Interlayer hydrogen bond-assisted poly(perylene diimide) photocatalysts to improve the oxygen evolution under visible light

In recent years, polymeric photocatalysts have attracted worldwide attention due to their diverse synthetic approaches, tunable energy band and electronic structure. However, their photogenerated charge transfer is hindered by the lack of crystallinity, thus limiting their photocatalytic activity. In this work, four poly (perylene diimide) (poly(PDI)) photocatalysts (U-PDI, OA-PDI, MA-PDI and BU-PDI) with urea, oxalamide, malondiamide and biuret as the connecting groups were synthesized, respectively. Their photocatalytic oxygen production activity and charge transfer kinetics were investigated. It was found that BU-PDI exhibited the highest oxygen evolution rate (OER) of 46.80 mu mol h(-1) (2345 mu mol g(-1) h(-1)) under visible-light irradiation, which is 2.03 times higher than that of urea based U-PDI. The high OER of BU-PDI is mainly attributed to its interlayer hydrogen bond-enhanced crystallinity, which enhances the built-in electric field by avoiding dipole cancellation resulting by the disordered assembly and thus leads to an excellent charge transfer and separation capability. Moreover, to further expand its application in the utilization of solar energy, BU-PDI was used for the photodegradation of tetracycline and showed an excellent degradation rate and stability. This work may contribute to the development of photocatalysts for applications in photocatalytic water splitting and sewage treatment.