Special Issue "Nanostructured Gas Sensors"

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Nanoelectronics, Nanosensors and Devices".

Deadline for manuscript submissions: 25 September 2021.

Special Issue Editor

Dr. Dario Zappa
E-Mail Website
Guest Editor
Sensor Lab, Department of Information Engineering (DII), University of Brescia, Via Valotti 9, 25133 Brescia, Italy
Interests: metal oxides; nanowires; chemical sensors; heterostructures; artificial olfaction; material characterization; material synthesis
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

In recent years, the need of effective gas detection systems has grown in various fields of analytical chemistry, such as gas leak detection in domestic appliances; environmental monitoring; and the food, pharmaceutical, and automotive industries. Nanotechnology presents the possibility of leveraging fundamental mechanisms at the nanoscale in order to control all the basic properties (structural, chemical, electronic, and optical) of a microsystem. This enables the development of innovative chemical sensors with enhanced sensing capabilities, improved selectivity and sensitivity, and higher reliability. Therefore, researchers working in material science have focused their attention and efforts on developing new materials for their eventual exploitation in real-world applications.

Among the first materials investigated, metal oxide (MOX) exhibits good chemical and thermal stability and encouraging performance. At the nanoscale, these materials have very high specific surface area, which enhances their sensitivity to chemical molecules. Conductometric devices based on MOX semiconductors are well known and particularly suited for the chemical detection in the vapour phase, with detection limits down to the ppb level. However, they often lack selectivity and require high operating temperatures, limiting their application. Surface functionalization, doping, or the combination of materials to form composites have been studied to overcame these limitations.

Recently, ultrathin two-dimensional (2D) nanomaterials have been receiving increasing interest after the discovering of exfoliated graphene from graphite 2004. These 2D nanomaterials, like graphene, transition metal dichalcogenides (TMDs), and others, are crystalline materials consisting of a single layer of atoms. They have some unique properties that strongly differ from zero- (0D, like nanoparticles) or one- (1D, nanowires and nanotubes) dimensional materials. These properties can be exploited in devices for applications such as photovoltaics; electrodes; and, more specifically, sensors.

This Special Issue mainly focuses on presenting the new developments of material science, specifically with regard to the promising approaches that will contribute to further advances in the gas-sensing field. Recent advances in science and technology will be addressed, including fabrication techniques and advanced processing technologies; growth mechanisms of novel high-performance materials with improved properties; and new transduction mechanisms that differ from the traditional conductometric, transistor-based, and optical ones.

We invite you to submit a manuscript for this Special Issue. Full papers, communications, and reviews are all welcome.

Dr. Dario Zappa
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Chemical sensors
  • Carbon- and dichalcogenides-based materials
  • Metal oxides
  • 2D compounds
  • Organic and/or inorganic materials
  • Synthesis and characterization of nanomaterials
  • Modifications of the materials, doping, and heterostructures
  • Graphene
  • Gas–nanomaterial interactions
  • Quasi 1D materials: nanowires, nanotubes, and nanorords
  • Transduction mechanisms
  • Gas sensors
  • Humidity sensors
  • Gas detection

Published Papers (6 papers)

