Water effect on the surface morphology of TiO2 thin film modified by polyethylene glycol

► TiO2 porous thin film is fabricated using polyethylene glycol 6000 (PEG-6000) as a template. ► The water molecules provide locations for the aggregation of PEG-6000, and it is demonstrated by the phase diagrams of AFM. ► The water content has an influence on the surface structure and the thin film thickness. ► The TiO2 thin film has the best photocatalytic activity when the ratio of water to Ti precursor is 2.