Development of Defect-controlled, Visible-light-responsive Rutile TiO₂ Photocatalysts

Abstract

TiO₂ is a well-known semiconductor photocatalyst, but the wide band-gap restricts its application to solar energy conversion. We demonstrated that tantalum and nitrogen-codoped rutile TiO₂ was an active photocatalyst for water oxidation under visible light. It achieved overall water splitting in combination with a H₂-evolution photocatalyst of SrTiO₃:Rh and an Fe³⁺/Fe²⁺ redox couple even under simulated sunlight. We also found that rutile TiO₂ modified with cobalt hydroxide nanoclusters was capable of harvesting visible light with wavelengths of up to 850 nm, and photocatalyzing water oxidation to produce molecular O₂. To our knowledge, this system provides the first demonstration of a photocatalytic material capable of water oxidation upon excitation by visible light up to such a long wavelength, even with the use of earth-abundant elements only.