Photocatalysts based on polymeric carbon nitride for solar-to-fuel conversion

During the past years, polymeric carbon nitrides (CNs) have shown excellent ability toward photocatalytic water reduction and CO2 reduction, as a promising means of efficient solar-to-fuel conversion. This chapter provides a comprehensive overview of strategies for enhancing the performance of CN-based photocatalysts in H2 production and CO2 reduction. The strategies include (1) increasing charge carrier generation by hollow structure creation, elemental doping, and molecular structure modification; (2) boosting charge separation by reducing the thickness of CNs, improving the crystallinity of CNs, and creating heterostructures of metal/CNs, graphene/CNs, type II, and direct Z-scheme heterojunctions; and (3) promoting the surface catalytic process by creation of porous structure and surface defects, construction of hybrid materials with metal–organic frameworks and layered double hydroxides, and facet tuning of metal cocatalysts. Finally, the concluding remarks and the current challenges are highlighted with some perspectives for the future development of CN-based photocatalytic materials.