ADVANCES IN GRAPHENE OXIDE CHEMISTRY: SYNTHESIS, FUNCTIONALIZATION, AND INDUSTRIAL APPLICATIONS

Graphene oxide (GO) has emerged as one of the most versatile two-dimensional carbon nanomaterials due to its unique structural architecture, abundant oxygen-containing functional groups, tunable surface chemistry, and outstanding physicochemical properties. These features have enabled its application in a wide range of fields, including advanced nanocomposites, energy storage, catalysis, environmental remediation, biomedical engineering, and sensor technologies. This review provides a comprehensive overview of recent advances in graphene oxide chemistry, with particular emphasis on its structural characteristics, oxidation mechanisms, synthesis strategies, physicochemical properties, characterization techniques, functionalization approaches, reduction processes, and GO-based nanocomposites. Classical oxidation methods, including the Brodie, Staudenmaier, Hummers, and modified Hummers approaches, are critically evaluated in terms of oxidation efficiency, safety, scalability, and environmental impact. Recent progress in large-scale production and emerging applications of GO in lithium-ion batteries, supercapacitors, fuel cells, water purification membranes, heterogeneous catalysis, biosensors, flexible electronics, and biomedical systems is systematically discussed. The interrelationship between GO structure, surface chemistry, and functional performance is analyzed to provide a comprehensive understanding of its multifunctional behavior. Furthermore, current challenges related to scalable production, structural reproducibility, long-term stability, environmental sustainability, and biosafety are examined, along with potential strategies for future technological development. By integrating fundamental principles with recent scientific advances, this review offers a comprehensive reference for researchers and engineers in nanomaterials, materials science, chemical engineering, environmental engineering, and advanced functional materials. Finally, future research directions toward the sustainable development and commercialization of graphene oxide-based technologies are highlighted.