Singlet Oxygen Photosensitization Using Graphene-Based Structures and Immobilized Dyes: A Review

Singlet oxygen (1O2) has been widely produced utilizing nanostructure-based photocatalysts, purposed for photodynamic therapy (PDT), wastewater treatment, and photo-oxygenation reactions. A rational design of heterogeneous photocatalysts is important for a high 1O2 quantum yield under visible-light or near-infrared irradiation. The present review provides insights for graphene-based photocatalyst design by summarizing the mechanism and fundamental aspects of 1O2 sensitization, as well as offers a summary of experimental realization. Subsequently, we go through works done on light-driven 1O2 sensitization utilizing graphitic carbon nitride, carbon dots, graphene quantum dots, and graphene oxide, as well as immobilized organic dyes on polymeric and silica supports, followed by their applications. Moreover, the effect of surface passivation, hybridization with other materials, doping with metal or nonmetal atoms, plasmonic fields, and self-assembly aggregation on the 1O2 quantum yield and 1O2 enhancement factor is discussed. We also provide perspectives for the 1O2 sensitization including applying machine learning (ML) to optimize the plasmonic field and 1O2 quantum yield.