Crystallinity-Modulated Co2-xVxO4 Nanoplates for Efficient Electrochemical Water Oxidation

Cost-efficient and durable oxygen evolution catalysts are in great demand, which are dominated not only by the component of the electrocatalysts but also by their molecular structure and crystallinity. Herein, we developed an efficient cobalt-vanadium spinel-type electrocatalyst with an extremely high concentration of Co3+ ions by tuning the balanced vanadium ions' concentration in crystallinity-modulated Co2-xVxO4 nanoplates. This resulted in the lowest overpotential of 240 mV at 10 mA/cm(2), the smallest Tafel slope of 45 mV dec(-1), and a current density of 100 mA/cm(2) at an overpotential of 280 mV for water oxidation, which is remarkably 20 times better than that of the benchmark RuO2 catalyst, along with excellent stability. Such excellent performance is due to the very high Co3+/Co2+ ratio of 2.84 achieved in situ in the lowcrystallinity Co2-xVxO4 (LC-Co2-xVxO4) sample, which is 40% higher than that of the widely reported Co3O4, as evidenced by both operando X-ray absorption near-edge spectroscopy and in situ X-ray photoelectron spectroscopy. These findings stimulate the opportunities to explore Co2-xVxO4 as a class of nonprecious-metal-based efficient OER electrocatalysts.

Automated summary

Researchers have developed an efficient cobalt-vanadium spinel-type electrocatalyst with high Co3+ ion concentration by modulating the crystallinity of Co2-xVxO4 nanoplates. This catalyst shows significantly better performance than the benchmark RuO2 catalyst and offers excellent stability, opening up opportunities for exploring Co2-xVxO4 as a class of non-precious-metal-based efficient OER electrocatalysts.