Magnetically separable NiFe2O4/Ag3VO4/Ag2VO2PO4 direct Z-scheme heterostructure with enhanced visible-light photoactivity

BACKGROUND The occurrence of organic contaminants in surface water has drawn great concern in recent years. The construction of a heterostructure has been shown to improve photoactivity by boosting the separation of photogenerated charge carriers. In this work, magnetically separable NiFe2O4/Ag3VO4/Ag2VO2PO4 (NFO/AVO/AVPO) heterojunction photocatalysts were synthesized via a chemical etching method in ammonia solution of different concentrations, using NFO/AVPO as the source material. The magnetic NFO/AVO/AVPO not only endows magnetic recoverability using an external magnetic field, but also possesses a heterojunction, boosting the separation of photoinduced charges. RESULTS Compared with NFO, AVPO and NFO/AVPO, NFO/AVO/AVPO composites as synthesized show improved visible-light photoactivities. At the optimum concentration (0.15 mol L-1) of ammonia solution, the NFO/AVO/AVPO shows 8.5 and 10.7 times improved photodegradation efficiency for methylene blue and imidacloprid than that of pristine NFO/AVPO, respectively. Due to the presence of magnetic NiFe2O4, the NFO/AVO/AVPO can be magnetically separated easily from the photoreaction system using a magnet. The improved photoactivity can be attributed to the formation of a direct Z-scheme heterojunction, which boosts the separation of photoinduced electron-hole pairs. CONCLUSION This work not only opens up a new method to fabricate heterojunction photocatalysts, but also paves the way for designing advanced magnetically separable photocatalysts with improved photoactivity. (c) 2021 Society of Chemical Industry (SCI).

Automated summary

In this study, magnetically separable NiFe2O4/Ag3VO4/Ag2VO2PO4 (NFO/AVO/AVPO) heterojunction photocatalysts were successfully synthesized via a chemical etching method. The unique heterojunction structure not only allows for easy magnetic recovery, but also significantly enhances the photoactivity, particularly in terms of photodegradation efficiency for methylene blue and imidacloprid.