PET Glycolysis by Modulating the Crystal Facets of PW ₁₂ @UiO‐67: Understanding the Activation of Dual Substrates

Abstract Polyethylene terephthalate (PET) glycolysis presents an effective solution to address plastic pollution while promoting the utilization of renewable resources. It is highly important to gain in‐depth insights into the identification of the well‐defined active sites and the structure‐activity relationships in PET glycolysis. Herein, PW ₁₂ @UiO‐67 with different exposed crystal facets, i.e., octahedral PW ₁₂ @UiO‐67‐[111] and cubic PW ₁₂ @UiO‐67‐[001], are successfully synthesized by using a coordination modulation strategy. In situ DRIFTS, XPS, and XAFS characterizations confirmed that, by fine‐tuning the dosages of HAc and PW ₁₂ , PW ₁₂ @UiO‐67‐[001], endowed with the abundant exposed PW ₁₂ sites and coordination‐unsaturated Zr sites, is induced by the missing‐linker defects. The PW ₁₂ @UiO‐67‐[001] exhibited excellent catalytic performance in PET glycolysis, i.e., >99.9% PET conversion and >95.0% bis(2‐hydroxyethyl) terephthalate (BHET) yield, exceeding PW ₁₂ @UiO‐67‐[111] (with buried PW ₁₂ sites, 69.4% BHET yield). The results of in situ experiments revealed that the PW ₁₂ sites can simultaneously facilitate EG adsorption and activation, whereas the Zr sites played the crucial role in PET activation during glycolysis. Characterizations and DFT calculations verified that the abundant exposed PW ₁₂ sites exhibited more electron‐rich states, thereby optimizing EG adsorption behaviors. Notably, facet engineering‐induced missing‐linker defects effectively modulated the d‐electron configuration of Zr, shifting its d‐band center closer to the Fermi level and consequently enhancing its binding affinity with PET. The synergistic effects decreased the energy barriers for the activation of PET and EG, thereby facilitating mass transport and accelerating reaction kinetics. This work provides an atomic‐level insight into facet‐sensitivity catalytic mechanisms in PET glycolysis.