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 a sustainable way to tackle the escalating plastic waste problem and create a circular plastic economy. Herein, defect-rich CeO 2 nanoparticles (NPs) with tunable sizes and shapes were conveniently synthesized by one-step precipitation with KH550 modification and first used as novel catalysts for the glycolysis of PET. Among the obtained CeO 2 catalysts, CeO 2 –2.7 nm NPs possessed the best performance for depolymerization at 196 °C, completing the reaction in 15 min with a PET conversion of 98.6% and a monomer yield of 90.3%. The glycolysis mechanism study reveals the relationship between defect engineering and catalytic activity. An ultrasmall size of 2.7 nm minimizes oxygen defect formation energy of CeO 2 NPs and increases the dispersity in ethylene glycol (EG). Rich oxygen defects on CeO 2 nanoparticles accelerate the glycolysis reaction evidently via inducing the generation of Ce 3+ and providing sites for the adsorption and activation. This work provides the application prospect of defective heterogeneous catalysts in the depolymerization reaction under low energy consumption.