Flux-mediated doping of SrTiO3 photocatalysts for efficient overall water splitting

Abstract

SrTiO₃ is a photocatalyst that is well known for its activity for the overall water splitting reaction under UV light irradiation. In this study, the effects of SrCl₂ flux treatments and Al doping on the photocatalytic properties of SrTiO₃ were investigated. The SrTiO₃, which showed an apparent quantum efficiency of 30% at 360 nm in the overall water splitting reaction, the highest value reported so far, was prepared by SrCl₂ flux treatments in alumina crucibles. Scanning electron microscopy and X-ray diffractometry revealed that the flux-treated SrTiO₃ consisted of well-crystalline particles with a cubic shape reflecting the perovskite-type structure. Inductively coupled plasma optical emission spectroscopy revealed that Al ions from the alumina crucibles were incorporated into the SrTiO₃ samples. The SrTiO₃ that was treated with SrCl₂ flux in Al-free conditions showed a marginal improvement in photocatalytic activity despite the high crystallinity and the clear crystal habit. Doping SrTiO₃ with Al improved the photocatalytic activity even without SrCl₂ treatment. These results suggested that Al doping was a principal factor in the dramatic improvement in the water splitting activity of the flux-treated SrTiO₃. The effects of flux treatments and Al doping on the morphology and water splitting activity of SrTiO₃ were discussed separately.