Enhanced bifunctional catalytic activity of surface-modified vanadyl ethylene glycolate for oxygen reduction and evolution reactions

Abstract

This article reports the first instance of using vanadyl ethylene glycolate as an efficient bifunctional electrocatalyst for oxygen reduction (ORR) and evolution reactions (OER). A simple solvothermal method was employed for the synthesis of VEG and the surface-modified VEG with graphene oxide (VEG-GO). The VEG-GO catalyzes the reduction of oxygen to water via a four-electron pathway with an E1/2 value of 0.62 V and it possesses a low Tafel slope value (62 mV dec−1) compared to Pt/C (85 mV dec−1), suggesting efficient oxygen kinetic activity. It also catalyzes O2 evolution with an overpotential of 300 mV at 10 mA cm−2, and the chronoamperometry measurements revealed excellent stability for this material. With a potential difference of 0.91 V between ORR and OER, the VEG-GO is better than pristine VEG and many oxygen electrocatalysts reported in the literature. This work provides an important insight into using organic-inorganic hybrid materials as bifunctional electrocatalysts for the ORR and OER.