Highly Efficient Photothermal‐Catalytic Depolymerization of Polyester Fiber Enabled by a Phosphotungstate‐Based Palladium Single‐Atom Catalyst

The chemical inertness and thermal stability of plastics contribute to their durability and stability across a wide range of applications. However, these same properties present significant challenges for their recycling under mild conditions. In this study, a novel photothermal catalytic system is developed featuring Pd single-atom catalysts (SACs) anchored on activated carbon for the efficient and rapid photothermal depolymerization of polyethylene terephthalate (PET) by ethylene glycol (EG). Different from top-down lighting used in other studies, side lighting is used to avoid the negative influence of EG evaporation on the photothermal conversion. By optimizing the structure of the catalyst, near complete PET decomposition within 4 h under a light intensity of 0.5 W cm^-2 is achieved. Density functional theory (DFT) calculations reveal for the first time that the unique electronic structure of palladium (Pd) facilitates the nucleophilic attack of EG on PET. The strong coordination between the carbonyl oxygen in PET and the Pd significantly lowers the reaction energy barrier from 37.44 to 26.77 kcal mol^-1. This study presents a promising strategy for designing efficient catalysts, offering a cost-effective and sustainable solution for PET recycling.