Synergistic Coupling of Co₃O₄ and Ta₂O₅ in Nanostructured Architectures for Simultaneously Enhancing Oxygen Evolution and Urea Oxidation Reaction Kinetics

The growing demand for sustainable energy and clean water solutions has necessitated the design of efficient, stable, and low-cost electrocatalysts. In this study, we present a dual-phase Co₃O₄–Ta₂O₅ nanostructure synthesized via a simple hydrothermal route, followed by thermal annealing. By combining the catalytic activity of Co₃O₄ with the chemical stability of Ta₂O₅, we synthesized a material that performs remarkably well as an electrocatalyst for both the oxygen evolution reaction (OER) and the urea oxidation reaction (UOR). This nanocomposite possesses a unique morphology, containing Co₃O₄ and forming interconnected rod-like structures, with uniformly dispersed Ta₂O₅ particles. Carefully tuning the annealing temperature (400, 600, and 800 °C) allowed us to control crystallinity, phase formation, and surface chemistry. The sample annealed at 800 °C (CoTa-800) exhibited the best performance, offering a low overpotential (400 and 180 mV for the OER and UOR, respectively), small Tafel slopes (105 and 57 mV dec−1), and excellent long-term stability for 25 h. This study highlights that major performance improvements are possible via the meticulous material design, especially via dual-phase engineering and temperature control, of bifunctional electrocatalysis, enabling green hydrogen production and efficient wastewater treatment. © 2025 Elsevier B.V.