Photoelectrochemical water splitting on chromium-doped titanium dioxide nanotube photoanodes prepared by single-step anodizing

Abstract Cr-doped TiO 2 nanotubes (Cr–TiO 2 NTs) with different amounts of chromium were obtained directly by the electrochemical anodic oxidation of titanium foils in a single-step process using potassium chromate as the chromium source. The effects of chromium amount in anodizing solution on the morphologies, structure, photoabsorption and photoelectrochemical water splitting of the TiO 2 nanotube array film were investigated. Diffuse reflectance spectra showed an increase in the visible absorption relative to undoped TiO 2 NTs. The photoelectrochemical performance was examined under visible irradiation in 1 M NaOH electrolyte. Photo-electrochemical characterization shows that chromium doping efficiently enhances the photo-catalytic water splitting performance of Cr-doped TiO 2 nanotube samples. The sample (Cr–TiO 2 NTs-1) exhibited better photo-catalytic activity than the undoped TiO 2 NTs and Cr–TiO 2 NTs fabricated using other chromium concentrations. This can be attributed to the effective separation of photogenerated electron–hole upon the substitutional introduction of appropriate Cr amount in to the TiO 2 nanotube structure.