Synthesis of ZnWO4/Ag3PO4: p–n heterojunction photocatalyst with enhanced visible-light degradation performance of RhB

A precipitation process was used to produce Ag 3 PO 4 with an irregular small polyhedral structure and an average size of 200–300 nm. Furthermore, using a simple dissolution precipitation technique, polyhedral Ag 3 PO 4 was successfully deposited on the surface of ZnWO 4 . XRD, SEM, TEM, XPS, UV–Vis DRS, and FT-IR spectroscopy were employed to analyze ZnWO 4 /Ag 3 PO 4 composites. The photocatalytic oxidation ability of composites was assessed using Rhodamine B dye degradation model. The results revealed that ZnWO 4 /Ag 3 PO 4 composite material displayed improved visible-light photocatalytic activity, with 7% ZnWO 4 /Ag 3 PO 4 exhibiting the maximum photocatalytic activity. The degradation rate of RhB was 94.0% after 120 min of visible-light irradiation. Nyquist plot indicates that 7% ZnWO 4 /Ag 3 PO 4 composites show the smallest diameter, suggesting a more effective separation of photogenerated electron–hole pairs and faster interface charge transfer. The photocatalytic activity of ZnWO 4 /Ag 3 PO 4 composites does not deteriorate considerably after four cycles, indicating their high stability. The active species capture tests show that h + and •OH are possible reactive species in the degradation reaction. Finally, the p-n heterojunction mechanism is proved by the discussion of the band structure. This study demonstrates that ZnWO 4 /Ag 3 PO 4 photocatalytic composites can be utilized to degrade contaminants.