Comparative study of the photocatalytic decolorization of rhodamine B dye by AgI-Ag3PO4 prepared from co-precipitation and ion-exchange methods

摘要

Abstract Photocatalysts in AgI-Ag3PO4 system were prepared from co-precipitation and ion-exchange methods. With an increment of KI concentration, the products prepared from both methods changed from Ag3PO4 to a combination of 3 phases (Ag3PO4, Ag5I2PO4 and AgI), then a mixture of AgI and Q (where Q?=?Ag5I2PO4 (for co-precipitation method) or Ag3PO4 (for ion-exchange method)), and finally to AgI. The preparation method strongly effected on the formation of Ag5I2PO4 in the products. Using the co-precipitation method, Ag5I2PO4 was formed easier than that of ion-exchange method. Product containing high concentration of AgI induced degradation of rhodamine B (RhB) favoring through the N-deethylation process. The dominant mechanism of the RhB degradation for photocatalyst with high Ag3PO4 or Ag5I2PO4 content occurred by the cleavage of chromophore structure of the RhB. Graphical abstract AgI in the sample could adsorb RhB and also induce it to degrade through the N-deethylation process, leading the hypsochromic shift of maximum absorption band with increasing the irradiation time. The interaction between RhB molecules and photogenerated holes at the valence band of Ag3PO4 or Ag5I2PO4 is the cause of the cleavage of chromophore structure of RhB. The competition between these two pathways is strongly influenced by the ratio of AgI:Ag3PO4 in the prepared photocatalyst. Display Omitted Highlights ? The preparation method has a strong effect on the phase composition in the products. ? RhB degraded by N