Construction and performance of a novel perylene diimide/AgI S-scheme heterojunction photocatalyst for various pollutants degradation

A series of novel self-assembled perylene diimide (SAPDI) attached AgI photocatalysts (SAPDI/AgI) were successfully prepared by the chemical precipitation method. Different characterizations were used to test their chemical structures, appearance and morphology, and optical properties. The results showed that rod-shaped SAPDI tight loaded on the surface of granular AgI. The prepared SAPDI/AgI composites not only could greatly improve the light absorption capacity and broaden the light absorption range, but also could effectively reduce the recombined probability of photogenerated charge and improve the photodegradation efficiency. The mass ratio of AgI and SAPDI was 60:1, as-prepared SAPDI/AgI-60 had the largest degradation rate of Rhodamine B (RhB) under visible light. The degradation rate constant was 0.0695 min⁻¹, which was 2.59 times of that of AgI (0.02687 min⁻¹). And SAPDI/AgI-60 maintained good degradation effect after 3 cycles of degradation experiments. In addition to RhB, the SAPDI/AgI-60 also showed good photodegradation of methylene blue (MB), methyl orange (MO), and tetracycline hydrochloride (TC). Obviously, a photocatalyst with visible-light-induced various pollutants degradation ability is synthesized. Finally, based on the work functions of SAPDI and AgI, the S-scheme heterojunction photocatalytic mechanism is proposed.