共查询到20条相似文献,搜索用时 31 毫秒
1.
The design of core–shell heteronanostructures is powerful tool to control both the gas selectivity and the sensitivity due to their hybrid properties. In this work, the SnO 2–ZnO core–shell nanowires (NWs) were fabricated via two-step process comprising the thermal evaporation of the single crystalline SnO 2 NWs core and the spray-coating of the grainy polycrystalline ZnO shell for enhanced ethanol sensing performance. The as-obtained products were investigated by X-ray diffraction, scanning electron microscopy, and photoluminescence. The ethanol gas-sensing properties of pristine SnO 2 and ZnO–SnO 2 core–shell NW sensors were studied and compared. The gas response to 500 ppm ethanol of the core–shell NW sensor increased to 33.84, which was 12.5-fold higher than that of the pristine SnO 2 NW sensor. The selectivity of the core–shell NW sensor also improved. The response to 100 ppm ethanol was about 14.1, whereas the response to 100 ppm liquefied petroleum gas, NH 3, H 2, and CO was smaller, and ranged from 2.5 to 5.3. This indicates that the core–shell heterostructures have great potential for use as gas sensing materials. 相似文献
2.
SnO 2 nanofibers were synthesized by electrospinning method, and then, treated by oxygen plasma. The morphology and structure of treated SnO 2 nanofibers were analyzed using XRD, SEM, and TEM. The composition and specific surface of treated SnO 2 nanofibers were analyzed by EDX, XPS, and BET. The treated SnO 2 nanofibers showed more pores on the surface of the nanofibers. The size of treated SnO 2 nanoparticles in the nanofibers are ~20 nm. The porosity of the treated SnO 2 nanofibers was higher than that of the untreated. The gas sensing properties of the SnO 2 nanofibers to formaldehyde were measured before and after materials treated by oxygen plasma. The treated SnO 2 nanofibers exhibit low operating temperature and large response values. Cross-responses of the treated SnO 2 nanofibers sensor were tested. The sensing mechanism of the SnO 2 nanofibers gas sensor treated by oxygen plasma was briefly analyzed. 相似文献
3.
Ultrafine-structure La 0.65Sr 0.35MnO 3 (LSM) powders synthesized by self-propagating combustion method have been used to fabricate sensing electrodes (SEs) for NO 2 mixed-potential sensors based on yttria-stabilized zirconia (YSZ). This type of sensor was found to provide better NO 2 sensitivity at 500 °C than sensors with LSM powders synthesized by traditional solid-state methods. The response values of the sensor have good linear relationship (sensitivity 36.6 mV/decade and linear fit 0.99) with the logarithm of NO 2 concentration varying from 30 to 500 ppm. The influence of sintering temperature (1000, 1100, 1200, and 1300 °C) on sensor response was also examined and was found to have a significant effect on the morphology of LSM-SEs. Moreover, in the presence of NO, CO 2, CO, and NO 2, the sensor exhibited good NO 2 selectivity. 相似文献
4.
Titanium oxide nanoparticles were coated on multiwall carbon nanotubes (MWCNTs) using an atmospheric pressure chemical vapor
deposition (CVD) to achieve highly compact nanoparticles of about 5 nm on CNT structure. The CNTs with a diameter of about
50 nm were grown by plasma enhanced CVD. Gas sensitivity of the fabricated structure was investigated and compared with TiO 2/CNT composite-based gas sensors. The effect of the structural interaction between the nanoparticles and the CNT wall on sensing
mechanism of the as-prepared gas sensors was investigated. Ultrasensitive gas sensors were obtained by TiO 2/CNT nanostructures with strong interaction between the MWCNT and the TiO 2 nanoparticles. The measurements show high chemical activity and exceptional electrical response of the as-prepared structure
being exposed to gases. Scanning and transmission electron microscopy and X-ray diffraction analysis were used to obtain structural
information. 相似文献
5.
