Photoactive hetero-structures based on SnO2, TiO2 and CuInS2 were prepared by robotic spray pyrolysis with optimized deposition parameters. The samples containing metal oxides have uniform and homogeneous surfaces with granular morphologies. The insertion of a CuInS2 layer supports the development of aggregates with different shapes and sizes (0.1-1 mu m). The samples have a surface energy governed by the polar component, outlining the hydrophilic behaviour. According to their band gap, the metal oxides layers absorb mostly in the UV spectral region; by adding the narrow band gap CuInS2 there is a broadening of the spectral range towards Vis, from a maximum of 400 nm (for the samples containing SnO2 and TiO2) up to 700 nm. Additionally, the components of the photoactive hetero-structure have suitably positioned energy bands allowing improved charge carrier separation and mobility. Consequently, the samples show UV-Vis photocatalytic properties outlined in air decontamination, for acetaldehyde removal. (C) 2017 Elsevier Inc. All rights reserved.