Morphology Optimization of Spinel Catalysts for High-Efficiency Photothermal Catalytic Upcycling of Polyethylene Terephthalate

Thermocatalytic recycling of plastics is typically constrained by high energy input requirements, resulting in poor economic efficiency and necessitating the utilization of light power. Indeed, photothermal catalysis offers several advantages over traditional photocatalysis and enables more efficient use of light energy. In this study, unique octahedral spinel-structured cobalt manganese oxide (CoMn2O4) catalysts are prepared. CoMn2O4 acts as both a photothermal reagent and catalyst, demonstrating low light intensity requirements, high conversion rates, enhanced reactivity, and superior stability during polyethylene terephthalate (PET) glycolysis via photothermocatalysis. Oxygen vacancies created on CoMn2O4 facilitate PET glycolysis by providing reactive sites that promote nucleophilic addition and subsequent elimination reactions. The spinel structure of CoMn2O4 ensures high thermal stability, while the octahedral configuration enhances the optical absorption coefficient and photothermal conversion efficiency. Under identical conditions, the PET conversion efficiency of CoMn2O4 in photothermal catalysis is 3.1 times higher than under purely thermal conditions, while maintaining high selectivity for high-value monomers. This study presents a new catalyst design approach for highly efficient upcycling of plastics, highlighting its substantial potential in this field.