State-of-the-art review on reduced graphene oxide for supercapacitor electrode applications

• This review discusses the application of rGO in supercapacitor electrode material. • Various methods to synthesize rGO were investigated. • The review discusses how rGO improves capacitance, power density, and its use in hybrid composites for better performance. Reduced graphene oxide (rGO) has been considered as a promising electrode material for supercapacitors due to its unique properties, including high surface area, excellent electrical conductivity, and tunable surface chemistry. However, it follows an electrical double layer charge storage mechanism that limits the energy density of the supercapacitor. This review provides a comprehensive overview of the recent advancements in rGO-based materials for supercapacitor electrode applications. The synthesis methods of rGO and their impact on structural and electrochemical properties are discussed. Despite its advantages as a supercapacitor electrode material, reduced graphene oxide (rGO) has certain limitations. To address these, researchers have recently explored combining rGO with metal sulfides, metal oxides, metal selenides, layered double hydroxides (LDHs), and conductive polymers. Investigating the synergistic effects of rGO with its electric double-layer capacitors behavior and these materials has led to the development of highly efficient electrodes with exceptional cyclic stability for advanced energy storage applications. The review also explores the role of rGO in enhancing specific capacitance and power density, as well as its integration with other nanomaterials to form hybrid composites for improved performance. Furthermore, the challenges associated with rGO-based electrodes, such as scalability, stability, and cost-effectiveness, are addressed, outlining future directions for research and development. By summarizing the state-of-the-art progress in this field, this review aims to provide valuable insights into the design and optimization of rGO-based materials for next-generation energy storage systems.