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

The occurrence of pharmaceutical and personal care products (PPCPs) in the ambient environment has raised serious concerns. Herein, a dispersed ZnFe 2 O 4 nanoparticle loaded Ag@Ag 2 CO 3 nanorod hybrid (ZnFe 2 O 4 /Ag@Ag 2 CO 3 ) was facile prepared, and used as a solar light driven photocatalyst for the degradation of tetracycline (TC), a typical   PPCPs. The hybrids were characterized by XRD, SEM, EDS, HRTEM, DRS, PL, TRPL, M−H , BET, XPS, ESR and photoelectrochemical testing. The ZnFe 2 O 4 was evenly dispersed on the surface of Ag@Ag 2 CO 3 nanorods of which diameter was about 100 nm. The obtained ZnFe 2 O 4 /Ag@Ag 2 CO 3 composites exhibited high TC degradation efficiency after 150 min Xe light illumination, which was much better than those of pure Ag@Ag 2 CO 3 and ZnFe 2 O 4 . The photodegradation reaction rate constant ( k ) of the optimum ternary photocatalyst (ZnFe 2 O 4 loading 5% wt) increased 4.04 times and 2.48 times than those of pure ZnFe 2 O 4 and Ag 2 CO 3 @Ag, respectively. More importantly, the stability and recovery capacity of the ZnFe 2 O 4 /Ag@Ag 2 CO 3 photocatalyst improved obviously than those of Ag@Ag 2 CO 3 . The reactive oxygen species (ROS) experiment indicated that • OH、h + and • O 2 − involved in the photocatalytic reaction process, and the ROS contributes order was • O 2 − > h + > • OH. The band positions of individual ZnFe 2 O 4 and Ag 2 CO 3 were elucidated via DRUV–Vis spectra and Mott-Schottky plots. Based on the results of ROS experiment and band structure of ZnFe 2 O 4 and Ag 2 CO 3 , it could be inferred that the photocatalytic reaction of ZnFe 2 O 4 /Ag@Ag 2 CO 3 abided by Z-scheme mechanism, that is, Ag acted as the electronic bridge between Ag 2 CO 3 and ZnFe 2 O 4 , and the • OH and • O 2 − were formed on the valence band (VB) of Ag 2 CO 3 and conduction band (CB) of ZnFe 2 O 4 , respectively, and then TC was further oxidized. The sufficient photocatalytic degradation of TC in ambient water revealed that a sunlight-driven ZnFe 2 O 4 /Ag@Ag 2 CO 3 photocatalytic process may be efficiently applied for the remediation of PPCPs contaminated natural waters.