Heteroatom bay-annulated perylene imides/g-C3N4 heterojunctions for efficient photocatalytic H2O2 evolution

Developing environmental-friendly photocatalysts with efficient photocatalytic activity is a promising way to tackle energy and environment issues. In this paper, perylene diimide (PDI) and its four derivatives (SF-HPDI, N-HPDI, S-HPDI, and Se-HPDI) with variable substituents at the bay position were synthesized and further used to construct the heterojunctions with g-C3N4 for photocatalytic H2O2 evolution. Among them, Se-HPDI/g-C3N4 heterojunction achieves the highest H2O2 production rate of 224.27 μM h–1 under visible light, which is 10.1 times higher than that of bare g-C3N4. The enhancement is because introducing substituents at the bay position increases the disparity of electron distribution between different constituent layers in heterojunctions, which is conducive to improving the interfacial electric field. Also, the load of PDIs broadens the optical absorption range of g-C3N4 and suppresses H2O2 decomposition. This work may inspire the further design of PDI-based photocatalysts.