High-Performance\nThree-Dimensional Mesoporous Graphene\nElectrode for Supercapacitors using Lyophilization and Plasma Reduction

Abstract

In this study, a three-dimensional\n(3D) mesoporous plasma-reduced\ngraphene oxide web (mPrGO web) was fabricated via lyophilization of\ngraphene oxide (GO) solution and subsequent plasma reduction. The\nlyophilized graphene oxide web (GO web) was successfully reduced by\na short plasma treatment (<2 s) using a commercially available\nplasma apparatus. The degree of reduction of the mPrGO web was determined\nby the applied plasma power (W) of the apparatus; the optimum power\nlevel for effective reduction was identified. The as-synthesized mPrGO\nweb showed a high degree of reduction and robust graphitic characteristics,\nwith a unique crack-like mesoporous structure created on corrugated\ngraphene sheets. In addition to the above characteristics, the mPrGO\nweb possessed a 3D web-like architecture that provided enhanced surface\narea along with ion-transportable channels derived from lyophilization.\nOwing to the synergistic effect of lyophilization and plasma reduction,\nthe mPrGO web exhibited high electrical conductivity (87 S cm^–1) and increased surface area (642 m² g^–1). Accordingly, the mPrGO web showed outstanding specific\ncapacitance of 253.8 F g^–1 at 0.2 A g^–1 along with the excellent rate capability (76% capacitance retention\nat 5 A g^–1). Furthermore, the assembled all-solid-state\nsymmetric supercapacitor also exhibited remarkable electrochemical\nperformances, demonstrating the potential applicability of the mPrGO\nweb as an effective supercapacitor electrode material.