Recent Progress and Challenges in Perylene Small Molecules, Assemblies and Composites for Photocatalytic Hydrogen Evolution

Abstract Perylene diimide (PDI) derivatives are among the best‐known n‐type organic semiconductors because of their unique photophysical and chemical characteristics. In recent years, significant progress has been made in the development of various PDI/composites and their self‐assembled structures for photocatalytic hydrogen (H 2 ) evolution. However, the slow transport of photogenerated charge carriers, rapid charge recombination, limited catalytic activity, and instability of these materials still pose difficulties for their practical use. In order to address these problems, extensive studies have been conducted on structural modifications, molecular design, and synthesis techniques to control the morphology of self‐assembled PDI structures and create new and effective photocatalysts. In this context, perylene based small molecules, their composites with TiO 2 and g ‐C 3 N 4 , self‐assembled perylene derivatives have been designed and their roles as heterogenous photocatalysts for H 2 evolution have been investigated thoroughly in literature. In this review, the developments of PDI‐based photocatalysts for H 2 evolution are outlined under four different categories. Self‐assembled PDI nanostructures have made the most advancements among all the categories, with highest hydrogen evolution rate (HER) of 61.49 mmol g −1 h −1 while composites composed of perylene derivatives and g ‐C 3 N 4 exhibited the second highest rate of hydrogen evolution (17.7 mmol g −1 h −1 ). This review is intended to give researchers a better understanding and guidelines for designing PDI‐based and other chromophore‐based materials for efficient H 2 evolution and their further exploration for future improvement in H 2 evolution efficiencies.