Oxygen vacancies promoting the electrocatalytic activity of dual-shelled Co₃V₂O₈ hollow sphere catalyst for efficient oxygen evolution

Developing cost-effective and highly active electrocatalysts for the oxygen evolution reaction (OER) is critical for advancing water splitting technologies. Herein, we report a dual-shell Co₃V₂O₈ hollow sphere catalyst with abundant oxygen vacancies synthesized <i>via</i> a facile hydrothermal method followed by controlled reduction treatment. The unique dual-shell hollow architecture provides a large surface area and exposes abundant active sites, while the introduced oxygen vacancies optimize the electronic structure of Co₃V₂O₈, enhancing electrical conductivity and intrinsic catalytic activity. The optimized catalyst exhibits outstanding OER performance, requiring a low overpotential of 376 mV to achieve a current density of 10 mA cm^-2 in alkaline media, along with a small Tafel slope of 86.9 mV dec^-1. Experimental analyses reveal that oxygen vacancies facilitate charge transfer during OER. Moreover, the catalyst demonstrates excellent durability with negligible activity decay after 12 h of continuous operation. This work highlights the synergistic effect of structural engineering and defect modulation in designing high-performance OER electrocatalysts, offering a promising strategy for energy conversion applications.