Heterostructure CuO/Co₃O₄ Nanocomposite: An Efficient Electrode for Supercapacitor and Electrocatalyst for Oxygen Evolution Reaction Applications

Earth-abundant transition metal oxides (TMOs) are promising electroactive materials for electrochemical energy conversion and storage applications due to their high theoretical specific capacity, enhanced electrocatalytic activity, and mechanical durability. However, the limited cycle stability and low conductivity of TMOs remain challenging for practical application. Herein, we developed a TMO-based nanocomposite of CuO/Co3O4 via precipitation followed by the microwave hydrothermal method and used as a bifunctional electroactive material for supercapacitor and oxygen evolution reaction (OER) applications. The CuO/Co3O4 nanocomposite electrode exhibits a high specific capacity of 586 C g–1 and an excellent cyclic reversibility of 113.6% under a high current density of 20 A g–1 after 5000 cycles. Apart from the high redox properties, the strong synergistic interaction between CuO and Co3O4 significantly enhances the electrocatalytic property of the material. On continuous electrolysis in 1 M KOH solution, the OER electrode fabricated with CuO/Co3O4 nanocomposite demonstrated a moderate overpotential (ηO2) of 270 mV at j = 10 mA cm–2, a slight Tafel slope of 54 mV dec–1, and significant OER stability. These results highlight the fabrication of high-performance TMOs-based CuO/Co3O4 nanocomposite and their utilization in electrochemical energy storage and conversion devices for attaining maximum efficiency