Asymmetric electron distribution of Ce (IV)/Zr (IV) cornerstones in multivariate MOF-808: unlocking improved activation and micropollutants removal

Current remediation strategies focus on either adsorption or degradation for removing pharmaceuticals; however, few studies consider the integrated approach. We report the development of a series of bimetallic Ce/Zr-MOF-808 that exhibited improved activity for micropollutant removal. Multivariate MOF-808 (Zr_3.84Ce_2.04) demonstrated a remarkable improvement in diclofenac uptake compared to the pristine MOF, along with a 5.87-fold increase in initial adsorption rate. Notably, the existence of linker vacancies in a single Zr_mCe_6-mO₈(BTC)_n cornerstone of mixed-metal MOF-808 increased abundant mesopores, decreasing the mass transfer resistance and offering open metal sites. The combined Ce L-edge, Zr K-edge EXAFS, and theoretical calculation using DFT demonstrated that Zr-O-Ce caused asymmetric electron distribution and dramatically facilitated the charge separation abilities during the ligand-to-metal charge transfer (LMCT) mechanism under the irradiation of visible light. The degradation kinetics of ibuprofen increased significantly compared to pristine MOF-808 by the photogenerated hole and hydroxyl radical (9.31 × 10⁻¹⁵ M). Our findings elucidate the mechanism by which multivariate metals incorporation augments the catalytic performance of MOFs for removing pharmaceuticals, providing useful insights for the design of efficient functional catalysts.