As photocatalyst the low recombination efficiency and efficient utilization of photoelectron-holes are crucial for high photodegradation efficiencies, rapid disinfection in water catalytic purification. Herein, a sandwich-structured Z-scheme Silver sulfide/ferroferric oxide/silver metavanadate graphene microtube composite photocatalyst (Ag2S/Fe3O4/AgVO3@GM) was successfully prepared by a novel strategy using capillary effect combined with hydrothermal method. In this sandwich-structured composite, Ag2S, Fe3O4 and AgVO3 are anchored in the inner, middle and outer layers of graphene microtube, respectively, which construct a Z-scheme system with spatially separated microtopography. The Fe3O4 nanoparticles (NPs) in the middle of graphene microtube layer not only help the composite photocatalyst recycle due to their superparamagnetism but also serve as the redox mediator in the Z-scheme system to collect and consume the electrons and holes from AgVO3 and Ag2S on inner/outer layer graphene microtube, which can effectively facilitate the separation rate of photo-generated charge carriers, and generate more activity radicals. Moreover, the spatially separated graphene microtube micromorphology can significantly promote the mass transport efficiency in photocatalytic reaction. The obtained Ag2S/Fe3O4/AgVO3@GM shows remarkable performance for photocatalytic degradation (towards methyl orange (MO) about 98% within 30 min) and disinfection (100% Escherichia coli (E. coli) inactivation) and high cyclic stability.
Keywords: Charge transfer; Oxidation-reduction mediators; Sandwich graphene microtubes; Spatially separated photocatalysts; Z-scheme heterostructure.
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