Donor Bandgap Engineering without Sacrificing the Reduction Ability of Photogenerated Electrons in Crystalline Carbon Nitride

Graphical Mind the gap : A series of heptazine-based K + -implanted crystalline carbon nitride (CCN) materials with narrow bandgap (2.87–1.86 eV) are constructed by copolymerization of pyrimidine donor, which exhibits a superior photoactive wavelength to CCN-based photocatalysts. This work offers a universal donor bandgap strategy without sacrificing the reduction ability of photogenerated electrons towards photocatalytic reduction reactions. Crystalline carbon nitride (CCN) with a light response up to 700 nm has been seldom reported but is significant for the artificial photocatalysis. In this study, it is proposed that, unlike acceptors, introducing donors can effectively narrow the bandgap without sacrificing the reduction ability of photogenerated electrons, which is more advantageous to photocatalytic reduction reactions. Hence, a series of heptazine-based K + -implanted CCN (KCN) with a narrow bandgap (2.87–1.86 eV) are constructed by copolymerization of pyrimidine donors. The optimized photocatalysts can extend the light response to 700 nm and account for approximately 122- and 33-fold enhancements in H 2 production ( λ >500 nm) in comparison to CN and KCN, respectively. The apparent quantum efficiency (AQE) can reach 8.2 % at 500 nm and is comparable to the top-level CN- and CCN- based materials. Its photoactive wavelength has significant advantages over previously reported CCN-based photocatalysts. This method offers a universal donor bandgap engineering strategy towards photocatalytic reduction reactions.