Constructing a built-in electric field by grafting strong electronegative small molecules for photocatalytic H production.

Asymmetric carbon nitride (FCN) is developed by grafting strong electronegative small molecules onto CN. The introduction of these small molecules enhances the visible light absorption range and redistributes the charge density. Combining DRS, KPFM, and DFT results, it is revealed that the strong built-in electric field and the effective spatial separation of redox sites contribute to the directional charge separation and migration for superior photocatalytic H evolution. The FCN shows robust photocatalytic stability for generating H as long as 23 h. It is hoped that this catalyst, produced by one-step polymerization with a high internal driving force for charge separation, will provide a solid basis for improving H production performance in the future.