Chromium-doped titanium dioxide thin-film photoanodes in visible-light-induced water cleavage

A new method for the synthesis of nanocrystalline anatase Cr-doped TiO2 colloids from nanotubes utilizing the hydrothermal ion-intercalation (HII) method has been devised using hydrothermal treatment in an acidic environment. To investigate the photoelectrochemical reaction that occurs when water is split into H2 and O2 under visible light, a Cr-doped TiO2 thin film served as a model photoelectrode. The photoelectrochemical activity of Cr-doped TiO2 was higher than that of the undoped sample. The photoelectrochemical activity of photoelectrodes increased drastically with increased chromium doping. A red shift in the band gap was induced by Cr doping of TiO2. It was revealed that the Cr-doped TiO2 photoelectrode was able to utilize a wide range of light in the visible region of the spectrum. At high Cr concentrations, the lower photoelectrochemical activity is attributed to the effect of Cr3+ ion recombination and excess Cr3+ ions forming secondary phase Cr2O3.