Perylene diimide/iron phthalocyanine Z-scheme heterojunction with strong interfacial charge transfer through π-π interaction: Efficient photocatalytic degradation of tetracycline hydrochloride.

The development of an all-organic Z-scheme heterojunction photocatalyst with the matched band structure, efficient electron transfer and excellent photocatalytic performance is valuable for a sustainable future. A novel perylene diimide/phthalocyanine iron (PDI/FePc) heterojunctions with strong π-π interaction were synthesized by a self-assembled method, which exhibited strong visible-light-driven photocatalytic degradation activities of tetracycline hydrochloride (TC). The TC removal rate over PDI/FePc was achieved three times and 87.5 times higher than that of PDI and FePc. PDI/FePc (131.1 mv·dec-1) presented a lower Taffel slope than that of PDI (228.6 mv·dec-1) for the oxidation. This may be due to the strong π-π interactions between PDI and FePc, which can reduce the layer spacing of the supramolecular structure and facilitate the separation and transfer of photogenerated carriers in the built-in electric field. In addition, radical quenching tests revealed that superoxide radicals (•O2-) acted as a dominant role in photocatalytic oxidation. An increscent specific surface area of PDI decorated by FePc also gave the rapid pathway for charge transfer and enhanced the adsorption ability. This provides a new idea for the formation of heterojunction to improve the photocatalytic activity of organic supramolecular materials.