Characterization and photocatalytic activity of TiO2 thin films prepared by sol-gel method for NOx degradation

[Display omitted] •TiO2 thin films were prepared by sol-gel dip-coating method.•The effect of the sol viscosity and withdrawal speeds from sols on the coating thickness was investigated.•The number of layers influenced the surface topography and the photocatalytic activity of TiO2 coatings.•The obtained TiO2 layers were characterized by very good adhesion to the substrate.•TiO2 thin films have efficient photocatalytic activity. Titanium dioxide (TiO2) thin film photocatalysts for the elimination of nitrogen oxides (NOx) were prepared by the dip-coating process using the sol–gel method. To prepare the sols, titanium (IV) butoxide (Ti(OBu)4), diethanolamine (DEA), butanol, and HCl were chosen. The TiO2 coatings were prepared using sols with varying volume ratios of Ti(OBu)4:DEA:Butanol. Additionally, three withdrawal speeds from the sol were employed. Subsequently, the TiO2 thin films were sintered at 500 and 700 °C. The obtained thin films were characterized using SEM to determine thickness, AFM to determine roughness, and the Step 500 platform for the adhesion test. NOx was found to be efficiently eliminated by TiO2 thin film photocatalyst. It is possible to obtain a TiO2 coating that is capable of degrading 300 ppb of NO in real time under specific conditions: a relative humidity of 30 %, a UV intensity of 20 W/m2, a gas flow rate of 1 dm3/min.