The article presents a combined theoretical and experimental study attempting to show how Pd nanoparticles (NPs) loading onto SnO 2 substrate improves the acetone gas sensing performance. Pristine nanostructured SnO 2 and Pd nanoparticles (Pd NPs) loaded SnO 2 substrates have been prepared, characterized, and their acetone sensing performances have been measured. Experimental measurements have shown that Pd NP loading onto SnO 2 suppresses the interfering effects of ethanol, water vapors, etc., and enhances the acetone sensor response, reversibility, response/recovery speeds, and signal-to-noise ratio. Various parameters like the adsorption energy, HOMO–LUMO energy gap, charge distribution, polarizability change, electrophilicity index, global hardness, etc., of several model systems, have been computed by using DFT. The computed parameters have been correlated with the conductivity, local reactivity, sensor response and selectivity, response/recovery times, etc., of the systems to understand the molecular-level effects of the Pd NP loading onto the SnO 2 on the gas sensing process. 相似文献
6.
Based on the experimental results, obtained by studying both structural and gas-sensing properties of the SnO 2 and In 2O 3 films deposited by the spray pyrolysis method, we analyzed the influence of crystallite size on the parameters of the SnO 2- and In 2O 3-based thin film solid-state gas sensors. For comparison, the behavior of ceramic-type gas sensors was considered as well. In particular, we examined the correlation between the grain size and parameters of conductometric-type gas sensors such as the magnitude of sensor signal, the rate of sensor response, thermal stability, and the sensitivity of sensor signal to air humidity. Findings confirmed that that grain size is one of the most important parameters of metal oxides, controlling almost all operating characteristics of the solid state gas sensors fabricated using both the ceramic and thin film technologies. However, it was shown that there is no single universal requirement for the grain size, because changes in grain size could either improve, or worsen of operating characteristics of gas sensors. Therefore, the choice of optimal grain size should be based on the detailed consideration of all possible consequences of their influence on the parameters of sensors designed. 相似文献
7.
This paper reports on a simple and inexpensive ultrasonic spray pyrolysis method to synthesize agglomerate-free nanosized SnO 2 particles with a size smaller than 10 nm. Scanning electron microscopy, transmission electron microscopy and high resolution X-ray diffraction studies were used to characterize the morphology, crystallinity, and structure of the SnO 2 particles. Under the optimized experimental conditions, the prepared SnO 2 sensor shows the high response ( S = 491) towards 100 ppm ethanol gas at 300 °C, linearity in the range of 100–500 ppm, quick response time (2 s), recovery time (60 s) and selectivity against other gases. The response of the sensor was monitored in a 250–450 °C temperature range. The seven fold enhancement in gas response and selective detection of C 2H 5OH in the presence of other gases such as CH 3OH and CH 3CHOHCH 3 are the significant points in this investigation. These results demonstrate that pure nanocrystalline SnO 2 thin film can be used as the sensing material for fabricating high performance ethanol sensors. 相似文献
8.
The CdSnO 3 semiconducting oxide that can be used as a gas-sensitive material for detecting ethanol gas is reported in this paper. CdSnO 3 nanoparticles were prepared by a chemical co-precipitation synthesis method, in which the preparation conditions were carefully
controlled. The n-type gas-sensing semiconductors were obtained from the as-synthesized powders calcined at 600°C for 1 h.
The phase and microstructure of the obtained nanoparticles were characterized by X-ray diffraction (XRD), transmission electron
microscopy (TEM), and Brunauer–Emmett–Teller (BET) method with a gas adsorption analyzer. CdSnO 3 has a small particle size range of 30–50 nm and a high surface area of 9.12 m 2/g, and a uniformity global shape. The gas sensitivity and operating temperature, and selectivity of CdSnO 3-based sensors were measured in detail. The gas sensors fabricated by CdSnO 3 nanoparticles had good sensitivity and selectivity to vapor of C 2H 5OH when working temperature at 267°C, the value of gas sensitivity at 100 ppm of C 2H 5OH gas can reach 11.2 times. Furthermore, gas-sensing mechanism was studied by using chromatographic analysis. 相似文献
9.
