Simultaneous Dual-Functional Photocatalysis by g-C3N4-Based Nanostructures

Heterogeneous photocatalytic reactions have experienced many efforts in developing new materials to tackle environmental and energy crises through utilizing appropriate photocatalysts in wastewater treatment, H2 generation, organic transformations, CO2 reduction, N2 photofixation, and biomass conversion. While these processes are addressed in the literature separately, a recent innovative viewpoint is to employ a photocatalytic system to achieve simultaneously two or more functions. The challenging point is that the combination of two functions in one photocatalytic system requires a novel design and engineering of an appropriate semiconductor photocatalyst with special characteristics for each application in a particular environment. Recently, graphitic carbon nitride (g-C3N4) with its unique physicochemical properties has gained tremendous attention among researchers due to its great potential for utilization as a dual-functional photocatalyst. In this study, the role of morphological engineering and band gap manipulation in heterojunction formation of g-C3N4 will be considered. These newly applied strategies are useful to improve the photocatalytic activity of g-C3N4 in different simultaneous reactions. Furthermore, detailed information on the application of g-C3N4-based materials in dual-functional simultaneous processes will be discussed in different reactions: namely, (i) photocatalytic H2 generation combined with oxidation of organic pollutants, (ii) photocatalytic mineralization of organic pollutants and reduction of the obtained CO2, (iii) photocatalytic removal of a mixture of organic pollutants and heavy metals, (iv) H+ and CO2 reduction, (v) photocatalytic H2 generation in conjunction with oxidation of organic substrates/biomass to value-added products, and (vi) simultaneous H2 and H2O2 production. These combined approaches could provide efficient and sustainable strategies for simultaneous reactions involved in both energy and environmental issues.