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A high-performance room temperature methanol gas sensor based on alpha-iron oxide/polyaniline/PbS quantum dots nanofilm
摘要： A high-performance room temperature methanol gas sensor based on alpha-iron oxide/polyaniline/lead sulfide quantum dots (α-Fe2O3/PANI/PbS QDs) nanofilm was demonstrated in this paper, among which the α-Fe2O3 was an urchin-shaped hollow microsphere. The sensing film was fabricated on an epoxy substrate with interdigital electrodes via successive ionic layer adsorption and reaction technique. The prepared α-Fe2O3/PANI/PbS QDs nanocomposite was examined by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, scanning election microscopy and Fourier transform infrared spectrum. The methanol sensing performances of the α-Fe2O3/PANI/PbS QDs film sensor were investigated against methanol from 10 to 100 ppm at room temperature. The experimental results indicated that the methanol sensor in this work had an excellent response, outstanding selectivity and good repeatability at room temperature. The underlying sensing mechanism of the α-Fe2O3/PANI/PbS QDs film toward methanol was ascribed to a series of interactions and changes on the surface of thin films, which make their resistance change greatly. Larger surface area and much more active adsorption sites also played an important role.
关键词： Methanol gas sensor,Room temperature,Successive ionic layer adsorption and reaction,Hydrothermal method,α-Fe2O3/PANI/PbS QDs
更新于2025-11-14 17:15:25
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Ethanol sensing properties and reduced sensor resistance using porous Nb2O5-TiO2 n-n junction nanofibers
摘要： One-dimensional (1D) and porous Nb2O5-TiO2 n-n junction nanofibers with different Nb molar ratios have been synthesized by a simple electrospinning approach. A decrease in the average grain size and consequently an increase in the specific surface area were observed due to the introduction of Nb2O5 into TiO2 nanofibers. In comparison with pure TiO2 nanofibers, the Nb2O5-TiO2 nanofibers exhibited improved ethanol sensing response and a reduction in electrical resistance. The optimum operation temperature was reduced from 300 °C for pure TiO2 to 250 °C for Nb2O5-TiO2. The best sensing property was found for Nb2O5-TiO2 with 6 mol% Nb2O5, showing the highest response of 21.64–500 ppm ethanol at 250 °C, which was 2.79 times as high as that of pure TiO2 nanofibers at 300 °C. The reduction of Nb2O5-TiO2 based sensor resistance was attributed to the substitution of Ti4+ by Nb5+ ions and the formation of n-n junctions between Nb2O5 nanoparticles and TiO2 nanoparticles. The enhancement sensing mechanism of Nb2O5-TiO2 nanofibers was mainly ascribed to the enhanced resistance modulation owing to the substitution of Ti4+ by Nb5+ ions, formation of n-n junctions, and high surface area as well as small grain size of Nb2O5-TiO2 nanofibers.
关键词： Gas sensor,n-n junctions,Electrospinning,Nb2O5,TiO2
更新于2025-11-14 17:15:25
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Improvement of Sensing Performance of Impedancemetric C2H2 Sensor Using SmFeO3 Thin-Films Prepared by a Polymer Precursor Method
摘要： A sensitive an impedancemetric acetylene (C2H2) gas sensor device could be fabricated by using perovskite-type SmFeO3 thin-film as a sensor material. The uniform SmFeO3 thin-films were prepared by spin-coating and focusing on the effects of polymer precursor solutions. The prepared precursors and thin-films were characterized by means of thermal analysis, Fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction analysis, scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that particle growth and increase in homogeneity of the prepared thin-film could be accelerated by the addition of acetyl acetone (AcAc) as a coordination agent in the polymer precursor solution. Moreover, the highly crystallized thin-film-based sensor showed good response properties and stabilities to a low C2H2 concentration between 0.5 and 2.0 ppm.
关键词： polymer precursor,acetyl acetone,thin-film,gas sensor,acetylene,perovskite-type oxide,AC impedance
更新于2025-11-14 15:15:56
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Selective H2S-sensing performance of Si nanowires through the formation of ZnO shells with Au functionalization
摘要： A novel gas sensor fabricated from ZnO-shelled Si nanowires (SiNWs) is presented. After coating a thin layer of Au on the surfaces of Si NWs, ZnO layers were formed on the surfaces of p-SiNWs by thermal evaporation of Zn powders and a subsequent oxidation process. Microscopic analysis confirmed the successful formation of ZnO-Si core-shell NWs with Au nanoparticles present on the shell surface. The gas sensing performance of the gas sensor fabricated using the p-Si/n-ZnO core-shell NWs was evaluated for various gases. The sensor exhibited outstanding response and selectivity to H2S gas. The gas sensing mechanism was evaluated in detail and attributed to various factors, including the formation of ZnO/Si and Au/ZnO heterojunctions and the chemical attraction between ZnO and Au. The results demonstrate a new sensing material for H2S detection in various fields that can be easily incorporated into Si-based devices.
关键词： Gas Sensor,Si Nanowires,ZnO,Sensing Mechanism,Shell,Au
更新于2025-11-14 15:15:56
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Electrical Properties of Porous Silicon for N2 Gas Sensor
摘要： The application of porous silicon (PSi) for gas sensing devices has gained a considerable attention in the last decade. This work considers the electrical features of PSi layers prepared by electrochemical etching. We find that in order to get a better understanding of the absorption properties of PSi surface, it is necessary to know how the PSi morphology depends on the etching parameters. The physical structure of PSi, i.e., porosity, and pore size distribution can be controlled by changing the Hydrofluoric Acid concentration, current density, anodizing length and etching time in anodizing procedure. We describe our test system for gas sensors and investigate on the electrical behavior of PSi layers (p-type) in N2 gas for various fabrication conditions. The results show that the current density increases significantly as N2 gas is adsorbed. The measurements of the I-V characteristics were carried out at atmospheric pressure, room temperature, and with N2 gas as well.
