Metal Oxide Nanostructure-Based Gas Sensor for Carbon Dioxide Detection (original) (raw)
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Nanostructured SnO2–ZnO composite gas sensors for selective detection of carbon monoxide
Beilstein Journal of Nanotechnology, 2016
A series of SnO2–ZnO composite nanostructured (thin) films with different amounts of SnO2 (from 0 to 50 wt %) was prepared and deposited on a miniaturized porous alumina transducer using the sol–gel and dip coating method. The transducer, developed by our research group, contains Au interdigital electrodes on one side and a Pt heater on the other side. The sensing films were characterized using SEM and AFM techniques. Highly toxic and flammable gases (CO, CO2, CH4, and C3H8) were tested under lab conditions (carrier gas was dry air) using a special gas sensing cell developed by our research group. The gas concentrations varied between 5 and 2000 ppm and the optimum working temperatures were in the range of 210–300 °C. It was found that the sensing performance was influenced by the amount of oxide components present in the composite material. Improved sensing performance was achieved for the ZnO (98 wt %)–SnO2 (2 wt %) composite as compared to the sensors containing only the pristine...
Applied Physics A, 2019
Zinc oxide (ZnO) nanorods prepared by a simple hydrothermal method. The characterization of the sample revealed the formation of the ZnO nanorods with hexagonal wurtzite structure. The CO 2 sensing properties of the resistive-type sensor based on ZnO nanorods assisted by polyvinyl alcohol (ZFS) investigated as a function of gas concentration and relative humidity (RH) at room temperature. The response and response time of the ZFS reduced with increasing RH from 30 to 90% at various gas levels. The sensor showed the highest response of 120.3% at 0.3 vol% CO 2 and 30% RH, while it exhibited a proper response of 81% at 90% RH and 0.037 vol% CO 2. Moreover, the lowest response time (recovery time) of 51.3 s (34 s) at 0.3 (0.037) vol% CO 2 and 90% RH was obtained. We found that our handmade sensor has superior response features at dynamic conditions, a good CO 2 selectivity, and long-term stability. Finally, the probable CO 2 sensing mechanism of the ZFS was discussed in detail.
Innovative metal oxide nanosystems for gas sensing: From design to application
Nuovo Cimento della Societa Italiana di Fisica B, 2008
The present contribution highlights some of the key results recently obtained by our research group in the development of innovative metal oxide nanosystems for gas sensors. In particular, the attention is devoted to the tailored synthesis of columnar CeO2 nanostructures, ZnO nanoplatelets and ZnO-TiO2 nanocomposites. The systems were properly designed and synthesized by means of Chemical Vapor Deposition (CVD) routes, with special focus on the control of their morphogenesis by tailoring the growth conditions. Compositional, microstructural, morphological and electrical characterization data of the obtained innovative nanomaterials are presented and their peculiarities are highlighted, with special emphasis to the detection of target gases for environmental and food control applications.
Journal of Materials Science: Materials in Electronics, 2019
Zinc oxide (ZnO) as a highly sensitive metal oxide semiconductor is exerting a growing significant influence on the detection of hazardous gases such as carbon monoxide gas (CO). However, elevated operating temperature and humidity have been exhibited the bottleneck of CO detection at ambient conditions. Therefore, in the present work, one-dimensional ZnO nanoneedles (ZON) were synthesized by a simple hydrothermal method, and their resistance-type gas sensor was made and applied for the CO sensing features investigation at environmental conditions. The ZON characterization has exhibited a hexagonal wurtzite phase of the pure crystallized ZnO with porous architecture. The CO sensing properties of the ZON sensor (ZS) were studied in various gas concentrations and relative humidity (RH), to examine these main factors at room temperature. Our handmade sensor was exhibited an appropriate response, long-term stability for more than 4 months, and it had good selectivity to CO concentration than that other gases. Moreover, the ZS showed a linear relationship between the response and not only the gas concentrations at various RHs but also the RH toward different gas concentrations, which is very important for the calibration and practical use. Finally, the CO sensing mechanism of the ZS at ambient conditions was discussed as well.
2023
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.
Fabrication of Tin Oxide Nanoparticles for CO 2 Gas Sensing Layer
IETE Journal of Research , 2018
Tin-oxide-based metal oxide nanoparticles synthesis method and characterization results are reported. These tin-oxide nanoparticles have been synthesized using the ultrasonic probe method. The morphology and surface characteristics of synthesized nanoparticles have been analyzed through electron microscopy and X-ray diffraction technique. The sensitivity of carbon dioxide gas detection has been tested using a sensing layer prototype.
