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Highly sensitive and selective room-temperature NO2 gas-sensing characteristics of SnOX-based p-type thin-film transistor
摘要： The high-performance p-type metal-oxide-semiconductor (MOS)-based gas sensor is an important subject of research in the field of gas-sensing technology. In this work, we demonstrated a p-type MOS-based thin-film transistor (TFT) nitrogen dioxide (NO2) gas sensor that used tin oxide (SnOX) for both the channel and sensing layers. The crystalline status, surface morphology, and atomic-bonding configuration of the thin-film were examined using X-ray diffraction, field emission-scanning electron microscopy, and X-ray photoelectron spectroscopy. The results indicated that the deposited thin-film was mainly composed of polycrystalline SnO with a tetragonal structure. The fabricated p-type SnOX TFT showed a maximum response value of 19.4-10 ppm NO2 at room temperature (RT, 25 °C) when operated in the subthreshold region, which was significantly higher than that of 2.8–10 ppm NO2 obtained from a p-type SnOX thin-film chemiresistor at RT. In addition, the SnOX TFT gas sensor showed significantly higher sensitivity to NO2 gas than to other target gases such as NH3, H2S, CO2, and CO at RT. To the best of our knowledge, this is the first study to a p-type MOS-based field-effect transistor-type gas sensor. Our experimental results demonstrate that the p-type SnOX TFT is a promising gas sensor that can operate at RT with high sensitivity and selectivity to NO2 gas.
关键词： SnO,Thin-film transistor,NO2 gas sensing,SnOX,P-type metal oxide semiconductor
更新于2025-11-21 11:01:37
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Sub-ppm level NO2 sensing properties of polyethyleneimine-mediated WO3 nanoparticles synthesized by a one-pot hydrothermal method
摘要： A novel sensing material of polyethyleneimine-mediated WO3 nanoparticles was prepared by a simple and efficient one-pot hydrothermal method. The structure and morphology characteristics of the as-prepared WO3 nanoparticles were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The results showed that the as-prepared WO3 nanomaterials were composed of highly dispersible WO3 nanoparticles, and these nanoparticles with the particle size in the range of 10e50 nm showed a monoclinic structure. NO2 sensing measurements demonstrated that WO3 nanoparticles-based gas sensor exhibited superior response, outstanding selectivity, excellent reversibility, and good long-term stability. The sensor response increased as NO2 concentration increased. The highest response value of 251.7 was achieved to 5 ppm NO2 at the optimal operating temperature of 100 (cid:1)C. Especially, the sensor response could reach 3.2e50 ppb NO2. It also exhibited fast response and recovery times with a high sensor response even in a high-humidity environment. The excellent gas sensing properties of WO3 nanoparticles could be ascribed to their high effective surface areas as well as numerous oxygen vacancies, which foresee the great potential application for fast and effective detection of sub-ppm level NO2 under different humidity environments.
关键词： Nanoparticles,NO2,Gas sensing performance,WO3,Hydrothermal
更新于2025-09-23 15:23:52
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Controlled synthesis of ultrathin MoS <sub/>2</sub> nanoflowers for highly enhanced NO <sub/>2</sub> sensing at room temperature
摘要： Fabrication of a high-performance room-temperature (RT) gas sensor is important for the future integration of sensors into smart, portable and Internet-of-Things (IoT)-based devices. Herein, we developed a NO2 gas sensor based on ultrathin MoS2 nanoflowers with high sensitivity at RT. The MoS2 flower-like nanostructures were synthesised via a simple hydrothermal method with different growth times of 24, 36, 48, and 60 h. The synthesised MoS2 nanoflowers were subsequently characterised by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy. The petal-like nanosheets in pure MoS2 agglomerated to form a flower-like structure with Raman vibrational modes at 378 and 403 cm?1 and crystallisation in the hexagonal phase. The specific surface areas of the MoS2 grown at different times were measured by using the Brunauer–Emmett–Teller method. The largest specific surface area of 56.57 m2 g?1 was obtained for the MoS2 nanoflowers grown for 48 h. This sample also possessed the smallest activation energy of 0.08 eV. The gas-sensing characteristics of sensors based on the synthesised MoS2 nanostructures were investigated using oxidising and reducing gases, such as NO2, SO2, H2, CH4, CO and NH3, at different concentrations and at working temperatures ranging from RT to 150 °C. The sensor based on the MoS2 nanoflowers grown for 48 h showed a high gas response of 67.4% and high selectivity to 10 ppm NO2 at RT. This finding can be ascribed to the synergistic effects of largest specific surface area, smallest crystallite size and lowest activation energy of the MoS2-48 h sample among the samples. The sensors also exhibited a relative humidity-independent sensing characteristic at RT and a low detection limit of 84 ppb, thereby allowing their practical application to portable IoT-based devices.
