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

• Cr-doped TiO2 nanotube layers (Cr–TiO2NTs) were synthesized by anodizing of titanium in a single-step process.
• Photoelectrochemical water splitting of Cr–TiO2NTs is higher than that of pure TiO2 nanotubes (TiO2NTs).
• Quantity effect of chromium in these composite for photoelectrochemical water splitting is investigated.
• Maximum hydrogen production of 37 μL/cm2 after 240 min is obtained.

Cr-doped TiO2 nanotubes (Cr–TiO2NTs) 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 TiO2 nanotube array film were investigated. Diffuse reflectance spectra showed an increase in the visible absorption relative to undoped TiO2NTs. 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 TiO2 nanotube samples. The sample (Cr–TiO2NTs-1) exhibited better photo-catalytic activity than the undoped TiO2NTs and Cr–TiO2NTs 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 TiO2 nanotube structure.

Current–potential curves with chopped light measured in 1 M NaOH with a scan rate of 5 mV s−1 for the different samples.Figure optionsDownload as PowerPoint slide