Effect of thickness and cracking phenomena on the photocatalytic performances of Ti/TiO2 photoanodes produced by dip coating

Photoanodes for water-splitting applications were produced by coating acid-treated Ti slabs using an aqueous dispersion of TiO2, polyvinyl alcohol and glycerol. Such components were adjusted to achieve a lower viscosity at a 10 s(-1) shear rate, considered as representative of the dip-coating application, for the sake of reducing the final coating thickness while increasing its quality. A correlation was found between the thickness of the oxide layer and the percentage of area occupied by the crevices, which appeared, during the thermal treatment, as an effect of the liquid phase removal. Also, the adhesion appeared to be strongly related to the cracking phenomena, since less cracked samples withstood much lower weight losses during the adhesion tests. The lower adhesion of thicker coatings was found to affect the photo-catalytic performances of the photoanodes, showing lower photocurrents and efficiencies when compared with thinner ones.