Recent Developments in Graphitic Carbon Nitride Based Hydrogels as Photocatalysts

Solar-driven photocatalysis with graphitic carbon nitride (g-C3N4) is considered to be the most promising approach for the generation of H-2 from water, the degradation of organic pollutants, and the reduction of CO2. However, bulk g-C3N4 exhibits several drawbacks, such as a low specific surface area, high defect density, and fast charge recombination, which result in low photocatalytic performance. The construction of 3D porous hydrogels for g-C3N4 through nanostructural engineering is a rapid, feasible, and cost-effective technique to improve the adsorption capability, stability, and separability of the hydrogel composite; to increase the number of active sites; and to create an internal conductive path for facile charge transfer and high photocatalytic activity. This minireview summarizes recent progress in photocatalytic water splitting and dye degradation by using g-C3N4-based hydrogels, with respect to state-of-the-art methods for synthesis, preparation, modification, and multicomponent coupling. Furthermore, comprehensive outlooks, future challenges, and concluding remarks regarding the use of g-C3N4-based hydrogels as highly efficient photocatalysts are presented.