Effective microwave-hydrothermal reduction of graphene oxide for efficient energy storage

• Published in: Journal of energy storage Vol. 48; p. 103962
• Main Authors: Thiruppathi, Antony R., van der Zalm, Joshua, Zeng, Libin, Salverda, Michael, Wood, Peter C., Chen, Aicheng
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2022
• Subjects: Energy storage; Hydrothermal; Microwave; Reduced graphene oxide; Supercapacitor; Microwave; Supercapacitor; Reduced graphene oxide; Hydrothermal; Energy storage
• ISSN: 2352-152X; 2352-1538
• DOI: 10.1016/j.est.2022.103962

•A facile microwave-hydrothermal (MH) method for the synthesis of (rGO) is demonstrated.•The MH approach can effectively tune the structure and composition of the rGO.•The formed rGO possesses three-dimensional (3D) interconnected porous structure.•The 3D rGO exhibits a high stability and capacity for energy storage. Reduced graphene oxide (rGO) is an important member of the family of graphene-based nanomaterials. Conventional strategies for preparing rGO include chemical, thermal, photo, laser, hydrothermal, and microwave reduction. Here we report on a rapid microwave-hydrothermal (MH) method for the effective production of pure rGO (denoted as M-rGO) without using any reducing agents. The MH process was optimized in terms of temperature and duration to tune the structure and composition of the formed M-rGO to attain high specific capacitance for energy storage. The M-rGO possessed a three-dimensional (3D) interconnected porous structure with the C/O ratio of 9:5. The 3D interconnected structure of M-rGO not only increased the active surface area and enhanced the electrical double layer capacitance, but also improved its stability. Retaining the appropriate proportion of active functional groups also made a notable contribution of pseudocapacitance. The synthesized M-rGO exhibited a much higher capacitance of 298 F g−1 (1 A g−1, 0.5 M H2SO4) for a three-electrode system and 263 F g−1 (0.5 A g−1, 20% H2SO4- PVA gel) for a two-electrode system, as well as much better capacitance retention and cyclability, in contrast to conventional chemically reduced graphene oxide (C-rGO) and thermally reduced graphene oxide (T-rGO). Moreover, the energy density of the M-rGO was very high (36.6 Wh kg−1) at a power density of 0.5 kW kg−1. This first-rate energy storage performance of the M-rGO can be attributed to its highly active surface area, appropriate carbon-oxygen ratio, porous structure, and interconnected 3D morphology. [Display omitted]