Hydrophobic photocatalytic composite coatings based on nano-TiO2 and fluorinated ethylene propylene prepared by electrostatic spraying

In this study, a repeatable and environmentally friendly method was utilized to prepare a hydrophobic surface with photocatalytic features can be applied on large surfaces without the complexity of the chemical methods. In this regard, titanium dioxide nanoparticles and fluorinated ethylene propylene (FEP) resins were applied on an aluminum substrate using two methods of layer-by-layer and mixing through the electrostatic spraying approach. The prepared films were analyzed by scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Differential Reflectance Spectroscopy (DRS), energy-dispersive X-ray spectroscopy (EDS), and water contact angle (WCA) measurements. The photocatalytic activities were also explored by examining the degradation of oleic acid and four organic dyes under UV irradiation. This method led to formation of a hydrophobic photocatalytic surface with static contact angles above 130⁰. In the layer-by-layer method, the sample with one layer of titanium dioxide and three layers of FEP exhibited better hydrophobicity and photocatalytic performance. In the mixing method, better hydrophobicity and photocatalytic performance were observed in the one containing 10 wt% TiO2.