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.