Preparation and photocatalytic performance of a magnetically recyclable ZnFe2O4@TiO2@Ag2O p-n/Z-type tandem heterojunction photocatalyst: Degradation pathway and mechanism

The high recombination rate of photoelectron-hole pairs and the difficulty separating the catalyst from the so-lution severely restrict the development of photocatalysis. The construction of heterojunctions and the loading of magnetic carriers are considered to be effective solutions to these two problems. Against this background, a magnetically recoverable ZnFe2O4 @TiO2 @Ag2O heterojunction composite photocatalyst was prepared. Under the optimum preparation conditions, the degradation rate of rhodamine B (RhB) by the composite catalyst under ultraviolet(UV) light reached 98.4% within 40 min; the kinetic constant k was 0.09449 min -1, which was 39.2, 2.0 and 7.8 times those of ZnFe2O4, TiO2 and Ag2O alone, respectively, and the removal rate of total organic carbon (TOC) reached 63.2%. In addition, the catalyst also showed good magnetic recovery performance and reusability. A series of characterization and mechanism research results show that the excellent photocatalytic performance is due to the synergistic effect of the Z-type heterojunction and p-n junction, which promotes the separation and transfer efficiency of photogenerated electron-hole pairs. In conclusion, this work provides new insight into the preparation of magnetically recoverable heterojunction photocatalysts and their application in the degradation of organic pollutants.

Automated summary

A magnetically recoverable ZnFe2O4 @TiO2 @Ag2O heterojunction composite photocatalyst was prepared, which showed high efficiency in degrading organic pollutants. The synergistic effect of the heterojunction and p-n junction improved the separation and transfer efficiency of photogenerated electron-hole pairs.