CoV₂O₆–V₂O₅ Coupled with Porous N-Doped Reduced Graphene Oxide Composite as a Highly Efficient Electrocatalyst for Oxygen Evolution

Abstract

Electrocatalysts with high intrinsic activity for the oxygen evolution reaction (OER) are greatly desired for sustainable oxygen-based electrochemical energy conversion. In this work, the bimetallic oxide composite consisting of CoV2O6 and V2O5 anchoring on nitrogen-doped reduced graphene oxide (CoV2O6–V2O5/NRGO-1) was synthesized directly by carbonization of the polyoxometalates, ethylenediamine, and graphene oxide precursors. CoV2O6–V2O5/NRGO-1 used as an electrocatalyst exhibits an ultralow overpotential of 239 mV vs RHE at the current density of 10 mA cm–2 and excellent stability in 1 M KOH. Surprisingly, it has high intrinsic activity with the turnover frequency of 1.80 s–1 at the overpotential of 300 mV, which is the highest among the electrocatalysts reported to date. Theoretical calculation proves that the outstanding electrocatalytic performance is attributed to synergistic effects, in which CoV2O6 acts as active sites while the hydrogen bond between V2O5 and intermediate HOO* of the OER greatly decreases the composite adsorption energy, thus reducing the overpotential. Most importantly, the results demonstrate for the first time that intermolecular hydrogen bonding plays a key role in improving electrocatalytic properties for the OER, which reveals a new method of designing novel OER electrocatalysts.