A method for modifying the surface properties of ZnO nanowires deposited as thin films on various substrates

In this paper, we demonstrate the approach of obtaining an array of ZnO nanowires, deposited as a thin film on different substrates (glass, Si plate, foil, etc.). As-obtained ZnO thin films have a hydrophilic state with water droplets with a contact angle value of 0°. Treatment of ZnO thin films with H2 gas (under specific conditions) changes the state of ZnO thin films to a hydrophobic state with a roll-off angle with the droplet of water 60°. However, ZnO thin films treatment with O2 gas makes ZnO thin films go back to a hydrophilic state. This operation can be repeated in a cycle manner using H2 and O2 gases to approach different states of ZnO thin films such as hydrophilic and hydrophobic. Thin films of ZnO nanowires can be deposited on a variety of substrates such as glasses, metals, and polyamides.