Cocatalytic Effect of SrTiO3 on Ag3PO4 toward Enhanced Photocatalytic Water Oxidation

Abstract

Ag 3 PO 4 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 SrTiO 3 /Ag 3 PO 4 composite photocatalysts was constructed by introducing SrTiO 3 (with a less positive valence band minimum) to Ag 3 PO 4 and was synthesized by two consecutive hydrothermal processes. The obtained photocatalysts were systematically characterized by XRD, SEM, BET, UV–vis, etc., showing that SrTiO 3 /Ag 3 PO 4 composites were formed by coating SrTiO 3 onto a Ag 3 PO 4 polyhedron. Photocatalytic O 2 evolution results demonstrated that a small amount of SrTiO 3 brought about significant enhancement of photocatalytic activity of Ag 3 PO 4 and that the apparent quantum yield at 420 nm reached 16.2% with a molar ratio of SrTiO 3 to Ag 3 PO 4 equal to 1/20, which led to the fact that SrTiO 3 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.