Enhanced Visible Light-driven Photocatalytic Activities of Ag3PO4 Modified Electrochemically Anodized TiO2 Nanotube Arrays

In this work, the Ag3PO4/TiO2 nanotube arrays (TNTAs) composite photocatalysts were successfully prepared by a facile chemical impregnation method, and their photocatalytic properties were investigated. It was found that the TNTAs sample, which was prepared by electrochemical anodization, consisted of a highly ordered array of nanotubes with a diameter of about 110 +/- 10 nm. For the Ag3PO4/TNTAs sample, Ag3PO4 nanoparticles (ca. 2 similar to 8 nm) were uniformly distributed on the surface of TNTAs. The TNTAs sample mainly absorbed ultraviolet light and rarely visible light. In contrast, the Ag3PO4/TNTAs sample absorbed much stronger visible light while maintaining ultraviolet light absorption. More importantly, the visible light photocatalytic activity of Ag3PO4/TNTAs for rhodamine B (RhB) degradation was much better than that of TNTAs, and the photodegradation rate constant of Ag3PO4/TNTAs was about 2.6 times that of TNTAs. The improved photocatalytic activity of Ag3PO4/TNTAs could be attributed to the following two aspects: (1) the loading of Ag3PO4 could improve the visible light absorption performance and spectral utilization efficiency of TNTAs; and (2) the heterojunctions formed between Ag3PO4 and TNTAs could be beneficial for the separation and transfer of photogenerated charges, which would greatly improve the photocatalytic performance of TNTAs.