关键词： Current-voltage curve,N2 gas,Porous silicon,Gas sensor
更新于2025-09-23 15:23:52
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Resistive room temperature LPG sensor based on a graphene/CdO nanocomposite
摘要： The authors decribe an ultra-sensitive, room temperature, flexible transparent LPG sensor based on the use of a CdO/graphene nanocomposite. The graphene prevents the accumulation of CdO, enhances the surface area, and acts as a gas sensing material. FESEM images show a uniform decoration of CdO nanoparticles on graphene. The CdO/graphene composite was deposited as a film on interdigitated electrodes (IDEs) which then were used for chemiresistive sensing of liquid petroleum gas (LPG) by using a four probe technique. A Resistivity decreases significantly upon exposure to a LPG. The electrical resistance measurement at a constant bias voltage of 0.5 V. The sensor of type CdO/graphene (1 wt.%) exhibits a sensitivity of 600 ppm of LPG at 27 °C. It is a highly selective, stable and sensitive to low concentration of LPG even at room temperature.
关键词： Gas sensor,CdO,Liquefied petroleum gas,Graphene,Flexible
更新于2025-09-23 15:23:52
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Manganese-doped zinc oxide hollow balls for chemiresistive sensing of acetone vapors
摘要： Both pure and Mn(II)-doped ZnO hollow structures were synthesized by a solvothermal reaction, and their phase structures, morphologies and elemental composition were characterized. SEM and TEM observations show the pure ZnO and the Mn(II)-doped ZnO balls to possess similar hollow structure with a particle size of about 1.5 μm. Their sensing properties were investigated, and the composite containing 1 atom% of Mn(II) (1% Mn-ZnO) is found be display the highest selectivity for acetone. The detection limit is 100 ppm acetone at 234 °C which is 4.6 times lower than that of the pure ZnO. In addition, the response time is shorter.
关键词： Hollow balls,Gas sensor,ZnO,Acetone vapors,Mn-doped ZnO
更新于2025-09-23 15:23:52
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High acetic acid sensing performance of Mg-doped ZnO/rGO nanocomposites
摘要： Mg-doped ZnO/reduced graphene oxide (rGO) nanocomposites were synthesized using a facile and cost-effective sol-gel procedure to detect acetic acid vapor. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) diffuse reflectance spectroscopy, and photoluminescence (PL) analysis were utilized to characterize morphologies, compositions of the nanocomposites, and optical properties of the synthesized nanostructures. The gas sensing measurements of spin-coated Mg-doped ZnO/rGO thin films were carried out for a temperature range of 150–350 oC at various acetic acid vapour concentrations. It was found that the Mg-doped sample with 20 wt. %/v of GO solution concentration exhibited the response/recovery time of 60 s/35 s with the best response of ~200% for 100 ppm of acetic acid at 250 oC.
关键词： Mg-doped ZnO/rGO,Gas sensor,Acetic acid,Nanoparticles
更新于2025-09-23 15:23:52
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Organic Transistor Based on Cyclopentadithiophene-Benzothiadiazole Donor-Acceptor Copolymer for the Detection and Discrimination between Multiple Structural Isomers
摘要： Distinguishing structural isomers is a critical and challenging task for biotechnology, chemical industry, and environmental monitoring. Approaches currently available are limited in terms of selectivity and simplicity. In this paper, a highly sensitive organic field-effect transistor (OFET) using the cyclopentadithiophene-benzothiadiazole (CDT-BTZ) copolymers as a semiconductor is presented for easy and selective detection of different families of structural isomers, as well as between different isomers within each family. High accuracy discrimination is achieved over a range of concentrations using only a single sensing parameter derived from the OFET characteristic transfer curve. As a reference, other homopolymer- and donor–acceptor copolymer-based OFET sensors are examined but do not have an equivalent sensing performance to that of the CDT-BTZ-based OFETs. Investigating the link between isomer absorption and swelling, supramolecular order and energy levels of the active layer reveals a unique effect of each isomer on the energy bands of the semiconducting polymer.
关键词： isomers,donor–acceptor copolymers,gas sensor,organic field-effect transistor,xylenes
更新于2025-09-23 15:23:52
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Highly selective and sensitive xylene gas sensor fabricated from NiO/NiCr2O4 p-p nanoparticles
摘要： Xylene is a harmful and hazardous volatile organic compound (VOC) indoors, thus selective and sensitive detection for subppm-level xylene is crucial, however a remained challenge. In this work, p-NiO/p-NiCr2O4 nanocomposites were successfully synthesized through a simple hydrothermal route and used as sensing materials. In the comparative gas sensing test, the sensor fabricated from NiO/NiCr2O4 (Cr/Ni=25 at%) nanocomposite exhibited the highest response (66.2-100 ppm) to xylene, which was 37.2 times higher than that of the pure NiO sensor. Moreover, the NiO/NiCr2O4 nanocomposite gas sensor showed not only superior xylene selectivity with low cross-responses to interfering gases such as ethanol (Sxylene/Sethanol =11.8) and acetone (Sxylene/Sacetone =10.2) but also ppb-level detection limit (1.2-50 ppb xylene) at 225 °C. The synergistic catalytic effect between NiO and NiCr2O4, optimized structural parameters and marked resistive variation due to the formation of nanoscale p-p heterojunctions were regarded as the main reasons for the ultrasensitive and selective xylene detection.
关键词： selectivity,xylene detection,heterojunction,gas sensor,NiO/NiCr2O4
更新于2025-09-23 15:23:52