Enhanced Visible-Light-Sensitive Two-Step Overall Water-Splitting Based on Band Structure Controls of Titanium Dioxide and Strontium Titanate

Abstract

Visible light-induced two-step overall water-splitting was achieved by combining two types of photocatalysts, which were prepared by introducing foreign elements into rutile titanium dioxide (TiO 2) and strontium titanate (SrTiO 3) with a controlled electronic band structure. Rutile TiO 2 and SrTiO 3 were doped with chromium and tantalum (Cr,Ta-TiO 2) and with rhodium (Rh-SrTiO 3), respectively, to introduce visible-light sensitivity. Under irradiation with only visible light from a 420-nm LED lamp, the simultaneous liberation of hydrogen and oxygen with a molar ratio of ~2:1 was achieved with these two types of photocatalysts in the presence of iodate ion/iodide ion as a redox mediator.