Vertically aligned 3D core–shell CuO/ZnCO2O4 supported on a flexible mesh for efficient and scalable electrochemical water splitting†

Non-precious electrocatalysts used in anodic electrodes encounter significant challenges such as inadequate long-term durability, structural instability, small catalytically active surface area, low conductivity, and suboptimal electron absorption and desorption capabilities. However, developing a commercially viable oxygen evolution reaction (OER) electrocatalyst for circumventing all these shortcomings remains a challenge. Driven by the need to address this critical issue, herein, we report the fabrication of a highly porous core–shell network of a three-dimensional CuO/ZnCo₂O₄@flexible stainless steel mesh (3D CuO/ZnCo₂O₄@FSSM) as an anodic electrode via a facile two-step reflux condensation and successive ionic layer adsorption and reaction (SILAR) technique. The 3D CuO/ZnCo₂O₄@FSSM electrode exhibited superior electrocatalytic activity at a lower overpotential of 220 mV at a current density of 10 mA cm⁻² and a small Tafel slope of 70 mV dec⁻¹ for the OER. Interestingly, the electrode revealed significantly reduced overpotential in 1 M KOH after a 25 h chronopotentiometry stability test, which was markedly lower than the initial pre-stability overpotential, which could be attributed to the rate-determining step (M–O). Furthermore, large-scale OER tests revealed exceptional 19.6 L oxygen evolution with 70 h long-term stability, which signifies its robustness and justifies the advancement of earth-abundant materials as highly active anodic electrodes. By exhibiting an increased electrochemically active surface area, high turnover frequency, and low intrinsic resistance, 3D CuO/ZnCo₂O₄@FSSM offered a solid foundation for developing next-generation electrochemical water splitting systems, which may be a probable alternative to precious metal-based devices.