Construction of visible-light-responsive metal-organic framework with pillared structure for dye degradation and Cr(VI) reduction

A water-stable mixed-linker metal-organic framework (MOF) was rationally synthesized using a controllable pillared-layer method. The prepared Co(II)-MOF shows wide-range absorption in the visible light region due to the incorporation of highly conjugated anthracene-based bipyridine ligand. Experiments suggest that the MOF is highly efficient for the photoreduction of toxic Cr(VI) ions in water under visible light. Important issues affecting photocatalytic performance, such as the influence of pH and the control of electron-hole separation by scavenger, were carefully examined. Beyond Cr(VI) ions, we also explored the photocatalytic degradation performance of the MOF using a persistent azo dye as a model substrate, where H2O2-involved advanced oxidation process was applied. Control experiments suggest that the introduction of environmentally benign H2O2 significantly enhances the degradation performance due to the generation of reactive hydroxyl radicals. The study not only demonstrates the great feasibility of the preparation of a new MOF photocatalyst through a controllable pillared-layer method, but also reveals that rational functionalization of ligand in the MOF is convenient for achieving desirable applications.