Rational design of Z-scheme ZnFe2O4/Ag@Ag2CO3 hybrid with enhanced photocatalytic activity, stability and recovery performance for tetracycline degradation

Abstract

The occurrence of pharmaceutical and personal care products (PPCPs) in the ambient environment has raised serious concerns. Herein, a dispersed ZnFe2O4 nanoparticle loaded Ag@Ag2CO3 nanorod hybrid (ZnFe2O4/Ag@Ag2CO3) was facile prepared, and used as a solar light driven photocatalyst for the degradation of tetracycline (TC), a typicalPPCPs. The hybrids were characterized by XRD, SEM, EDS, HRTEM, DRS, PL, TRPL, M−H, BET, XPS, ESR and photoelectrochemical testing. The ZnFe2O4 was evenly dispersed on the surface of Ag@Ag2CO3 nanorods of which diameter was about 100 nm. The obtained ZnFe2O4/Ag@Ag2CO3 composites exhibited high TC degradation efficiency after 150 min Xe light illumination, which was much better than those of pure Ag@Ag2CO3 and ZnFe2O4. The photodegradation reaction rate constant (k) of the optimum ternary photocatalyst (ZnFe2O4 loading 5% wt) increased 4.04 times and 2.48 times than those of pure ZnFe2O4 and Ag2CO3@Ag, respectively. More importantly, the stability and recovery capacity of the ZnFe2O4/Ag@Ag2CO3 photocatalyst improved obviously than those of Ag@Ag2CO3. The reactive oxygen species (ROS) experiment indicated that •OH、h+ and •O2− involved in the photocatalytic reaction process, and the ROS contributes order was •O2− > h+ >•OH. The band positions of individual ZnFe2O4 and Ag2CO3 were elucidated via DRUV–Vis spectra and Mott-Schottky plots. Based on the results of ROS experiment and band structure of ZnFe2O4 and Ag2CO3, it could be inferred that the photocatalytic reaction of ZnFe2O4/Ag@Ag2CO3 abided by Z-scheme mechanism, that is, Ag acted as the electronic bridge between Ag2CO3 and ZnFe2O4, and the •OH and •O2− were formed on the valence band (VB) of Ag2CO3 and conduction band (CB) of ZnFe2O4, respectively, and then TC was further oxidized. The sufficient photocatalytic degradation of TC in ambient water revealed that a sunlight-driven ZnFe2O4/Ag@Ag2CO3 photocatalytic process may be efficiently applied for the remediation of PPCPs contaminated natural waters.