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 (lambda > 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, N-2 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 O-2 center dot(-) 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. (C) 2016 Elsevier B.V. All rights reserved.