Electrosynthesis of gradient TiO2 nanotubes and rapid screening using scanning photoelectrochemical microscopy

Herein, we report a new approach that allows a fast investigation of the influence of the thickness of a TiO2 photoelectrochemical film. For this we developed a simple anodization method that allows the growth of, in one step, on a single titanium electrode, aligned TiO2 nanotubes with length changing gradually between 0 and 10 mu m. We were able to tune the length of the tubes by controlling the immersion time within the electrolyte during the synthesis. The change of the length of the nanotubes over the entire surface of the electrode requires local probes to measure their properties. Therefore, in order to determine the optimal length of the nanotubes for photoelectrochemical application, the response of these electrodes was locally analysed using Scanning PhotoElectroChemical Microscopy.