Metal Oxide Nanostructures and Their Gas Sensing Properties: A Review
Metal oxide gas sensors are predominant solid-state gas detecting devices for domestic, commercial and industrial applications, which have many advantages such as low cost, easy production, and compact size. However, the performance of such sensors is significantly influenced by the morphology and structure of sensing materials, resulting in a great obstacle for gas sensors based on bulk materials or dense films to achieve highly-sensitive properties. Lots of metal oxide nanostructures have been developed to improve the gas sensing properties such as sensitivity, selectivity, response speed, and so on. Here, we provide a brief overview of metal oxide nanostructures and their gas sensing properties from the aspects of particle size, morphology and doping. When the particle size of metal oxide is close to or less than double thickness of the space-charge layer, the sensitivity of the sensor will increase remarkably, which would be called "small size effect", yet small size of metal oxide nanoparticles will be compactly sintered together during the film coating process which is disadvantage for gas diffusion in them. In view of those reasons, nanostructures with many kinds of shapes such as porous nanotubes, porous nanospheres and so on have been investigated, that not only possessed large surface area and relatively mass reactive sites, but also formed relatively loose film
Excellent CO gas sensor based on Ga-doped ZnO nanoparticles
Journal of Materials Science: Materials in Electronics, 2015
Sol-gel technique was utilized to prepare pure and Ga-doped ZnO nanopowders. To investigate the morphological and microstructural properties, transmission electron microscopy analysis and X-ray powder diffraction have been used. From microstructure analysis we showed that pure and Ga-doped ZnO nanoparticles were polycrystalline, and exhibited hexagonal wurtzite structure. Chemoresistive devices consisting of a thick layer of synthesized nanoparticles on interdigitated alumina substrates have been fabricated and their electrical and sensing characteristics were investigated. The sensor performances of the samples for carbon monoxide (CO) were reported. The results indicated that doped sensor exhibited higher response and quick response/recovery dynamics compared to a ZnO-based sensor. These interesting sensing properties were discussed on the basis of the characterization data were reported.
Characterization of ZnO Nanorods and SnO2-CuO Thin Film for CO Gas Sensing
Transactions on Electrical and Electronic Materials, 2012
In this study, ZnO nanorods and SnO 2-CuO heterogeneous oxide were grown on membrane-type gas sensor platforms and the sensing characteristics for carbon monoxide (CO) were studied. Diaphragm-type gas sensor platforms with built-in Pt micro-heaters were made using a conventional bulk micromachining method. ZnO nanorods were grown from ZnO seed layers using the hydrothermal method, and the average diameter and length of the nanorods were adjusted by changing the concentration of the precursor. Thereafter, SnO 2-CuO heterogeneous oxide thin films were grown from evaporated Sn and Cu thin films. The average diameters of the ZnO nanorods obtained by changing the concentration of the precursor were between 30 and 200 nm and the ZnO nanorods showed a sensitivity value of 21% at a working temperature of 350℃ and a carbon monoxide concentration of 100 ppm. The SnO 2-CuO heterogeneous oxide thin films showed a sensitivity value of 18% at a working temperature of 200℃ and a carbon monoxide concentration of 100 ppm.
Synthesis of metal and metal oxide nanostructures and their application for gas sensing
A method has been developed to synthesize metal and metal oxide nanostructures in high yields on the surface of SiO 2 /Si substrate. In this method, starting materials in a covered alumina crucible are thermally evaporated under a high vacuum or a low pressure of ambient air. Spherical gold nanoparticles with a size of 15 nm and nanowires with a diameter of 70 nm were synthesized. SnO 2 rough microwires, smooth nanowires, and nanoknives were synthesized by using Sn granules, SnO powder, and SnO 2 powder as source materials, respectively. The microwires showed a quadrangular cross section and a length of several microns, while the nanowires showed a circular cross section and approximately the same length. The effects of source temperature and deposition time on nanostructure growth were studied. X-ray diffraction patterns suggested that the as-synthesized products consisted of crystalline nanostructure. Nanocomposite gas sensors on the base of noble metal and metal oxide were fabricated. These SnO 2 nanowire gas sensors showed a reversible response to dilute NO 2 gas at operating temperatures ranging between room temperature and 300 • C even at high concentrations. The results demonstrated that gold doping improved the sensor response.