Regulating the photoelectric effect and built-in electric field based on the electronic and spatial effects of substituents on PDIs amide sites to enhance the photocatalytic performance of PDIs

How to design and optimize the single-molecule structure of perylene diimide derivatives (PDIs) to obtain high-performance photocatalysts is one of the challenges facing the current research field of PDIs photocatalysis. In this article, we regulate the π-π self-assembly stacking and optoelectronic properties of PDIs by changing the type and position of substituents on the amide site. The PDI-PBA photocatalyst with excellent performance was obtained from seven types of PDIs supramolecular materials. Theoretical calculations and optoelectronic performance tests have shown that PDI-PBA has good crystallinity and maximum dipole moment, resulting in its maximum built-in electric field, effectively promoting the separation and transport of photo-generated carriers. The transient absorption spectra further indicate that photogenerated electrons and holes of PDI-PBA have outstanding separation efficiency and ultra-long lifetime. In the batch reactor, PDI-PBA can degrade almost 100% acetaminophen within 60 min. In the dynamic cycling system with a surface hydraulic load of 14.56 L/(m 2 ·h), the efficiency of PDI-PBA photocatalytic degradation of acetaminophen can reach 84%. PDI-PBA can also effectively degrade phenol, levofloxacin, and ciprofloxacin. This work provides a successful example for the design of novel and efficient PDIs supramolecular materials, and lays the foundation for the application of PDIs photocatalysts in practical wastewater treatment.