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

This article reports the first instance of using vanadyl ethylene glycolate as an efficient bifunctional electro-catalyst 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.