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

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ABSTRACT

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.

Significance of the Study:

The study highlights the superior ethanol gas sensing capabilities of hexagonal ZnO nanorods synthesized via a novel reflux technique. The findings demonstrate that ZnO nanorods offer enhanced sensitivity, selectivity, and stability, making them highly suitable for environmental monitoring and breath analysis applications. Additionally, the superhydrophobic nature of the ZnO surface minimizes contamination, improving sensor durability. The research contributes to the development of cost-effective, high-performance gas sensors, paving the way for advancements in industrial safety, healthcare diagnostics, and portable ethanol detection devices.

Summary of the Study:

This study explores the ethanol gas sensing performance of hexagonal ZnO nanorods synthesized on a glass substrate using a reflux technique. Structural analysis confirmed a hexagonal wurtzite crystal structure with a 12 nm crystallite size, while SEM revealed uniform nanorods. The sensor exhibited a maximum ethanol response of 66% at 325°C. With an optical band gap of 3.0 eV and superhydrophobicity, the ZnO nanorods demonstrated high selectivity and durability, making them promising candidates for real-world gas sensing applications.