Abstract

The effects of preparation methods, calcination times, and La doping concentrations on the crystallinity, visible light absorption, and photocatalytic water splitting performance of Rh- and La-codoped SrTiO3 (SrTiO3:La/Rh) were investigated. Applying a two-step solid state reaction in which SrTiO3 acted as a perovskite-type host produced core/shell structured SrTiO3:La/Rh, the surface of which was enriched with the dopants. La doping suppressed the formation of oxygen vacancies and inactive Rh4+ species. Under visible light irradiation (λ > 420 nm), SrTiO3:La/Rh exhibited 3.5 and 3.8 times higher rates of H2 evolution in an aqueous methanol solution and during redox-free Z-scheme overall water splitting in combination with Ir/CoOx/Ta3N5, respectively, compared to SrTiO3:Rh. The solar-to-hydrogen efficiency of the Z-scheme system as measured under illumination with simulated sunlight (AM1.5G) was found to have improved by a factor of 3.