Electrochemical tuning of capacitive response of graphene oxide

TL;DR

This study demonstrates that the capacitance of graphene oxide can be precisely tuned through electrochemical reduction, balancing oxygen functional groups and conductivity to optimize energy storage performance.

Contribution

It introduces a simple electrochemical reduction method to control and optimize the capacitive response of graphene oxide.

Findings

Capacitance peaks at an optimal oxygen functional group concentration.

Further reduction causes a decline in capacitance.

The trend is consistent across different GO preparation methods.

Abstract

Increasing energy demands of modern society requires deep understanding of the properties of energy storage materials as well as their performance tuning. We show that the capacitance of graphene oxide (GO) can be precisely tuned using a simple electrochemical reduction route. In situ resistance measurements, combined with cyclic voltammetry measurement and Raman spectroscopy, have shown that upon the reduction GO is irreversibly deoxygenated which is further accompanied with structural ordering and increasing of electrical conductivity. The capacitance is maximized when the concentration of oxygen functional groups is properly balanced with the conductivity. Any further reduction and de-oxygenation leads to the gradual loss of the capacitance. The observed trend is independent on the preparation route and on the exact chemical and structural properties of GO. It is proposed that an improvement of capacitive properties of any GO can be achieved by optimization of its reduction conditions.