Flower-Like ZnO Nanorods Synthesized by Microwave-Assisted One-Pot Method for Detecting Reducing Gases: Structural Properties and Sensing Reversibility

Abstract

In this work, flower-like ZnO nanorods (NRs) were successfully prepared using microwave-assisted techniques at a low temperature. The synthesized NRs exhibited a smooth surface and good crystal structure phase of ZnO. The sharp peak of the XRD and Raman spectrum confirmed the high crystallinity of these ZnO NRs with a pure wurtzite structure. The nanorods were ~2 μm in length and ~150 nm in diameter, respectively. The electron diffraction pattern confirmed that the single crystal ZnO nanorods aligned along the [001] plane. The NRs were applied to fabricate a gas sensor for reducing gases such as CH 4 , CO, and H 2 . The sensor showed a good performance and sensitivity toward the target gases. However, its response toward CH 4 and CO was higher compared to H 2 gas. Although the operating temperature was varied from room temperature (RT) up to 350°C, the sensor did not show a response toward any of the target gases in the range of RT-150°C, but dramatic enhancement of the sensor response was observed at 200°C, and up to higher temperatures. This behavior was ascribed to the activity of the smooth surface and the reactivity of surface oxygen species with the targeted gases. The sensor response was measured at various gas concentrations, where the calibration curve was shown. The gas sensing mechanism was described in terms of the reaction of the gases with the transformed oxygen species on the surface of the oxides.

Enhancing the Efficiency of Dye‐Sensitized Solar Cells (DSSCs) by Nanostructured Ag‐doped ZnO Electrodes

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Feasibility of Solar Updraft Towers as Photocatalytic Reactors for Removal of Atmospheric Methane–The Role of Catalysts and Rate Limiting Steps

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A p-n Heterojunction Based Pd/PdO@ZnO Organic Frameworks for High-Sensitivity Room-Temperature Formaldehyde Gas Sensor

“…Moreover, the development of various fast and portable gas sensors were based on varieties of material, such as nanostructures of a metal oxide semiconductor (MOS), especially zinc oxide (ZnO), due to low cost, easy synthesis strategies, and good sensing performance ( Wang et al, 2003 ; Jing and Zhan, 2008 ; Yang et al, 2011 ). Therefore, different methods were employed to synthesize diverse morphology of ZnO nanomaterials, such as nanowires ( Mascini et al, 2018 ), nanoflowers ( Li et al, 2015 ), and nanorods ( Aljaafari et al, 2020 ). On the other side, a high operating temperature is required to activate gas sensing sites ( Huang et al, 2011 ; Wang et al, 2014 ), eliminating the possibility of being integrated with IC circuits or other flexible substrates.…”