关键词： gas sensing,room temperature,hydrothermal synthesis,MoS2 nanoflowers,NO2 gas sensor
更新于2025-09-23 15:19:57
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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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NO<sub>2</sub> gas sensing performance enhancement based on reduced graphene oxide decorated V<sub>2</sub>O<sub>5</sub> thin film
摘要： Here, we demonstrate the improved NO2 gas sensing properties based on reduced graphene oxide (rGO) decorated V2O5 thin film. Excluding the DC sputtered grown V2O5 thin film, rGO was spread over V2O5 thin film by drop cast method. The formation of several p-n heterojunctions is greatly affected by the current-voltage relation of rGO decorated V2O5 thin film due to p-type and n-type nature of rGO and V2O5, respectively. Initially with rGO decoration on V2O5 thin film, current decreases in comparison to V2O5 thin film, whereas depositing rGO film on glass substrate, current increases drastically. Among all sensors, only rGO decorated V2O5 sensor revealed maximum NO2 gas sensing response for 100 ppm at 150°C, and helped achieve approximately 61% times more response than the V2O5 sensor. An elaborated mechanism for an extremely high sensing response is attributed to the formation and modulation of p-n heterojunction at the interface of rGO and V2O5. In addition, the presence of active sites like oxygenous functional groups on rGO surface also enhances the sensing response. On that account, the sensor based on rGO decorated V2O5 thin film is highly suitable for the purpose of NO2 gas sensing. This enables timely detection of the gas, further prevent the ecosystem from its harmful effects.
关键词： NO2 gas,relative response,DC sputtering,p-n heterojunction,rGO decorated V2O5 thin film
更新于2025-09-19 17:15:36
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Multifunctional inorganic nanomaterial aerogel assembled into fSWNT hydrogel platform for ultraselective NO2 sensing
摘要： Facile fabrication of multifunctional porous inorganic aerogels remains an outstanding challenge despite the considerable demand for extensive applications. Here, we present the production of a multifunctional porous inorganic nanomaterial aerogel by controllable surface chemistry of a functionalized SWNT (fSWNT) hydrogel platform for the first time. The versatile functional inorganic nanoparticles can be incorporated uniformly on the porous 3D fSWNT hydrogel platform through a facile dip coating method at ambient conditions. The morphology of the multifunctional inorganic aerogel is manipulated by designing the fSWNT hydrogel platform for different requirements of applications. In particular, Pt-SnO2@fSWNT aerogels exhibit high porosity and uniformly distributed ultrafine Pt and SnO2 on the fSWNT platform with controllable particle size (1.5–3.5 nm), which result in significantly high surface area (393 m2 g-1). The ultrafine Pt-SnO2@fSWNT aerogels exhibit highly sensitive (14.77% at 5 ppm) and selective NO2 sensing performance even at room temperature due to the increased active surface area and controllable porous structure of the ultrafine aerogel, which can provide fast transport and penetration of a target gas into the sensing layers. The newly designed multifunctional inorganic aerogel with ultrahigh surface area and high open porosity is a prospective materials platform of high performance gas sensors, which could be also broadly expanded to widespread applications including catalysis and energy storages.
