Construction of defective Zeolitic Imidazolate Frameworks with improved photocatalytic performance via Vanillin as modulator

Abstract

This manuscript presents a synthesis strategy for regulating both the steric property (ligand vacancy) and electronic property (metal valence) of coordinatively unsaturated sites (CUS) in the Zeolitic Imidazolate Frameworks (ZIFs) via vanillin (VAN). VAN molecule involved in the construction of ZIF-67 crystal structure can replace some of the original ligands via competition coordination, and create defect structure and mesopores in ZIF-67 structure. Meanwhile, the aldehyde group in VAN can reduce part of the trivalent cobalt on the surface to divalent cobalt, which is conducive to the adsorption of reactive species in the photocatalytic water splitting process. Moreover, the defective ZIF-67 exhibits favorable modified properties for photocatalysis, including improved porosity, narrow band gaps, enhanced light absorption and carrier separation ability. Compared with other methods using monobasic acid as a regulator, VAN can simultaneously create ligand vacancy, mesopore and more Co2+ sites in MOFs, which may be a more promising method for preparing photocatalysts with excellent performance.