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).