Synergistic Barium–Oxygen Vacancy Catalysis Engineered with MWW Zeolites for Efficient PET Glycolytic Depolymerization

The chemical recycling of poly(ethylene terephthalate) (PET) via glycolysis is a promising route to a circular plastics economy, yet its success hinges on the development of efficient and robust heterogeneous catalysts. Herein, we report the rational design of a high-performance catalyst by stabilizing barium oxide (BaO) nanoparticles on an ultrathin, open-structured Cy4-MWW zeolite. This zeolite-directed synthesis yields highly dispersed BaO nanoclusters with rich surface oxygen vacancy (Ov). Comprehensive characterization and density functional theory (DFT) calculations reveal a synergistic "Ba-Ov" bifunctional mechanism for PET glycolysis. This spatial cooperation drives efficient transesterification, enabling near-quantitative monomer yields at mild temperature within 1 h. The catalyst demonstrates remarkable versatility by effectively depolymerizing various real-world polyester wastes. This work underscores the power of zeolite-mediated nanostructuring in creating cooperative catalytic interfaces, offering a new design paradigm for advanced catalysts in plastic upcycling.