Solar photochemical–thermal water splitting at 140 °C with Cu-loaded TiO2

Abstract

Metal oxide based solar thermal water splitting is a promising approach for using solar energy to produce H₂ and O₂. The normal protocol employed for this process involves thermal reduction of a metal oxide (MO_x) at around 1500 °C to produce the reduced form of the metal oxide (MO_x−δ) and O₂. This step is followed by steam treatment of MO_x−δ at around 1000 °C to yield MO_x and H₂. Owing to the need to use high temperatures, the traditional approach has several important drawbacks. In a study designed to improve this process, we found that Cu-loaded TiO₂ (Cu/TiO₂) effectively expels O₂ upon irradiation with AM 1.5 1 Sun solar simulated light and that treatment of the reduced form of the reduction product Cu/TiO_2−δ with steam at 140 °C generates H₂. This new approach, termed as solar photochemical–thermal water splitting, has the potential to become an important method for converting solar energy into chemical energy.