Internal electric field in carbon nitride-based heterojunctions for photocatalysis

Carbon nitride is one of the most promising metal-free photocatalysts to harvest solar light for energy conversion and pollutant treatment. Unfortunately, its photocatalytic performance is impeded by the sluggish charge car-riers due to the high symmetry of unit cells of chemical structure. Fabrication of an internal electric field (IEF) in carbon nitride-based photocatalysts is evidenced to be a productive strategy to actuate the fast separation of photo-excited charge carriers and navigate their migrations to active sites for high apparent quantum efficiency (AQE) and throughputs. In the current work, a comprehensive review of IEF in different types of carbon nitride -based heterojunctions will be well presented. Emphasis will be put on the latest progress of IEF generation by hosting 2-dimensional (2D) carbon nitride nanosheets with different dimensional materials, IEF modulation by interfacial engineering as well as IEF identification and monitoring. Relationships between IEF and photo -catalytic performances in various processes will also be enlightened. Finally, this review will suggest the chal-lenges and future perspectives of IEF-driven photocatalysis. This review brings the intrinsic impetus of charge carriers in a photocatalyst to the forefront and is anticipated to provide guidance to configure powered IEF in 2D carbon nitride-based heterostructures toward efficient energy conversion and environmental purification.