Cocatalytic Effect of SrTiO3 on Ag3PO4 toward Enhanced Photocatalytic Water Oxidation

Ag3PO4 has been reported to be an excellent photocatalyst for O-2 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 O-2 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 rim 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.