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 H 2 production from renewable resources. Different from anatase TiO 2 , rutile enables preferential water oxidation, which is useful for the construction of a Z‐scheme water‐splitting system. The combination of rutile TiO 2 with a suitable H 2 ‐evolution photocatalyst such as a Pt‐loaded BaZrO 3 –BaTaO 2 N solid solution enables solar‐driven water splitting into H 2 and O 2 . While rutile TiO 2 is a wide‐gap semiconductor with a bandgap of 3.0 eV, co‐doping of rutile TiO 2 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 TiO 2 ‐based photocatalysts for water‐splitting systems.