Enhancing photocatalytic activity via formation of heterojunctions introduced through postmetalation of metal organic frameworks with silver ions

Abstract The postmetalation of silver in zinc and manganese-based metal–organic frameworks (MOFs) represents a versatile and efficient approach for enhancing the degradation of methylene blue (MB) pollutant in aqueous environment. In the present study, zinc, manganese, and their bimetallic MOFs are synthesized using the solvothermal method. Subsequently, silver ions are incorporated into the synthesized MOFs. A suite of characterization techniques is employed to analyze the resulting material. Among the three silver loaded MOFs, Ag-mixed bimetallic MOF (Ag-BM) exhibits the least band gap of 2.28 eV, possessing a greater propensity for light absorption. The particle size of Ag-BM lies in the nanometer range, and it possesses the largest surface area. X-ray diffraction depicts the successful integration of Ag into MOF structure. The synthesized samples are used for degrading MB. Ag-BM outperforms the other MOFs in decomposing MB, with a degradation percentage of 91.8% in 120 min. The degradation process follows the first-order kinetics depicting that the rate of degradation positively correlates with the dye concentration remaining in the solution. Employing a reactive species quenching experiment with scavengers, hydroxyl radicals were identified as the principal active species responsible for MB degradation by Ag-BM.