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Research

Open AccessFeature PaperArticle
Gas Sensing with Solar Cells: The Case of NH3 Detection through Nanocarbon/Silicon Hybrid Heterojunctions
Nanomaterials 2020, 10(11), 2303; https://doi.org/10.3390/nano10112303 - 21 Nov 2020
Cited by 2 | Viewed by 733
Abstract
Photovoltaic (PV) cells based on single-walled carbon nanotube (SWCNT)/silicon (Si) and multiwalled carbon nanotube (MWCNT)/Si junctions were tested under exposure to NH3 in the 0–21 ppm concentration range. The PV cell parameters remarkably changed upon NH3 exposure, suggesting that these junctions, [...] Read more.
Photovoltaic (PV) cells based on single-walled carbon nanotube (SWCNT)/silicon (Si) and multiwalled carbon nanotube (MWCNT)/Si junctions were tested under exposure to NH3 in the 0–21 ppm concentration range. The PV cell parameters remarkably changed upon NH3 exposure, suggesting that these junctions, while being operated as PV cells, can react to changes in the environment, thereby acting as NH3 gas sensors. Indeed, by choosing the open-circuit voltage, VOC, parameter as read-out, it was found that these cells behaved as gas sensors, operating at room temperature with a response higher than chemiresistors developed on the same layers. The sensitivity was further increased when the whole current–voltage (I–V) curve was collected and the maximum power values were tracked upon NH3 exposure. Full article
(This article belongs to the Special Issue Nanostructured Gas Sensors)
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Open AccessArticle
Metal Oxide Nanolayer-Decorated Epitaxial Graphene: A Gas Sensor Study
Nanomaterials 2020, 10(11), 2168; https://doi.org/10.3390/nano10112168 - 30 Oct 2020
Cited by 1 | Viewed by 625
Abstract
In this manuscript, we explore the sensor properties of epitaxially grown graphene on silicon carbide decorated with nanolayers of CuO, Fe3O4, V2O5, or ZrO2. The sensor devices were investigated in regard to their [...] Read more.
In this manuscript, we explore the sensor properties of epitaxially grown graphene on silicon carbide decorated with nanolayers of CuO, Fe3O4, V2O5, or ZrO2. The sensor devices were investigated in regard to their response towards NH3 as a typical reducing gas and CO, C6H6, CH2O, and NO2 as gases of interest for air quality monitoring. Moreover, the impact of operating temperature, relative humidity, and additional UV irradiation as changes in the sensing environment have been explored towards their impact on sensing properties. Finally, a cross-laboratory study is presented, supporting stable sensor responses, and the final data is merged into a simplified sensor array. This study shows that sensors can be tailored not only by using different materials but also by applying different working conditions, according to the requirements of certain applications. Lastly, a combination of several different sensors into a sensor array leads to a well-performing sensor system that, with further development, could be suitable for several applications where there is no solution on the market today. Full article
(This article belongs to the Special Issue Nanostructured Gas Sensors)
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Open AccessArticle
Highly Catalytic Electrochemical Oxidation of Carbon Monoxide on Iridium Nanotubes: Amperometric Sensing of Carbon Monoxide
Nanomaterials 2020, 10(6), 1140; https://doi.org/10.3390/nano10061140 - 10 Jun 2020
Viewed by 788
Abstract
The nanotubular structures of IrO2 and Ir metal were successfully synthesized without any template. First, IrO2 nanotubes were prepared by electrospinning and post-calcination, where a fine control of synthetic conditions (e.g., precursor concentration and solvent composition in electrospinning solution, temperature increasing [...] Read more.
The nanotubular structures of IrO2 and Ir metal were successfully synthesized without any template. First, IrO2 nanotubes were prepared by electrospinning and post-calcination, where a fine control of synthetic conditions (e.g., precursor concentration and solvent composition in electrospinning solution, temperature increasing rate for calcination) was required. Then, a further thermal treatment of IrO2 nanotubes under hydrogen gas atmosphere produced Ir metal nanotubes. The electroactivity of the resultant Ir metal nanotubes was investigated toward carbon monoxide (CO) oxidation using linear sweep voltammetry (LSV) and amperometry. The anodic current response of Ir metal nanotubes was linearly proportional to CO concentration change, with a high sensitivity and a short response time. The amperometric sensitivity of Ir metal nanotubes for CO sensing was greater than a nanofibrous counterpart (i.e., Ir metal nanofibers) and commercial Pt (20 wt% Pt loading on carbon). Density functional theory calculations support stronger CO adsorption on Ir(111) than Pt(111). This study demonstrates that metallic Ir in a nanotubular structure is a good electrode material for the amperometric sensing of CO. Full article
(This article belongs to the Special Issue Nanostructured Gas Sensors)
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Open AccessArticle
Seed-Assisted Growth of TiO2 Nanowires by Thermal Oxidation for Chemical Gas Sensing
Nanomaterials 2020, 10(5), 935; https://doi.org/10.3390/nano10050935 - 13 May 2020
Cited by 5 | Viewed by 839
Abstract
