Vanadium–cobalt oxyhydroxide shows ultralow overpotential for the oxygen evolution reaction

Abstract

Transition metal oxyhydroxides are one of the most effective electrocatalysts for the oxygen evolution reaction (OER), which is often considered as a bottleneck in the water splitting process. Herein, a cation-modulated V–Co-based oxyhydroxide one-dimensional scaffold configuration (Co_1−xV_xOOH) assembled using uniform ∼4 nm thick nanosheets is reported, which demonstrates superb OER activity and durability. Theoretically, the Co sites adjacent to V in the bimetal samples have the maximum required energy of 0.37 V (*O → *OOH) when combined with 20% V (Co_0.8V_0.2OOH), which is favorable for enhancing the OER activity with the ultralow overpotential of 190 mV vs. the current density of 10 mA cm⁻², Tafel slope of 39.6 mV dec⁻¹ and remarkable durability over 100 h. To the best of our knowledge, the overpotential of 190 mV at 10 mA cm⁻² is the best value reported to date for Co or V (oxy)hydroxide-based OER catalysts. The outstanding activity is ascribed to the hierarchically stable scaffold configuration, high electrochemically active surface area, enhanced oxygen vacancies on the surface and the synergistic effect of the active metal atoms. This study affords a strategy for the rational design of earth-abundant electrocatalysts for energy conversion applications.