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

Abstract

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 via 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.