Charge separation enhancement of triple-phase Ag3PO4-AgI-ZnO heterojunction for dye photodegradation

Abstract

Pristine ZnO (PC1), AgI (PC2), Ag 3 PO 4 (PC3), and mixed system polyvinyl alcohol (PVA)-assisted AgI-ZnO-Ag 3 PO 4 (PC4) photocatalysts were prepared for the degradation of synthetic methylene blue (MB) dye under visible light. The prepared pristine and nanocomposite photocatalysts were characterized by advanced techniques. HR-TEM finding indicates the intimate contact of PC3 and PC2 with PC1. The combination of PC3 and PC2 with PC1 exhibited a reduced the band gap 2.41 eV and increased surface area of 100.11 m 2 /g, respectevely. The photocatalytic activities of the synthesized materials over MB were tested. A 47 %, 53 %, 62 %, and 98 % of MB degradation efficiencies were achieved for PC1, PC2, PC3, and PC4, respectively. Besides, the PC4 nanocomposite exhibited excellent photocatalytic activity compared to others. This catalytic improvement could be due to the cumulative effect of the different phases. The catalytic potential of the PC4 nanocomposite was 98 %. The stability and reusability of the PC4 nanocomposite were studied for four cycles where the XRD analysis showed almost the same phases before and after reuse were observed. Furthermore, a potential photocatalytic mechanism for the degradation of methylene blue has been put forth, which could provide stable Z -scheme heterojunctions using the pristine photocatalysts.