Noncovalent Functionalization�of Quinone Derivatives on 2D Graphene for High Performance Pseudocapacitive Electrodes

Abstract

Redox-active organic materials have recently gained significant attention from small to large scale energy storage systems due to their natural abundance and sustainability.1,2 However, they degrade upon moderate cycling mainly due to their poor conductivity, which limits their usage. One option to tackle this issue is to deposit organic materials on conductive carbons. Herein, we report 3D interconnected xerogel composed of 2,5-dimethoxy-1,4-benzoquinone (DMQ) decorated on reduced graphene oxide sheets (DMQ@rGO), via one-step hydrothermal method. The DMQ performed dual role in the composite: 1) it provided high redox capacitance and 2) served as a spacer to mitigate rGO sheet aggregation. When binder-free optimized composition of DMQ@rGO was tested as a pseudocapacitive electrode, it showed high capacitance (650 F/g, 780 F/cm3 at 5 mV/s) and excellent capacitance retention of 99% after 25000 cycles at 50 mV/s in 1 M H2SO4. Furthermore, we used density functional theory calculations to explore the charge storage mechanism, binding energies, adsorption orientation of the molecules, charge redistribution and density of the states.