Structural control of crumpled sulfur-assisted reduced graphene oxide with elemental sulfur for supercapacitor

Abstract

Crumpled graphene oxide (C-GO), a three-dimensional (3D) structured material, has many advantages that can be of value in high-performance supercapacitor electrodes. However, graphene oxide loses its morphology and advantages during the solution reduction process with polar solvents, which leads to restacking of individual sheets. In this work, we introduce an eco-friendly and simple C-GO reduction method using elemental sulfur. Since sulfur is a nonpolar and antisolvent for the hydrophilic C-GO, sulfur avoid interacting with the various groups of C-GO that contains oxygen. Therefore, sulfur can be used as a reducing agent for C-GO without destroying its crumpled structure. Moreover, when C-GO is reduced by sulfur (crumpled sulfur-assisted reduced graphene oxide [C-SrGO]), it is assisted with sulfur molecules, which provide active sites for electrochemical reactions. Even better, sulfur can be used in place of hydrazine, which is a very toxic and unstable material. The structural and chemical advantages of C-SrGO resulted in better electrochemical performance than C-GO reduced by hydrazine (crumpled hydrazine-reduced graphene oxide [C-HrGO]). The C-SrGO exhibited 260 F g(-1) and the symmetric full cell remained above 88% of full capacity after 15 000 cycles. The results of our research demonstrate its potential as an electrode material for many various energy storage systems which are supercapacitors, catalysts, and lithium batteries.