Enhanced Ethanol Gas Sensing Performance of hexagonal ZnO Nanorods Synthesized via a Novel Reflux Technique

Hexagonal zinc oxide (ZnO) nanorods have significant potential in various solid-state applications, including gas sensors, dye-sensitized solar cells (DSSC), and LEDs. This study investigates the chemiresistive properties of ZnO nanorods synthesized on a glass substrate via a novel reflux technique, focusing on their structural, morphological, and optical characteristics. X-ray diffraction (XRD) analysis confirmed a hexagonal wurtzite crystal structure, with an estimated crystallite size of 12 nm. Scanning electron microscopy (SEM) revealed a uniform hexagonal nanorod morphology, while UV-Visible spectroscopy indicated an optical band gap of 3.0 eV. Additionally, a water wettability test showed a contact angle of 150.3°, confirming the superhydrophobic nature of the ZnO nanorod surface. Gas sensing tests were conducted with various reducing gases—ethanol, propanol, xylene, trimethylamine (TMA), and ammonia (NH₃)—to evaluate the sensor’s response. The ZnO nanorod sensor exhibited enhanced sensitivity to ethanol, with a maximum response of 66% at an optimum operating temperature of 325°C. This superior ethanol sensitivity highlights the promise of ZnO nanorod-based sensors for applications in environmental monitoring and medical diagnostics, such as breath analysis for ethanol detection.