Gold-graphene quantum dot hybrid nanostructures for solar-to-chemical energy conversion: interfacial charge dynamics,...

Gold-graphene quantum dot (Au-GQD) hybrid nanostructures provide a versatile platform for coupling plasmonic light harvesting, quantum-confined carbon states, and interfacial redox activity in solar-to-chemical energy conversion. However, the field remains mechanistically fragmented, and the roles of Au, GQDs, and their evolving interface are often insufficiently distinguished. This review establishes a unified framework linking electronic structure, surface chemistry, interfacial coupling, photon utilization, excited-state partitioning, carrier transport, and surface redox turnover. It critically analyzes how Au size, GQD surface states, heteroatom functionality, contact geometry, and energetic alignment govern structure-property-performance relationships. Available evidence for hydrogen evolution and water splitting is examined alongside supporting studies on plasmonic absorption, hot-electron transfer, and type-II charge separation, while distinguishing direct solar-fuel conversion from indirect optical or photoelectronic responses. The synthesis reveals that productive performance depends not on simple component coexistence, but on function-specific interfacial organization and preservation of redox-competent carriers. Major limitations include inconsistent material identity, structural reconstruction, nonstandardized performance metrics, limited operando validation, and uncertain scalability. The review concludes with design priorities for stable, low-Au, spatially organized architectures and standardized evaluation pathways toward reproducible solar-fuel systems. This is the first dedicated review focusing specifically on Au-GQD hybrid nanostructures for solar-to-chemical energy conversion, providing an integrated analysis of their interfacial physicochemical properties and functional roles.