Synthesis and Characterization of Reduced Graphene Oxide for Supercapacitors

• Reduced graphene oxide (rGO) was synthesized using a green hydrothermal method with L-ascorbic acid as an eco-friendly reducing agent. • Variation in GO-to-ascorbic acid ratios significantly influenced crystallinity, defect density, and sheet morphology. • XRD and Raman analyses confirmed progressive restoration of graphitic domains with increased reductant concentration. • SEM and EDS results revealed improved layered structure and reduced oxygen content in samples rGO-3 and rGO-4. • Samples rGO-3 and rGO-4 exhibited superior structural and electrochemical characteristics, making them strong candidates for high-performance supercapacitor electrodes. • The study demonstrates a sustainable and tunable synthesis approach for developing advanced carbon-based materials for energy storage applications. Abstract In this study, a hydrothermal method was employed for synthesizing rGO, utilizing L-ascorbic acid as a reducing agent, and varying the Graphene Oxide (GO) -to-ascorbic acid molar concentrations of 1:0.5, 1:1, 1:1.5 and 1:2 to ascertain its impact on its properties. The X-ray diffraction (XRD) patterns indicated that increasing concentrations of ascorbic acid resulted in increased crystallite size and restoration of the graphitic domains of rGO. Raman spectroscopy was also performed, showing that increasing concentrations of ascorbic acid resulted in varying defect densities, indicated by ID/IG values of 0.88-1.00, indicating that increasing concentrations of ascorbic acid resulted in increased restoration of the sp² carbon domains of rGO. The SEM analysis indicated that increasing concentrations of ascorbic acid resulted in crumpled sheet structures of rGO, which was also confirmed by EDS analysis showing that increasing concentrations of ascorbic acid resulted in oxygen content in rGO. The test results showed that rGO-3 and rGO-4 have better properties, indicating that these two have the ability to be used as electrode materials in super capacitor applications. The experiment was able to confirm that L-ascorbic acid is a viable reducing agent for the synthesis of rGO through a green process that is controllable, allowing for changes in its properties. The data obtained from the characterization of the samples has shown that rGO-3 and rGO-4 have higher crystallinity and purity, which makes them more suitable for applications requiring high conductivity, such as supercapacitor electrodes. Electrochemical results demonstrate that the optimized rGO-4 sample exhibits superior charge storage capacity, achieving a discharge time of 340 s and a calculated Areal Capacitance of 1020 mF/cm², confirming its suitability for high-performance super capacitor electrodes.