Enhanced photocatalytic activity of Ag/ZnO@ZIF-C with core-shell structure and multiple catalytic sites

Abstract

Metal-organic frameworks (MOFs) are with extensive attention for environmental remediation due to their various modification and high density of active sites. Herein, a series of Ag/ZnO@ZIF-C with core-shell structure and graphene carbon (C) acts as a sandwich bridge were designed as a photocatalyst, accelerating the interfacial charge transfer rate between Ag and ZnO. Photocatalytic activities of Ag/ZnO@ZIF-C is remarkably improved toward rhodamine B (RhB) under UV irradiation, i.e., the degradation rate by Ag/ZnO@ZIF-C (20 wt%) is 2.27 times than that of P25. RhB molecules were simultaneously photodegraded at multiple sites, including N-site de-ethyl, conjugate structure and benzene ring. The photocatalytic upgrading performance was recognized to the synergetic interface between ZnO@ZIF-C and Ag nanoparticles (NPs) with effective separation and suppressed the recombination of electrons and holes. It is suggesting that the electrons in the valence band (VB) of ZnO are excited to the conduction band (CB) and transferred to Ag NPs through the ZIF-C layer, then react with adsorbed oxygen to create superoxide radicals and degrade RhB into small molecules. After a five-consecutive operation, its photocatalytic efficiency by Ag/ZnO@ZIF-C (20 wt%) still maintains at 95.11 %. This work provides a promising method for the rational design of high-performance carbon doped photocatalysts for environmental remediation.