Heteroatom engineering of polymeric carbon nitride heterojunctions for boosting photocatalytic reduction of hexavalent uranium

Herein, for the first time, the authors report metal-free heterojunction photocatalysts consisting of push-pull conjugated polymers and polymeric carbon nitride (CN) for efficient reduction of uranium. Furthermore, the authors innovatively proposed a heteroatomic engineering strategy to further improve the visible-light capture ability and separation of electron-hole pairs of heterojunction photocatalysts via replacing carbon atoms in donors by nitrogen atoms. The result revealed that in the photocatalytic reduction of uranium, the kinetic constant of PFB/CN (0.037 min(-1)) was 2.47 times higher than that of CN (0.015 min(-1)). Notably, copolymerization of a nitrogen-containing electron donor carbazole unit into the polymer backbone would further widen the light response range and promote electron-hole separation within PCB/CN as compared to PFB/CN, leading to a higher kinetic constant (0.049 min(-1)), 3.27 times higher than that of CN. The current work underlines that adapting a reasonable heteroatomic engineering strategy for polymer heterojunctions is a remarkably effective strategy to develop up-and-coming organic semiconductor photocatalysts for efficient reduction of uranium.