Carbon nitride for photocatalytic water splitting to produce hydrogen and hydrogen peroxide

Semiconductor photocatalysis provides a sustainable way to solve the problems of energy crisis and environmental pollution. As a typical visible-light-response organic semiconductor photocatalyst, however, bulk carbon nitride suffers from poor photoreactivity due to the quick recombination of electron–hole pairs, low specific surface area, and weak light absorption property, which severely hampers its practical applications. This review summarizes the recent progresses of carbon nitride based photocatalysis for water splitting to produce hydrogen gas (H2) and hydrogen peroxide (H2O2). The strategies to improve the photoreactivity of carbon nitride from the aspects of the charge separation and light absorption are highlighted, which include cocatalysts modification, morphological control, crystallinity enhancement, element doping, semiconductor coupling, and surface functionalization. At last, the remaining challenges are analyzed, and the future developments of carbon nitride for photocatalytic water splitting were prospected.