SrTiO3 nanosheets decorated with ZnFe2O4 nanoparticles as Z-scheme photocatalysts for highly efficient photocatalytic degradation and CO2 conversion

Nanocomposite has attracted widespread attention for efficiently utilizing solar energy and improving conver-sion efficiency during wastewater purification and solar fuels evolution. In this study, Z-scheme ZnFe2O4-SrTiO3 nanocomposite was prepared and used as photocatalysts for tetracycline hydrochloride (TCH) degradation and CO2 conversion. The as-obtained ZnFe2O4-SrTiO3 system achieved drastically enhanced TCH degradation effi-ciency up to 84.56 % with respect to pure ZnFe2O4(13.81 %) and SrTiO3(49.66 %) under visible light irradiation. The influences of ZnFe2O4 content and co-existing ions on the photodegradation activities were investigated. In addition, ZnFe2O4-SrTiO3 nanocomposite exhibited outstanding CO2 photoreduction activity, the CO and CH4 evolution rate were 8.24 mu mol/g/h and 2.51 mu mol/g/h, which was 2.5 and 6.4 times higher than that observed for SrTiO3, respectively. The reinforced photocatalytic TCH degradation and CO2 conversion activities are mainly attributed to the obviously enhanced utilization of solar energy and the dramatically boosted electron-hole pair separation efficiency through a Z-scheme charge transfer model. In addition, a possible photocatalytic enhancement mechanism of ZnFe2O4-SrTiO3 nanocomposite is proposed in the light of trapping experiments, ESR and DFT calculations. Our studies implies that ZnFe2O4-SrTiO3 nanocomposite are expected to effectively realize wastewater purification and CO2 reduction to renewable solar fuels.