Graphene Quantum Dot beyond Electrocatalyst: An In Situ Electrolyte Catalyst towards Improved Reaction Kinetics of VO2+/VO2 + Redox Couples

Abstract

Graphene quantum dots (GQD) have been used in various potential applications due to their range of attractive properties such as high conductivity, good chemical resistance, very good optical properties and etc. Very first time, in this study, the GQD is used as a molecular catalyst; here the given volume of GQD around 300 μl is dispersed in as prepared vanadium based electrolyte. It is observed that the CV curve of the GQD incorporated electrolyte showed significant variation in the electrochemical activity of VO2 +/VO2+ redox reaction. The resistive behavior obtained from the EIS analysis of GQD showed highly enhanced values when compared with the bare electrolyte. The addition of GQD in the active electrolyte showed great improvement in the VO2 + to VO2+ redox reaction kinetics which is evidenced from the obtained kinetics parameters such as exchange current density, rate constant and etc. The GQD added electrolyte showed excellent improvisation in the exchange current density value of i 0 = 6.175 × 10−4 A cm−2 which is two-fold higher than the bare electrolyte (i 0 = 2.365 × 10−4 A cm−2). Thus, the idea of using GQD will play potential effect in various electrochemical applications.