Ultrafast Graphitization and Reduction of Spongy Graphene Oxide by Low-Energy Electromagnetic Radiation to Boost the Performance and Stability of Carbon-Based Supercapacitors

Abstract

Interest in carbon nanomaterials for energy storage systems such as supercapacitors has enormously risen due to their attractive electrical conductivity, chemical inertness, and charge storage capacity. The reduction of graphitic oxide is a versatile procedure to prepare 3D graphene. Despite many green methods, the dynamics behind ultrafast thermal graphitization have remained elusive. Here, we demonstrate an effort to understand the graphitization mechanism of graphitic oxide under ultrafast thermal reduction induced by electromagnetic radiation and probably via Ar+ cation collisions. The low photon energy (10.5 mu eV) locally removes oxygen functionalities and restores the pi-conjugated structures. A graphitic structure with low-defect, long-range order, and relatively high electrical conductivity (8.7 S cm(-1)) is attained at a short photoinduced time (15 s) and relatively low power (1000 W) after a hydrothermal reduction at 160 degrees C for 2 h. We demonstrate that the prepared spongy graphene structure microwaved for 13 s is an active charge storage material with a specific capacitance of 226.4 F at 1 A an ultrahigh rate capability of 85.1% in the range of 0.2-50 A g(-1) and a capacitance stability of 120% after 10,000 cycles at 1 A g(-1). The ultrafast photoreduction of graphitic oxide for the mass production of graphene sponges paves the way for fabricating functional materials by tailoring oxygenated functional groups for multiple applications.