Breaking Symmetry of Active Sites in Metal‐Organic Frameworks for Efficient Photocatalytic Valorization of Polyester Plastics
Jibo Qin, Jianchi Zhou, Jin Ma, Shuang Li, Awu Zhou, Linhua Xie, Yibo Dou, Yuanjian Zhang
Abstract
Abstract Chemical upcycling of waste plastics offers a promising way toward achieving a circular economy and alleviating environmental pollution but remains a huge challenge. Inspired by hydrolase enzymes and aiming to overcome their intrinsic limitations, we put forward a design principle for an innovative nanozyme featuring asymmetric metal sites. This nanozyme functions as photocatalyst, enabling sustainable valorization of polyester plastics. As a proof of concept, an asymmetric ligand substitution strategy is developed to construct metal‐organic frameworks (MOFs) that are defective MIL‐101(Fe) (D‐MIL‐101) with asymmetric Fe 3‐δ /Fe 3+ (0< δ <1) sites. The differential electronic configurations inherent to adjacent Fe 3‐δ /Fe 3+ sites endow a high photocatalytic activity for the valorization of polyester plastic. Accordingly, the ester bonds of polyesters can be preferentially cleaved, contributing to the low energy barrier of upcycling plastics. As a result, the D‐MIL‐101 achieves a high monomer yield with terephthalic acid (TPA) of ∼93.9% and ethylene glycol (EG) of ∼87.1% for photocatalytic valorization of poly (ethylene terephthalate) (PET), beyond the efficiency of natural enzymes and state‐of‐the‐art photocatalysts. In addition, such a D‐MIL‐101 is demonstrated to be feasible for the valorization of various real‐world polyester plastic wastes in a flow photocatalysis system.