Functionalized Graphene-MoO2 frameworks: An efficient electrocatalyst for iron-based redox flow battery and supercapacitor application with enhanced electrochemical performances

Abstract

Grid level energy storage systems have gravitated towards redox flow batteries due to their great performance, economic factors and supercapacitors have gained prime importance as they bridge the void between batteries and capacitors. The electrochemical behavior of the Iron redox flow battery is directly co-related to the positive electrode. Herein the positive electrode is modified with able metal oxide and graphene-based composite to increase the electrochemical activity of the system. MoO2-GP was synthesized using one-step hydrothermal process and characterized by XRD, SEM, EDAX, TEM, XPS, and Elemental mapping. Different Electrochemical techniques are evidenced for significant anodic and cathodic peak current densities, least charge transfer resistance, least solution resistance, reversibility, and reduced polarization resistance. A 132 cm2 IRFB with composite modified positive electrode showcased improved CE, VE, and EE. Wherein the MoO2-GP composite was also incorporated as an active material for supercapacitors, focusing to increase the stability and the Cs of the system. The combined effect of electrical double layer capacitance (EDLC) and pseudocapacitive or faradaic nature of composite material, contributed to the increased electrochemical activity of supercapacitors. The results demonstrate that the MoO2-GP composite material leaps providing better active sites, improving the reactions thus acting as an excellent electrochemically active material for energy storage devices.