关键词： fSWNT hydrogel platform,room temperature sensor,ultraselective NO2 gas sensing,Pt-SnO2@fSWNT aerogel,Multifunctional ultrafine inorganic aerogel
更新于2025-09-19 17:13:59
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2D Plasmonic Tungsten Oxide Enabled Ultrasensitive Fiber Optics Gas Sensor
摘要： Functional materials coated on optical fibers have demonstrated great potential for optical gas sensing applications. However, their sensitivity is typically limited to the sub-parts per million (sub-ppm) range. Here, for the first time a 2D near-infrared plasmonic tungsten oxide (WOx) enabled ultrasensitive fiber optics gas sensor on a side-polished D-shape single mode optical fiber is presented. The plasmon resonance wavelength range of 2D WOx is matched with a conventional telecommunications wavelength of 1550 nm for driving the optical fiber, therefore inducing a strong light–matter interaction. Upon the surface adsorption of gas molecules, free electrons in the 2D WOx body are redistributed changing the plasmon resonance properties and hence the transmission through the optical fiber. The sensor is selectively responsive to NO2 at concentrations down to 44 parts per billion (ppb) with a limit of detection of 8 ppb at a relatively low elevated temperature. Such an excellent sensing performance is significantly improved over the previously reported fiber optics NO2 sensors, which suggests the integration of 2D plasmonic degenerated semiconductors as a viable approach to develop high-performance fiber optics gas sensors.
关键词： fiber optics,2D materials,NO2 gas sensors,plasmonic materials
更新于2025-09-11 14:15:04
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Enhanced NO2 gas-sensing properties of Au-Ag bimetal decorated MWCNTs/WO3 composite sensor under UV-LED irradiation
摘要： Novel NO2 gas sensors that were made of Ag, Au and Au-Ag bimetal particles modified composite of multi-walled carbon nanotubes/tungsten oxide (Ag/MWCNTs/WO3, Au/MWCNTs/WO3 and Au-Ag/MWCNTs/WO3) were fabricated for sensing ppb-level NO2 gas under ultraviolet light emitting diode (UV-LED) irradiation. The effects of Ag, Au and Au-Ag bimetal decoration and under UV-LED irradiation on the response of the Ag/MWCNTs/WO3, Au/MWCNTs/WO3 and Au-Ag/MWCNTs/WO3 sensors for sensing NO2 gas were studied. The gas-sensing properties in the detection of a low concentration of NO2 gas of the Au-Ag/MWCNTs/WO3 composite were superior to bare MWCNTs/WO3, Au/MWCNTs/WO3 and Ag/MWCNTs/WO3 under UV-LED irradiation. The Au-Ag/MWCNTs/WO3 composite sensor showed responses of 28–262 % at NO2 concentrations ranging from 100 to 500 ppb under UV-LED irradiation. These responses were 2–5 times higher than that of the bare MWCNTs/WO3 composite sensor at the same NO2 concentration range. The substantial improvement in the response of the bare MWCNTs/WO3 composite to NO2 gas by its decoration with Au-Ag bimetal particles may be attributed to the enhanced catalytically active sites and photocatalytic activity. A reasonable mechanism for enhancing sensitivity was proposed.
关键词： UV irradiation,NO2 gas sensor,Photocatalytic activity,Au-Ag bimetal
更新于2025-09-11 14:15:04
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MoS2 hybrid heterostructure thin film decorated with CdTe quantum dots for room temperature NO2 gas sensor
摘要： MoS2 hybrid heterostructure thin film decorated with CdTe quantum dots for room temperature NO2 gas sensor
关键词： Hybrid heterostructure,Sputtering,NO2 gas sensor,CdTe/MoS2 thin film
更新于2025-09-11 14:15:04
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Core-Shell Electrospun Polycrystalline ZnO Nanofibres for Ultra-Sensitive NO2 Gas Sensing
摘要： This paper discusses the growth of polycrystalline, self-supporting ZnO nanofibres which can detect nitrogen dioxide (NO2) gas down to 1 part per billion (ppb), one of the smallest detection limits reported for NO2 using ZnO. A new and innovative method has been developed for growing polycrystalline ZnO nanofibres. These nanofibres have been created using core-shell electrospinning of inorganic metal precursor zinc neodecanoate, where growth occurs at the core of the nanofibres. This process produces contamination-free, self-supporting, polycrystalline ZnO nanofibres of the average diameter and grain size 50 nm and 8 nm respectively, which are ideal for gas sensing applications. This process opens up an exciting opportunity for creating nanofibres from a variety of metal oxides, facilitating many new applications especially in the areas of sensors and wearable technologies.
关键词： NO2 gas sensing,polycrystalline fibres,ZnO nanofibres,Electrospinning
更新于2025-09-09 09:28:46