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.
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