From nanoparticles, nanorods to nanowalls: preparation and analysis of ZnO using hydrothermal approach for hydrophobic and UV photodetector applications

This work investigates the synthesis of ZnO nanostructures with various aspect ratios, such as nanoparticles (NPs), nanorods (NRs), and nanowalls (NWs), by controlling the hexamethylenetetramine (HMT) concentrations via a hydrothermal approach for UV detectors and hydrophobic surfaces. The FE-SEM images revealed that the surface morphology of zinc oxide NPs, NRs, and NWs was well aligned and dispersed throughout the glass substrate. Hexagonal wurtzite ZnO was confirmed using X-ray diffraction (XRD). Apparently, rods and walls where growth well alignment highly reflect the oriented (002) plane onto the glass substrate, as depicted in FE-SEM analysis. Current–time (I–T) measurements verified the photodetector's performance and revealed a significant photocurrent enhancement under 365 nm UV light, reaching 45 μA for the nanorods sample 1:0.5, achieving a 96% sensitivity, the highest of all samples tested. In addition, the vertical alignment of the 1:0.25 ZnO NRs enabled superhydrophobicity, resulting in a 162.40° contact angle. As a result, these findings confirm the value of the hydrothermal route for preparing different shapes of ZnO for advanced applications such as self-cleaning and UV detector.