Effects of functionalization materials on the selectivity of SnO 2 nanorod gas sensors were examined by comparing the responses of SnO 2 one-dimensional nanostructures functionalized with CuO and Pd to ethanol and H 2S gases. The response of pristine SnO 2 nanorods to 500 ppm ethanol was similar to 100 ppm H 2S. CuO-functionalized SnO 2 nanorods showed a slightly stronger response to 100 ppm H 2S than to 500 ppm ethanol. In contrast, Pd-functionalized SnO 2 nanorods showed a considerably stronger response to 500 ppm ethanol than to 100 ppm H 2S. In other words, the H 2S selectivity of SnO 2 nanorods over ethanol is enhanced by functionalization with CuO, whereas the ethanol selectivity of SnO 2 nanorods over H 2S is enhanced by functionalization with Pd. This result shows that the selectivity of SnO 2 nanorods depends strongly on the functionalization material. The ethanol and H 2S gas sensing mechanisms of CuO- and Pd-functionalized SnO 2 nanorods are also discussed. 相似文献
10.
Sensors highly sensitive to CO gas that are based on Ag-doped SnO 2 nanoparticles are shown to be a feasibility. The structure and composition of the respective films versus the SnO 2 nanoparticle size are studied. The electrical parameters of the sensor materials are measured. It is shown that exposure of the nanostructured films to carbon monoxide considerably decreases their resistance and shifts the frequency of a maximum in the impedance curves toward lower values. Specific features of the IR reflection spectra in the range of excitation of carbon and oxygen atom vibrations are revealed. 相似文献
11.
Metal oxide semiconductor gas sensors operating under UV irradiation have been validated for detection of variety of chemicals in wide ranges of concentrations at room temperature. This article reviews recent advances in UV-activated metal oxide gas sensors in general and outlines the operating principles and sensing performance of UV-LED based sensors in particular. The sensing properties of several metal oxide semiconductors such as ZnO, TiO 2, SnO 2, In 2O 3, and metal oxide composites under UV-LED irradiation are individually presented and their advantages and shortcomings toward various gases are compared. Moreover, it is demonstrated that for the UV-LED based gas sensors, the performance can be improved by optimizing the sensor platform design and UV source parameters such as wavelength and power intensity. Further, it is illustrated that the gas sensing selectivity can be tuned by modifying the semiconductor layer structure or adjusting appropriate wavelength to an optimal value. 相似文献
12.
Tin dioxide nanoparticles and zinc oxide nanorods were synthesized chemically and thick film gas sensors on alumina substrates
were fabricated of these materials. Morphology and crystallite size of synthesized powders were investigated by TEM. The fabricated
sensors were irradiated with 100 MeV O 7+ ions at fluences of 1×10 11, 1×10 12 and 1×10 13 ions/cm 2. The X-ray diffraction analysis of the samples before and after ion bombardment was performed for structural characterization.
The sensing response to ethanol before and after irradiation was carried out for each fabricated sensor. Investigation revealed
that irradiated SnO 2 based sensor’s response and response time increased significantly. Results show that ZnO based sensor exhibit strong resistance
to damage caused by ion irradiation which might be due to defects annihilation. 相似文献
13.