Herein, we report the catalyst assisted growth of TiO2 one-dimensional (1D) nanowires (NWs) on alumina substrates by the thermal oxidation technique. RF magnetron sputtering was used to deposit a thin Ti metallic layer on the alumina substrate, followed by an Au catalytic [...] Read more.
Herein, we report the catalyst assisted growth of TiO2 one-dimensional (1D) nanowires (NWs) on alumina substrates by the thermal oxidation technique. RF magnetron sputtering was used to deposit a thin Ti metallic layer on the alumina substrate, followed by an Au catalytic layer on the Ti metallic one. Thermal oxidation was carried out in an oxygen deficient environment. The optimal thermal growth temperature was 700 °C, in a mixture environment composed by Ar and O2. As a comparison, Ti films were also oxidized without the presence of the Au catalyst. However, without the Au catalyst, no growth of nanowires was observed. Furthermore, the effect of the oxidation temperature and the film thickness were also investigated. SEM, TEM, and EDX studies demonstrated the presence of Au nanoparticles on top of the NWs, indicating that the Au catalyst drove the growth process. Raman spectroscopy revealed the Rutile crystalline phase of TiO2 NWs. Gas testing measurements were carried out in the presence of a relative humidity of 40%, showing a reversible response to ethanol and H2 at various concentrations. Thanks to the moderate temperature and the easiness of the process, the presented synthesis technique is suitable to grow TiO2 NWs for many different applications. Full article
(This article belongs to the Special Issue Nanostructured Gas Sensors)
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Open AccessArticle
UV-Enhanced Humidity Sensing of Chitosan–SnO2 Hybrid Nanowires
Nanomaterials 2020, 10(2), 329; https://doi.org/10.3390/nano10020329 - 14 Feb 2020
Cited by 2 | Viewed by 801
Abstract
The surface of SnO2 nanowires was functionalized by chitosan for the development of room-temperature conductometric humidity sensors. SnO2 nanowires were synthesized by the seed-mediated physical-vapor-deposition (PVD) method. Chitosan layers were deposited on top of the SnO2 nanowires by spin coating. [...] Read more.
The surface of SnO2 nanowires was functionalized by chitosan for the development of room-temperature conductometric humidity sensors. SnO2 nanowires were synthesized by the seed-mediated physical-vapor-deposition (PVD) method. Chitosan layers were deposited on top of the SnO2 nanowires by spin coating. Surface morphology, crystal structure, and optical properties of the synthesized hybrid nanostructure were investigated by scanning electron microscope, grazing incidence X-ray diffraction, and UV–Vis absorption measurements. During electrical conductivity measurements, the hybrid nanostructure showed unusual behavior towards various relative humidity (RH) concentrations (25%, 50%, 75%), under UV-light irradiation, and in dark conditions. The highest sensor responses were recorded towards an RH level of 75%, resulting in 1.1 in the dark and 2.5 in a UV-irradiated chamber. A novel conduction mechanism of hybrid nanowires is discussed in detail by comparing the sensing performances of chitosan film, SnO2 nanowires, and [email protected]2 hybrid nanostructures. Full article
(This article belongs to the Special Issue Nanostructured Gas Sensors)
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Open AccessArticle
Organic-Inorganic Hybrid Materials for Room Temperature Light-Activated Sub-ppm NO Detection
Nanomaterials 2020, 10(1), 70; https://doi.org/10.3390/nano10010070 - 28 Dec 2019
Cited by 3 | Viewed by 1182
Abstract
Nitric oxide (NO) is one of the main environmental pollutants and one of the biomarkers noninvasive diagnosis of respiratory diseases. Organic-inorganic hybrids based on heterocyclic Ru (II) complex and nanocrystalline semiconductor oxides SnO2 and In2O3 were studied as sensitive [...] Read more.
Nitric oxide (NO) is one of the main environmental pollutants and one of the biomarkers noninvasive diagnosis of respiratory diseases. Organic-inorganic hybrids based on heterocyclic Ru (II) complex and nanocrystalline semiconductor oxides SnO2 and In2O3 were studied as sensitive materials for NO detection at room temperature under periodic blue light (λmax = 470 nm) illumination. The semiconductor matrixes were obtained by chemical precipitation with subsequent thermal annealing and characterized by XRD, Raman spectroscopy, and single-point BET methods. The heterocyclic Ru (II) complex was synthesized for the first time and characterized by 1H NMR, 13C NMR, MALDI-TOF mass spectrometry and elemental analysis. The HOMO and LUMO energies of the Ru (II) complex are calculated from cyclic voltammetry data. The thermal stability of hybrids was investigated by thermogravimetric analysis (TGA)-MS analysis. The optical properties of Ru (II) complex, nanocrystalline oxides and hybrids were studied by UV-Vis spectroscopy in transmission and diffuse reflectance modes. DRIFT spectroscopy was performed to investigate the interaction between NO and the surface of the synthesized materials. Sensor measurements demonstrate that hybrid materials are able to detect NO at room temperature in the concentration range of 0.25–4.0 ppm with the detection limit of 69–88 ppb. Full article
(This article belongs to the Special Issue Nanostructured Gas Sensors)
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