Ligand Engineering of UiO-66 for CO₂-to-DMC Reaction: Unraveling the Role of Acidity, Defects, and Electronic Effects in Catalytic Performance

This study systematically investigates how organic ligand modifications—chain length adjusting and functional group incorporation—regulate the catalytic performance of UiO-66 derivatives for CO₂-to-dimethyl carbonate (DMC) conversion. Through multi-technique characterization (Py-IR, TGA, FT-IR, XPS, etc.) and catalytic tests, Lewis acid/basic sites (LAS/LBS), bulk defects and electron density effects were identified as the three key factors to govern the catalytic activity. The bulk defects were believed to enhance mass transfer. Notably, MOF-801 (shortest ligand) and UiO-66-Br (electron-withdrawing-Br) achieved the highest TOFs of 0.86 h⁻¹ and 1.10 h⁻¹, respectively. While LAS/LBS and electron-rich Zr clusters promote methanol activation, defect-enhanced mass transfer dominated over electronic effects in boosting DMC yield. These insights highlight the tunability of MOFs for CO₂ utilization via rational ligand design.