Cucurbit[8]uril-Directed Facet Engineering of Zn-Based Catalysts for PET Methanolysis

The catalytic depolymerization of polyethylene terephthalate (PET) into monomeric building blocks provides a promising pathway to advancing circular plastic recycling. Herein, we report a supramolecularly directed strategy to construct facet-engineered Zn catalysts through the assembly of cucurbit[n]urils (Q[n], n = 6, 7, 8) with Zn(II). The introduction of Q[8] enables simultaneous regulation of Zn loading, dispersion, and surface crystal structures, yielding a Q[8]-Zn composite that predominantly exposes the ZnO(101) facet. As a result, Q[8]-Zn exhibits superior catalytic activity under mild methanolysis conditions, affording an over 90% yield of dimethyl terephthalate (DMT) along with excellent durability over repeated cycles and broad applicability toward different postconsumer PET substrates. Comprehensive experimental characterizations, supported by density functional theory calculations, reveal that the coexistence of (101) and (002) facets in Q[8]-Zn generates a synergistic balance between PET adsorption and electronic activation of ester bonds, thereby accelerating the transesterification. This study demonstrates the power of macrocycle-directed facet engineering in constructing efficient and reusable heterogeneous catalysts, offering a sustainable strategy for closed-loop PET recycling.