Role of Graphene Oxide and Reduced Graphene Oxide in Electric Double-Layer Capacitors: A Systematic Review

The evolution of electric double-layer capacitors (EDLCs) has significantly benefited from advancements in graphene-based materials, particularly graphene oxide (GO) and reduced graphene oxide (rGO). This systematic review consolidates and analyzes existing research on the roles of GO and rGO in enhancing the performance of EDLCs, focusing on synthesis methods, electrode fabrication, electrolytes, and performance metrics such as capacitance, energy density, and cycling stability. Following the PICOS and PRISMA frameworks, a comprehensive literature search was conducted across Scopus, Web of Science, PubMed, and IEEE Xplore, covering the period from 2010 to 2023. A total of 128 articles were initially identified, with 27 studies meeting the inclusion criteria after rigorous screening and full-text analysis. Key findings reveal that the incorporation of GO and rGO in EDLCs leads to significant improvements in specific capacitance, energy density, and cycling stability. Notable advancements include novel synthesis techniques and composite materials such as nitrogen-doped graphene, graphene/polyaniline hybrids, and various metal oxide–graphene composites, which exhibit superior electrochemical performance. However, challenges such as material scalability, environmental sustainability, and consistency in synthesis methods remain. This review stresses the great potential of GO and rGO in the development of high-performance EDLCs and highlights the need for continued research to address existing challenges and further optimize material properties and fabrication techniques.