Accelerated Solar-Driven Polyolefin Degradation via Self-Activated Hydroxy-Rich ZnIn₂S₄.

Abstract

Degradation of polyolefin (PE) plastic by a traditional chemical method requires a high pressure and a high temperature but generates complex products. Here, sulfur vacancy-rich ZnIn₂S₄ and hydroxy-rich ZnIn₂S₄ were rationally fabricated to realize photocatalytic degradation of PE in an aqueous solution under mild conditions. The results reveal that the optimized photocatalyst could degrade PE into CO₂ and CO, and PE had a weight loss of 84.5% after reaction for 60 h. Systematic experiments confirm that the synergetic effect of hydroxyl groups and S vacancies contributes to improve the photocatalytic degradation properties of plastic wastes. In-depth investigation illustrates that the active radicals attack (h⁺ and •OH) weak spots (C-H and C-C bonds) of the PE chain to form CO₂, which is further selectively photoreduced to CO. Multimodule synergistic tandem catalysis can further improve the utilization value of plastic wastes; for example, product CO₂/CO in the plastic degradation process can be converted in situ into HCOOH by coupling with electrocatalytic technology.