Ligand-hydroxylated UiO-66 for Enhanced Photothermally Catalytic VOCs Oxidation

The efficient removal of low-concentration volatile organic compounds (VOCs) in indoor and industrial environments remains a significant challenge.Metal-organic frameworks (MOFs) are potential oxidation catalysts due to their superior adsorption enrichment capability for low-concentration VOCs.In this work, hydroxyl-containing ligands were introduced into UiO-66, and the as-synthesized UiO-66-OH catalyst exhibited exceptional photothermal catalytic performance on oxidation of flowing low-concentration VOCs (an initial concentration of 0.075 mg/L for toluene and 0.064 mg/L for benzene, a weight hourly space velocity (WHSV) of 30000 mL/(gh)), achieving 97% and 90% conversion of toluene and benzene, respectively, surpassing the reported photothermal catalysts such as metal oxides and noble-metal-loaded catalysts.Such impressive activity is attributed to the synergy of thermal catalysis and photocatalysis.Ligand hydroxylation optimizes the electron structure and the ligand-to-metal charge transfer (LMCT) effect, enhancing light absorption, improving electron-hole separation efficiency and photothermal properties of UiO-66.Hydroxyl introduction promotes the formation of oxygen vacancies, facilitating oxygen adsorption/activation to sustain lattice oxygen (O latt ) and generate superoxide radical (O 2 -), which are the dominant reactive species in VOCs oxidation.This work not only presents the potential of MOFs as efficient photothermal catalysts for the oxidation of low-concentration VOCs but also shows prospective on facile modulation of electron structure by ligand engineering to enhance the photothermal properties of MOFs.