Current status of PDI-based heterojunction photocatalytic system for energy production and environmental remediation applications

Photocatalysis has shown great potential in solving environmental and energy problems. Perylene diimide (PDI) has received significant attention as a semiconductor photocatalyst. However, pure PDI photocatalysts still face challenges because of their low photogenerated carrier separation efficiency, leading to suboptimal photocatalytic activity. In recent years, PDI-based heterostructures have become a hot research topic because of their greatly improved carrier separation efficiency and photocatalytic performance. According to the different transfer mechanisms of photogenerated carriers between PDI and coupling components, PDI-based heterostructured photocatalysts can be classified into conventional type-II, Z-scheme, and S-scheme heterojunctions. This paper reviews the recent research progress in the design of PDI-based heterojunction photocatalysts and their photogenerated carrier transfer mechanisms. Subsequently, the enhanced photocatalytic activity of PDI-based heterojunctions with respect to environmental remediation and energy conversion in terms of pollutant degradation, CO2 reduction, and photocatalytic H2 evolution have been thoroughly reviewed. Moreover, the typical mechanism of the photocatalytic reaction of PDI-based composites is described in detail. Lastly, the unresolved challenges and potential applications of PDI-based heterojunction photocatalysts are presented to guide the future development direction.