Design of Experiments (DOE) for synthesis of nanotubular structured electrodes

Vertically nanotubular layered TiO2 based electrodes were obtained by electrochemical anodization of Ti foils in ammonium fluoride organic electrolytes. The effect of the anodization bath composition on their photo-electrocatalytic performance was investigated. The organic solvent (S), the fluoride concentration (F) and the water content (W) in the bath were selected as influent parameters, which were varied at two levels in a set of experiments organized by means of the design of experiments technique (DOE). Aspect ratio of the nanotubes, photocurrent measured both at UV and near visible light were adopted as objective functions in order to evaluate the performances of the samples. Single and combined effects of the parameters on the objective functions have been measured. The results indicate that the water content has no effect on the aspect ratio of the samples; however its content in the organic solvent plays a crucial role in the photocatalytic performances.