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Formation, Charge Transfer, Structural and Morphological Characteristics of ZnO Fractal-Percolation Nanosystems
摘要： Structural and morphological characteristics of ZnO nanosystems in the form of three-dimensional network-like systems have been investigated. Current–voltage (I–V) characteristics and charge transfer parameters of ZnO fractal-percolation nanosystems have been studied both in air and in vacuum at different temperatures and voltage sweep rates. The charge transfer characteristics show the presence of RaCiCai chains in the nanosystems. The RC chains are formed because the Debye screening length has the same order of magnitude as the local values of ZnO nanowires radii. Gas-sensing tests based on I–V characteristics investigation have shown a possibility of distinguishing between reducing gases such as CH4 or C2H5OH.
关键词： current–voltage characteristics,gas sensor,ZnO nanowires,charge transfer,reducing gas
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - Finite Element Modelling and Computational Analysis of Mechanical Properties of Carbon Composite-Based Love Wave Sensor
摘要： Structured materials are of interest to emphasize the sensitivity of gas or bio-sensors. This work focuses on carbon-polymer composite (PEDOT:PSS-MWCNT) and additional multiwalled carbon nanotubes (MWCNT), deposited by inkjet printing on Love acoustic wave devices. This combination is studied, both with simulation based on finite element modelling and computational analysis of a reduced model, and experimental measurements. This allows for an estimation of the Young modulus of each material: 70 GPa and 150 GPa for the PEDOT:PSS-MWCNT bilayer composite material (? 450nm) and for the MWCNT bilayer on carbon composite (?140nm), respectively. The value is lower than that obtained in the literature, which has been attributed to the material porosity. An enhanced waveguiding effect is observed, which is interesting for further detection applications.
关键词： MWCNT,PEDOT:PSS,Gas sensor,FEM,SAW,Bio sensor
更新于2025-09-19 17:15:36
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Morphological Evolution Induced through Heterojunction of W-decorated NiO Nanoigloos: Synergistic Effect on High-performance Gas Sensors
摘要： Morphological evolution accompanying a surface roughening and the preferred orientation is an effective way to realize a high-performance gas sensor because of its significant potential as a chemical catalyst by chemical potentials and atomic energy states. In this work, we investigated the heterojunction of both-sided W-decorated NiO nanoigloos fabricated through RF sputtering and a soft-template method. Interestingly, the morphological evolution characterized by a pyramidal rough surface and the preferred orientation of the (111) plane was observed upon decorating the bare NiO nanoigloos with W. The underlying mechanism of the morphological evolution was precisely demonstrated based on a van der Drift competitive growth model originating from the oxygen transport and chemical strain in a lattice. The gas sensing properties of W-decorated NiO show an excellent NO2 response and selectivity when compared to other gases. In addition, high response stability was evaluated under interference gas and humidity condition. The synergistic effects on the sensing performance were interpreted based on the morphological evolution of W-decorated NiO nanoigloos.
关键词： Gas sensor,Nanostructure,Morphological evolution,Heterojunction,NO2
更新于2025-09-19 17:15:36
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Ultra-Sensitive H<sub>2</sub>S Gas Sensor Based on WO<sub>3</sub> Nanocubes with Low Operating Temperature
摘要： WO3 nanostructure with nanocube morphology was synthesized through acidification of Na2WO4·2H2O, which were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, the result of the present work implied that the sensor fabricated by nanocube WO3 could detect the level of 330 ppb H2S, which is much lower than the threshold limit value of 10 ppm. Compared with other results, the nanocube WO3 sensor shows higher sensitivity, excellent selectivity and faster response/recovery to H2S. Especially, the best operating temperature of this nanocube WO3 for H2S detection is 100 oC.
关键词： H2S,Gas sensor,Nanomaterials,WO3
更新于2025-09-19 17:15:36
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Characterization and NO2 gas sensing performance of CdO:In2O3 polycrystalline thin films prepared by spray pyrolysis technique
摘要： Polycrystalline CdO:In2O3 thin films for gas sensor applications were prepared on glass and silicon substrates by using one-step spray pyrolysis technique from the aqueous solution of CdCl2 and InCl3 at a substrate temperature of 300 °C. The structure, surface morphology, and the optoelectronic properties of prepared films were characterized respectively by means of X-ray diffraction (XRD), atomic force microscope and UV–visible spectroscopy. Based on the XRD results, the polycrystalline nature of CdO films has been confirmed, and In2O3 films were found to exhibit a preferred orientation along (222) diffracted plane. The grain size varies between 9.0 and 28.4 nm. The results of Hall effect measurement of CdO:In2O3 thin films confirms that all films were an n-type semiconductor. The electrical properties of prepared thin films and their sensitivity to nitrogen dioxide (NO2) gas are also studied. The influence of the operating temperature and In2O3 concentration on the NO2 response were investigated. It is found that all films are sensitive to NO2 gas, and the ideal operating temperature for the film contented 20 vol% of In2O3 was found to be 200 °C at a gas concentration of 25 ppm. The sensing mechanism of the CdO:In2O3 thin film is discussed and attributed to electron transfer between the sensing element and NO2 molecules.
