Correlation between the Molecular Structure of Reducing Agent and pH of Graphene Oxide Dispersion on the Formation of 3D-Graphene Networks

Abstract

Interactions between the reducing agent and graphene oxide (GO) has crucial importance since it affects the performance of the final three-dimensional graphene networks (3D-GNs) as a supercapacitor electrode. In this study, morphological and electrochemical properties of 3D-GNs fabricated through reducing of GO by ethylenediamine (EDA), L-ascorbic acid (AA), glucose (Glu), and citric acid (CA) reducing agents have been determined. It is observed that the pH of GO dispersion, and molecular structure and pKa of reducing agents mainly determine the porosity and electrochemical behavior of 3D-GNs. All the 3D-GNs exhibit better electrochemical performance than those of GO both in acidic and alkaline electrolytes while the EDA-(3D-GN) has the highest specific capacitance values and excellent coulombic efficiency (99) thanks to its mesoporous structures consisting of restored and enlarged the graphene sheets as well as nitrogen functionalities. The maximum energy density has been calculated as high as 41.95 Wh kg−1 in 3.0 M H2SO4 for EDA-(3D-GN) based supercapacitor device which is almost 2.3 times of GO and comparable with the Lead-acid batteries. The results put forth the great potential of the 3D-GNs as efficient electrode materials for high-performance energy storage devices.