Asymmetric Electron Distribution of CE (Iv)/Zr (IV) Cornerstones in Multivariate Mof-808: Unlocking Improved Activation and Micropollutants Removal

Abstract

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(Zr3.84Ce2.04) 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 ZrmCe6-mO8(BTC)n cornerstone of mixed-metal MOF-808 increased abundant mesopores, decreasing the mass transfer resistance and offering the 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 (h+) and hydroxyl radical (•OH). 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.

Keywords: Pharmaceutical and personal care products, Adsorption, Visible-light, Defects, metal-organic framework, photodegradation