Hydrothermally synthesized CuO nanostructures and their application in humidity sensing

The copper oxide (CuO) nanostructures have been successfully synthesized from copper sulfate pentahydrate (CuSO₄.5H₂O) and NaOH as a stabilizing agent using simple hydrothermal chemical route. The prepared samples were characterized using x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and UV-visible spectroscopy. The x-ray diffraction study of CuO nanostructures shows a monoclinic structure with average crystalline size 22 nm as calculated from the Debye-Scherrer’s equation. The hydrothermal technique used for the synthesis of CuO plays an important role in the formation of rod-like morphology. Optical study of CuO nanostructure facilitated estimation of bandgap to be 1.3 eV. The humidity sensing properties of CuO nanostructure are studied at a room temperature. The maximum sensitivity response was found to be 82.03 % which was stable and reproducible. The CuO nanostructures were successfully demonstrated as good candidate for humidity sensing application.