Photothermal-assisted PMS activation over CuWO4-x/CoPc S-scheme heterojunction for efficient degradation of PET plastic

Polyethylene terephthalate is a major source of plastic pollution, posing significant environmental risks and requiring effective degradation methods. In the present work, the CuWO 4-x /Cobalt Phthalocyanine (CoPc) step-scheme (S-scheme) heterojunction was used as a photothermal-assisted photocatalyst to facilitate the degradation of polyethylene terephthalate via peroxymonosulfate activation in a cooperative photocatalytic system. The CuWO 4-x /CoPc sample exhibited optimal polyethylene terephthalate removal efficiency under the illumination conditions, reaching 83 % after the addition of 3 mM peroxymonosulfate. The influence of peroxymonosulfate dosage, aquatic environment, pH, and coexisting anions on polyethylene terephthalate degradation was thoroughly investigated. The X-ray photoelectron spectroscopy (XPS) and radical quenching experiment findings implied that the CuWO 4-x /CoPc composite followed the S-scheme heterojunction charge transfer process. Owing to the formation of the S-scheme heterojunction, the electron and hole transport and separation efficiency in the CuWO 4-x /CoPc photocatalyst was significantly enhanced. Infrared thermography images further revealed that the temperature rise of the solution during the catalytic process resulted from the photothermal property of CoPc, thus enhancing the degradation efficiency of polyethylene terephthalate plastics. Additionally, CuWO 4-x /CoPc demonstrated remarkable reusability and consistency in cycling experiments. This research presents an effective strategy by developing a photothermal-assisted S-scheme heterojunction system for the degradation of waste microplastics in aqueous environments.