Recent advances in graphene-semiconductor-based composites for water splitting and environmental remediation

The global shift toward sustainable energy and cleaner environments has intensified the demand for advanced catalytic systems for sustainable energy conversion and environmental remediation. Integrating graphene and its derivatives with semiconductor photocatalysts has emerged as an effective strategy to enhance charge separation, improve light absorption, and increase the overall catalytic efficiency and durability. This review outlines the versatility of graphene and its derivatives, emphasizing the critical roles of surface chemistry and interface engineering, including surface functional groups and defect engineering, π-π interactions, adsorption mechanisms, charge transfer at graphene-catalyst interfaces, and surface wettability in governing their catalytic as well as environmental performance. Various synthesis strategies for graphene-based composites such as hydrothermal methods, in-situ growth, electrochemical deposition, microwave-assisted synthesis, and template-assisted approaches are summarized with key preparation parameters. Recent advances in graphene-derived composites, such as graphene-metal oxide, graphene-metal sulfide, graphene-metal-organic frameworks, and graphene two-dimensional material systems are discussed, which demonstrate significant potential for advanced electrocatalytic and photoelectrochemical water splitting applications. Their roles in environmental remediation are also examined, encompassing dye and phenolic degradation, adsorption-based heavy-metal removal, photocatalytic metal-ion reduction, and sensitive detection of heavy-metal species. Finally, key challenges, emerging opportunities, and future perspectives are outlined to guide the development of advanced graphene-based materials for water splitting and environmental remediation.