Superhydrophobicity and enhanced UV stability in vertically standing indium oxide nanorods

Here, we report the emergence of superhydrophobic wetting behavior and enhanced UV stability of indium oxide (IO) nanorods due to their vertical alignment. Both randomly distributed and vertically aligned IO nanorods were synthesized via chemical vapor deposition (CVD) method. Our results reveal that the static water contact angle (θ) shows a significant dependence on the alignment of the nanorods. The randomly distributed IO nanorods shows θ value of 133.7° ± 6.8° whereas for vertically aligned IO nanorods θ was found to be 159.3° ± 4.8°. Interestingly, continuous UV light illumination for 30 min exhibited the change in contact angle (Δθ) of about 41° for vertically aligned IO nanorods whereas randomly distributed IO nanorods become hydrophilic with a dramatic change in θ value of 108°. The superhydrophobicity of vertically aligned IO nanorods and their enhanced UV stability were discussed by comparing the effective solid fraction at solid-liquid interface and the reactivity of surface crystallographic planes. The superhydrophobic surface of aligned vertically standing IO nanorods along with its resistance against photoinduced wetting transition make them suitable for electronic devices with reduced surface discharge even at relatively high humidity level.