Cocatalytic Effect of SrTiO₃ on Ag₃PO₄ toward enhanced photocatalytic water oxidation

Ag₃PO₄ has been reported to be an excellent photocatalyst for O₂ evolution from aqueous solution, which makes it a promising candidate for designing a Z-scheme water-splitting system. In this work, in order to further improve the photocatalytic activity, a series of SrTiO₃/Ag₃PO₄ composite photocatalysts was constructed by introducing SrTiO₃ (with a less positive valence band minimum) to Ag₃PO₄ and was synthesized by two consecutive hydrothermal processes. The obtained photocatalysts were systematically characterized by XRD, SEM, BET, UV-vis, etc., showing that SrTiO₃/Ag₃PO₄ composites were formed by coating SrTiO₃ onto a Ag₃PO₄ polyhedron. Photocatalytic O₂ evolution results demonstrated that a small amount of SrTiO₃ brought about significant enhancement of photocatalytic activity of Ag₃PO₄ and that the apparent quantum yield at 420 nm reached 16.2% with a molar ratio of SrTiO₃ to Ag₃PO₄ equal to 1/20, which led to the fact that SrTiO₃ could serve as cocatalyst for water oxidation providing both accelerated electron-hole separation by band gap alignment and more active sites by enlarged surface area.