A kind of novel ZnSnO 3/SnO 2 hollow urchin nanostructure was synthesized by a facile, eco-friendly two-step liquid-phase process. The structure, morphology, and composition of samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption–desorption techniques. The results revealed that many tiny needle-like SnO 2 nanowires with the average diameter of 5 nm uniformly grew on the surface of the ZnSnO 3 hollow microspheres and the ZnSnO 3/SnO 2 hollow urchin nanostructures with different SnO 2 content also were successfully prepared. In order to comprehend the evolution process of the ZnSnO 3/SnO 2 hollow urchin nanostructures, the possible growth mechanism of samples was illustrated via several experiments in different reaction conditions. Moreover, the gas-sensing performance of as-prepared samples was investigated. The results showed that ZnSnO 3/SnO 2 hollow urchin nanostructures with high response to various concentration levels of acetone enhanced selectivity, satisfying repeatability, and good long-term stability for acetone detection. Specially, the 10 wt% ZnSnO 3/SnO 2 hollow urchin nanostructure exhibited the best gas sensitivity (17.03 for 50 ppm acetone) may be a reliable biomarker for the diabetes patients, which could be ascribed to its large specific surface area, complete pore permeability, and increase of chemisorbed oxygen due to the doping of SnO 2. 相似文献
14.
The present investigation has been carried out to optimize the pH level of lanthanum (La)-doped tin dioxide (SnO2) nanoparticles towards the potential application in gas sensor. The La-doped SnO2 nanoparticles were synthesized by sol-gel method in different pH values varying from acidic to base nature. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), ultraviolet (UV), photoluminescence (PL), and scanning electron microscopy (SEM) techniques. The XRD, UV, and PL analyses show the pH influences on the crystallite size of La-doped SnO2 nanoparticles. The SEM images show the formation of porous structure at pH 11. Also, the electrical conductivity of 1 mol% La-doped SnO2 at pH 3 and pH 11 were measured by impedance analyzer. In addition, we have fabricated and demonstrated device performance of synthesized La-doped SnO2 nanoparticles for gas-sensing application. Real-time current response and long-time response to the gas sensing were also studied for the fabricated device. 相似文献
15.
MoO 3 nanoparticles were prepared by thermally oxidizing the MoO 2 nano-crystallites synthesized by solvothermal reaction, and their gas sensing properties were investigated. Ethanol and water
mixed solvents were used in the solvothermal synthesis, and it was observed that the phase, size, and morphology of the products
were strongly dependent on the composition of solvents. Well-crystallized and spherical MoO 2 nano-crystallites (~20 nm) were obtained in the mixed solvent (water:ethanol = 40:10 in vol), and subsequent heat treatment
at 450 °C produced the well-separated, slightly elongated MoO 3 nano-particles of ~100 nm. The nano-particle MoO 3 gas sensor responded to both oxidizing and reducing gases, but it exhibited the extremely high gas response toward H 2S with a short response time (<10 s). In particular, the magnitude of gas response of nano-particle MoO 3 gas sensor was about 10 times higher than that of micron-sized commercial MoO 3 powder sensor at 20 ppm H 2S. 相似文献
16.
This work studied the possibility of using a sensor based on plasma-sprayed zinc oxide (ZnO) sensitive layer for NO 2 detection. The atmospheric plasma spray process was employed to deposit ZnO gas sensing layer and the obtained coating structure was characterized by scanning electron microscopy and X-ray diffraction analysis. The influences of gas concentration, working temperature, water vapor in testing air on NO 2 sensing performance of the ZnO sensors were studied. ZnO sensors showed a good sensor response and selectivity to NO 2 at an optimal working temperature. 相似文献
17.
Chemo-sensor technology demands to design a single, preconcentrator based sensing system having higher sensitivity, sufficient selectivity and efficient removal of metal ions with simple operating and recognition methodology. Here we effectively deliberated Ce doped SnO 2 nanoparticles based sensing system which can be exploited for the recognition and extraction of Co(II) ions in a single step by strong interaction between Ce doped SnO 2 nanoparticles and Co(II). The sensing ability of Ce doped SnO 2 nanoparticles were deliberated for a selective removal of cobalt using inductively coupled plasma-optical emission spectrometry. The sensing ability of Ce doped SnO 2 is studied for various metal ions, such as Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Ni(II) and Zn(II) but the designed sensor was most selective toward Co(II) which was 5000 time more sensitive to Co(II) rather than different interfering metal ions. In addition, the desorption study for regeneration of Ce doped SnO 2 nanoparticles was carried out. This novel approach provides a new route for simultaneous detection and removal of Co(II) in a single step and can be a time and cost alternative tool for environmental safety. 相似文献
18.