关键词： NO2 gas sensor,Sensitivity,Optoelectronic properties,Structural,Morphology,Metal-oxide semiconductors
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - Defect Control in MoO<inf>3</inf> Nanostructures as Ethanol Sensor
摘要： Transformation of MoO3 nanobelts into MoO3 nanofibers with high surface defect has been achieved by the application of pulsed temperature during hydrothermal growth. MoO3 nanobelts and nanofibers are characterized by field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and surface area analysis by nitrogen adsorption-desorption technique. Results clearly revealed that high crystalline, lower thickness, high surface area, and high surface defects are present in the MoO3 nanofibers as compare to MoO3 nanobelts. Furthermore, ethanol sensing properties of these MoO3 nanobelts and MoO3 nanofibers were examined, where MoO3 nanofibers show superior ethanol sensing properties due to the above mention advantages in MoO3 nanofibers.
关键词： defect,ethanol,gas sensor,MoO3 nanofibers
更新于2025-09-19 17:15:36
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Complex-surfactant-assisted hydrothermal synthesis of one-dimensional ZnO nanorods for high-performance ethanol gas sensor
摘要： One-dimensional (1D) ZnO nanorods (ZNRs) were synthesized by a facile and effective hydrothermal method using the mixture of sodium dodecyl sulfate (SDS) and polyethylene glycol 400 (PEG400) with a molar ratio of 1:1 as the complex surfactant. The microstructure and morphology were characterized using of X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results demonstrated that the ZNRs are of a single crystal hexagonal wurtzite structure, having a larger length-to-diameter ratio with more regular surface morphology compared with the ZnO products obtained in the presence of only SDS or PEG400. A possible growth mechanism was proposed based the mediation reaction of the complex surfactant. Gas sensing measurements indicated that the ZNRs assisted by the complex surfactant demonstrated excellent ethanol sensing properties at an optimal operating temperature of 300 °C, which could be ascribed to their large length-to-diameter ratio, one-dimensional structure, and numerous surface defects of oxygen vacancies.
关键词： Zinc oxide,Gas sensor,Ethanol,Nanorods,Complex surfactant
更新于2025-09-19 17:15:36
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All-Fiber CO2 Sensor Using Hollow Core PCF Operating in the 2 μm Region
摘要： A realistic implementation of an all-fiber CO2 sensor, using 74 cm of hollow core photonic crystal fiber (HC-PCF) as the cavity for light/gas interaction, has been implemented. It is based on CO2 absorbance in the 2 μm region. The working range is from 2% to 100% CO2 concentration at 1 atm total pressure and the response time obtained was 10 min. Depending on the concentration level, the sensor operates at one of three different wavelengths (2003.5 nm, 1997.0 nm and 1954.5 nm) to maintain a high sensitivity across all the working range.
关键词： gas,sensor,tunable laser,carbon dioxide monitoring,fiber bragg grating,photonic crystal fiber
更新于2025-09-19 17:15:36
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Improved Sensing Capability of Integrated Semiconducting Metal Oxide Gas Sensor Devices
摘要： Semiconducting metal oxide (SMO) gas sensors were designed, fabricated, and characterized in terms of their sensing capability and the thermo-mechanical behavior of the micro-hotplate. The sensors demonstrate high sensitivity at low concentrations of volatile organic compounds (VOCs) at a low power consumption of 10.5 mW. In addition, the sensors realize fast response and recovery times of 20 s and 2.3 min, respectively. To further improve the baseline stability and sensing response characteristics at low power consumption, a novel sensor is conceived of and proposed. Tantalum aluminum (TaAl) is used as a microheater, whereas Pt-doped SnO2 is used as a thin film sensing layer. Both layers were deposited on top of a porous silicon nitride membrane. In this paper, two designs are characterized by simulations and experimental measurements, and the results are comparatively reported. Simultaneously, the impact of a heat pulsing mode and rubber smartphone cases on the sensing performance of the gas sensor are highlighted.
关键词： electro-thermal-mechanical simulation,semiconducting metal oxide,ultra-low power,gas sensor,smartphone,microheater
更新于2025-09-19 17:15:36
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Ultrathin nanowire based on icosahedral W@Au12 and application as NO gas sensor
摘要： In this study, we used first-principles calculations to investigate the structural and electronic properties of an ultrathin nanowire formed by assembling icosahedral W@Au12 clusters and its application as a NO gas sensor. An ultrathin nanowire with a diameter of about 5.52 ? was produced via the coalescence of icosahedral W@Au12 clusters. The W@Au12-based nanowire exhibited semiconducting properties with a direct band gap. Frequency analysis and molecular dynamics simulations indicated that the nanowire was particularly stable at T = 300 K. The nanowire chemisorbed a NO molecule with moderate adsorption energy, and the N atom in NO bonding with the Au atom was the most stable bond. Analysis of the Boltzmann distribution and transition state demonstrated that the most stable configuration was particularly likely to form. The electronic properties of the W@Au12-based nanowire were changed dramatically by NO adsorption, with a transition from semiconducting to conducting behavior after NO adsorption. However, the adsorption of CO2, CH4, O2, H2, N2, or H2O molecules had little effect on the conductance of the nanowire. Our results indicated that the W@Au12-based nanowire sensor was highly sensitive and selective. The recovery time for the nanowire-based NO sensor was about 12 s at T = 300 K. Therefore, due to its moderate adsorption energy, significant change in the electric conductivity, and very rapid recovery time, we conclude that the W@Au12-based nanowire is a promising gas sensor with high performance at NO detection.
关键词： Icosahedral W@Au12,Assembly,Density functional theory calculation,NO gas sensor,Nanowire
更新于2025-09-19 17:15:36