Ultrasmall CeO2 Nanoparticles with Rich Oxygen Defects as Novel Catalysts for Efficient Glycolysis of Polyethylene Terephthalate

Chemical recycling of polyethylene terephthalate(PET) attracts increasing attention worldwide since it is asustainable way to tackle the escalating plastic waste problemand create a circular plastic economy. Herein, defect-rich CeO2nanoparticles (NPs) with tunable sizes and shapes wereconveniently synthesized by one-step precipitation with KH550modification andfirst used as novel catalysts for the glycolysis ofPET. Among the obtained CeO2catalysts, CeO2-2.7 nm NPspossessed the best performance for depolymerization at 196 degrees C,completing the reaction in 15 min with a PET conversion of 98.6%and a monomer yield of 90.3%. The glycolysis mechanism studyreveals the relationship between defect engineering and catalyticactivity. An ultrasmall size of 2.7 nm minimizes oxygen defectformation energy of CeO2NPs and increases the dispersity in ethylene glycol (EG). Rich oxygen defects on CeO2nanoparticlesaccelerate the glycolysis reaction evidently via inducing the generation of Ce3+and providing sites for the adsorption and activation.This work provides the application prospect of defective heterogeneous catalysts in the depolymerization reaction under low energyconsumption