Tuning the surface morphologies of ZnO nanofilms for enhanced sensitivity and selectivity of CO2 gas sensor

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2023-02, Vol.129 (2), Article 115
• Main Authors: Taha, T. A., Saad, Rana, Zayed, Mohamed, Shaban, Mohamed, Ahmed, Ashour M.
• Format: Article
• Language: English
• Subjects: Ammonia; Applied physics; Carbon dioxide; Characterization and Evaluation of Materials; Condensed Matter Physics; Crystallites; Deposition; Emission analysis; Field emission microscopy; Gas sensors; Machines; Manufacturing; Materials science; Nanorods; Nanostructure; Nanotechnology; Optical and Electronic Materials; Physics; Physics and Astronomy; Preferred orientation; Processes; Room temperature; Scanning electron microscopy; Selectivity; Sensitivity enhancement; Surfaces and Interfaces; Thin Films; Wurtzite; X-ray diffraction; Zinc oxide
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-023-06387-6

In this work, ZnO has been synthesized with a variety of nanomorphologies, including nanorods (NRs), nanodiscs (NDs), and nanorods/nanodiscs (NRs/NDs), to enhance CO 2 gas detection at room temperature. The ZnO nanostructures were made by combining the successive ionic layer adsorption and reaction (SILAR) strategy and the chemical bath deposition (CBD) method. The time of CBD varied from 6 to 12 h. Several techniques, including X-ray diffraction (XRD) spectroscopy, energy-dispersive X-ray (EDAX) spectrometry, optical spectrophotometer, and field emission scanning electron microscopy (FE-SEM), were used to investigate the manufactured ZnO nanostructures. The FE-SEM demonstrates that by increasing the deposition period of CBD from 6 to 12 h, the shape of ZnO nanostructures changed from NRs/NDs to NDs. According to the XRD, all ZnO nanostructured samples exhibit hexagonal wurtzite structures with (002) preferred orientation. Additionally, the crystallite size along orientation (002) increases from 63 to 65 nm as the deposition duration increases from 6 to 12 h. The bandgap of ZnO was reduced from 3.62 to 3.31 eV. When the deposition time is increased from 6 to 12 h, the sensitivity increases from 8.46 to 28.7%, the detection limit rises from 4.65 to 9.95 SCCM, and the limit of quantification rises from 15.52 to 33.16 SCCM. Moreover, the ZnO @ 12 h sensors has excellent selectivity as well since it reacts to CO 2 with a higher response sensitivity than it does to other gases like hydrogen and ammonia.