A sonochemical method is developed to fabricate SnO 2 nanotubular materials from biological substances (here, it is cotton). The cotton fibers in SnCl 2 solution were first treated with ultrasonic waves in air, followed by calcinations to give nanotubular materials that faithfully
retain the initial cotton morphology. The microstructure and morphology of the obtained SnO 2 nanotubules were characterized by the combination of field-emission scanning electron microscope (FE-SEM), transmission electron
microscopy (TEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and N 2 adsorption/desorption measurements. The thermal behavior and crystalline properties were examined in the temperature range
of 450–700 °C. The nanocrystals composing of SnO 2 nanotubules were estimated about 8.5, 13.2, and 14.2 nm corresponding to calcination temperatures of 450, 550, and 700 °C,
respectively. The sensor performance of biomorphic SnO 2 nanotubules calcined at 700 °C was investigated in the atmosphere of ethanol, formaldehyde, carbinol, carbon monoxide, hydrogen,
ammonia, and acetone, respectively, which exhibited a good selectivity for acetone at a working temperature of 350 °C. The
sensitivity to 20 ppm acetone, S, was 6.4 at 350 °C with rapid response and recovery (around 10–9 s). These behaviors were well explained in relation to the
morphology of the nanotubules thus produced. 相似文献
19.
This paper presents the transfer of SnO 2 by laser induced forward transfer (LIFT) for gas sensor applications. Different donor substrates of SnO 2 with and without triazene polymer (TP) as a dynamic release layer were prepared. Transferring these films under different conditions were evaluated by optical microscopy and functionality. Transfers of sputtered SnO 2 films do not lead to satisfactory results and transfers of SnO 2 nanoparticles are difficult. Transfers of SnO 2 nanoparticles can only be achieved when applying a second laser pulse to the already transferred material, which improves the adhesion resulting in a complete pixel. A new approach of decomposing the transfer material during LIFT transfer was developed. Donor films based on UV absorbing metal complex precursors namely, SnCl 2(acac) 2 were prepared and transferred using the LIFT technique. Transfer conditions were optimized for the different systems, which were deposited onto sensor-like microstructures. The conductivity of the transferred material at temperatures of about 400 °C are in a range usable for SnO 2 gas sensors. First sensing tests were carried out and the transferred material proved to change conductivity when exposed to ethanol, acetone, and methane. 相似文献
20.
A novel sensitive electrochemical sensor has been developed by modification of glassy carbon electrode (GCE) with graphene (GRP), chitosan (CHIT), and bismuth oxide (Bi 2O 3) nanoparticles. The morphological characteristics of nanocomposite (GRP-CHIT-Bi 2O 3 or GCB) were studied by scanning electron microscope and atomic force microscopy. The electrochemical behavior of epinephrine at nanocomposite modified GCE (GCB/GCE) was investigated in pH 7.4 phosphate buffer solution using cyclic voltammetry and square wave voltammetry. GCB/GCE showed an enhancement in the current response as compared to bare GCE. Electrochemical impedance spectra showed a reduction of charge transfer resistance and higher electrocatalytic behavior of the sensor. The electrooxidation process of epinephrine at the modified sensor was found to be diffusion controlled. GCB/GCE showed a linear response to epinephrine in the range 100 to 500 nM. The limit of detection and limit of quantification were found to be 3.56 and 11.85 nM, respectively, which is lower than many other sensors reported for epinephrine in literature. The modified sensor showed high sensitivity (1.3 nA/nM) and selectivity for epinephrine. The method was employed for quantification of epinephrine in pharmaceutical formulation and human blood serum samples. 相似文献
|