The active roles of ZIF-8 on the enhanced visible photocatalytic activity of Ag/AgCl: Generation of superoxide radical and adsorption

For detecting the active roles of ZIF-8 in composite photocatalyst, a novel Ag/AgCl/ZIF-8(50%) composite photocatalyst was designately prepared by anchoring Ag/AgCl nanoparticles on the surface of ZIF-8 with 50% content. The adsorption and photocatalytic performance of Ag/AgCl/ZIF-8(50%) were conducted by removal of Rhodamine B (RhB) from aqueous solution under dark and visible light irradiation (λ > 420 nm). The experimental results showed that the as-synthesized Ag/AgCl/ZIF-8(50%) exhibited higher photocatalytic activity than Ag/AgCl. The XRD, TEM, FTIR, DRS, VB XPS, ESR, N2 adsorption isotherms and active species trapping experiments were used to characterize the performance of the composite photocatalyst. We found that the ZIF-8 in composite photocatalyst not only has the adsorption ability for RhB by its large specific area, but also has the ability for the formation of O2·− by an appropriate position of conduction band (CB). A reasonable reaction mechanism with a new perspective on the composite photocatalyst of Ag/AgCl/ZIF-8(50%) was proposed. This insight on the active roles of ZIF-8 in Ag/AgCl/ZIF-8(50%) may open a window for the use of MOF material in photocatalytic field.