OOH* intermediates and thereby improving intrinsic catalytic activity. This work provides an effective interface engineering strategy for designing high-performance, low-cost transition metal-based electrocatalysts.