Water splitting over transition metal-doped SrTiO3 photocatalysts with response to visible light up to 660 nm

Abstract

Highly efficient water splitting under visible light irradiation was achieved using Ir, Sb, and Al-codoped SrTiO₃ of a single particulate metal oxide photocatalyst by a solid-state reaction followed by flux treatment using SrCl₂ and loading of a RhCrO_x cocatalyst. The photocatalytic activity was improved by Al₂O₃ addition to the flux treatment, and doping of small amounts of Ir and Sb. It is notable that the water splitting over the photocatalyst proceeded with response to visible light up to 660 nm. This response wavelength is the longest compared with previously reported single particulate visible-light-driven photocatalysts for water splitting. The apparent quantum yield at 420 nm of the optimized photocatalyst was 0.73%. This photocatalyst was active for solar water splitting and gave 0.33% solar-to-hydrogen energy conversion efficiency (STH). Notably, water splitting proceeded giving 0.035% STH under visible light (λ > 440 nm) in a solar spectrum. Additionally, Rh, Ru, and Cr-doped SrTiO₃ photocatalysts were also successfully developed for highly efficient water splitting under visible light irradiation by application of the strategies of small amounts of doping, flux treatment with SrCl₂ with Al₂O₃ addition, and loading of a RhCrO_x cocatalyst.