Scaling up anodic TiO2 nanotube layers – Influence of the nanotube layer thickness on the photocatalytic degradation of hexane and benzene

•TiO2 nanotube layers of different thicknesses were prepared on large Ti foils.•The macroscopic area of nanotube coverage on Ti is the largest ever ≈ 100 cm2.•Homogenous TiO2 nanotube layers were achieved on the whole macroscopic area.•TiO2 nanotube layers were used for gas phase photocatalysis under ISO standards.•Excellent results for the photodegradation of hexane and benzene were achieved. In this work, the preparation of homogenous TiO2 nanotube (TNT) layers with different thicknesses via anodization on Ti substrates with a large geometrical area of two times 5 cm x 10 cm (i.e. both sides of the Ti substrate) is shown for the first time. TNT layers with four different thicknesses of ∼0.65 µm, ∼1 µm, ∼7 µm, and ∼14 µm were prepared with excellent conformality and homogeneity over the anodized area. These TNT layers were successfully employed as photocatalysts for the degradation of hexane and benzene as model compounds in the gas phase under ISO standards, showing an increase of the conversion for both model compounds with the TNT layer thickness. While a stable hexane conversion was observed for all TNT layers during the measuring time of three hours, in case of benzene degradation an initial conversion decrease was monitored before the conversion stabilized. Despite this trend, SEM and XPS analyses did not reveal any significant amount of reaction products on the TNT layer surface. [Display omitted]