Facile Synthesis of TiO/AgPO Composites with Co-exposed High-energy Facets for Efficient Photodegradation of Rhodamine B Solution Under Visible Light Irradiation

In this study, TiO/AgPO composites based on anatase TiO nanocrystals with co-exposed {101}, {010}/{100}, {001} and [111]-facets and AgPO microcrystals with irregular and cubic-like polyhedron morphologies were successfully synthesized by combining hydrothermal and ion-exchange methods. The anatase TiO nanocrystals with different high-energy facets were controllably prepared hydrothermal treatment of the exfoliated [TiO]/[TiO] nanosheet solutions at desired pH values. The AgPO microcrystal with different morphologies was prepared the ion-exchange method in the presence of AgNO and NHHPO at room temperature, which was used as a substrate to load the as-prepared anatase TiO nanocrystals on its surface and to form TiO/AgPO heterostructures. The apparent rate constant of the pH 3.5-TiO/AgPO composite was the highest at 12.0 × 10 min, which was approximately 1.1, 1.2, 1.4, 1.6, 13.3, and 24.0 fold higher than that of pH 0.5-TiO/AgPO (10.5 × 10 min), pH 7.5-TiO/AgPO (10.2 × 10 min), pH 11.5-TiO (8.8 × 10 min), AgPO (7.7 × 10 min), blank sample (0.9 × 10 min), and the commercial TiO (0.5 × 10 min), respectively. The pH 3.5-TiO/AgPO composite exhibited the highest visible-light photocatalytic activity which can be attributed to the synergistic effects of its heterostructure, relatively small crystal size, large specific surface area, good crystallinity, and co-exposed high-energy {001} and [111]-facets. The as-prepared TiO/AgPO composites still exhibited good photocatalytic activity after three successive experimental runs, indicating that they had remarkable stability. This study provides a new way for the preparation of TiO/AgPO composite semiconductor photocatalysts with high energy crystal surfaces and high photocatalytic activity.