Water Splitting on Rutile TiO2 -Based Photocatalysts.

Water splitting using a semiconductor photocatalyst with sunlight has long been viewed as a potential means of large-scale H2 production from renewable resources. Different from anatase TiO2 , rutile enables preferential water oxidation, which is useful for the construction of a Z-scheme water-splitting system. The combination of rutile TiO2 with a suitable H2 -evolution photocatalyst such as a Pt-loaded BaZrO3 -BaTaO2 N solid solution enables solar-driven water splitting into H2 and O2 . While rutile TiO2 is a wide-gap semiconductor with a bandgap of 3.0 eV, co-doping of rutile TiO2 with certain metal ions and/or nitrogen produces visible-light-driven photocatalysts, which are also useful as a component for water oxidation in visible-light-driven Z-scheme water splitting. The key to achieving highly efficient water oxidation is to maintain a charge balance of dopants in the rutile, because single doping typically produces trap states that capture photogenerated electrons and/or holes. Here we provide a concise summary of rutile TiO2 -based photocatalysts for water-splitting systems.