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1.
The sensor properties of nanostructured films of SnO 2, In 2O 3, and their combinations for detecting CO in air in the temperature range of 330–520°C were investigated. It was found that
SnO 2 films show the least sensitivity to CO. Sensitivity grows as the concentration of In 2O 3 in SnO 2 increases, and it reaches its maximum value in pure In 2O 3. At the same time, the maximum of sensitivity to CO in air shifts towards low temperatures. Sensor response time was found
to be about 1 s for the studied SnO 2 and In 2O 3 films, and about 0.5 s for the composite film. The mechanism of sensor sensitivity for the studied metal oxide films in detecting
CO in air is discussed. 相似文献
2.
The sensor properties of In 2O 3 · SnO 2 polycrystalline films having different compositions were studied in the detection of 2% hydrogen in air over the temperature
range 330–530°C. Films containing 19% In 2O 3 were most sensitive to hydrogen. The temperature dependence of the sensitivity of sensors passed a maximum, the position
of which depended on the composition of the film. The temperature at which sensor sensitivity was maximum decreased as the
content of indium oxide increased. This temperature was 485°C for the SnO 2 film and 425°C for the In 2O 3 film. The response and relaxation times of sensors also decreased as the amount of In 2O 3 in the composite metal oxide film increased. Possible mechanisms of the sensor sensitivity of the films are discussed. 相似文献
3.
The sensor properties of nanostructured In 2O 3-CeO 2 composite films with different compositions in hydrogen and carbon monoxide detection in air in the temperature range 280–500°C were studied. The temperature curves of the sensor effect S have a shape typical for metal oxide sensors with maxima S max at definite temperatures Tmax. The maxima characterize the sensor properties of the films and increased considerably when small amounts of CeO 2 were added to In 2O 3. The highest sensitivity was found in composite films with 3–10 wt % CeO 2. When the composite was further enriched with ceric oxide, the sensitivity decreased; at 40 wt % CeO 2 it was considerably lower than that of pure In 2O 3. The introduction of CeO 2 in In 2O 3 also caused a shift of Tmax toward lower temperatures. The mechanism of the sensitivity of the In 2O 3-CeO 2 composite was considered; it includes the promotion of sensor reactions by small CeO 2 nanoclusters lying on the surface of In 2O 3 crystals and an electron transfer from In 2O 3 to CeO 2. 相似文献
4.
Catalytic and sensing properties of several metal oxides in the reaction of CO oxidation and in the sensor detection of CO in air have been studied and compared to each other. Indium oxide has been found to be the most sensitive and possessing a relatively low catalytic activity in the oxidation of CO. Possible reasons for the high activity of the indium oxide sensor matrix are discussed. The promoting effect of Au and Pd doping of In 2O 3in the detection of CO in air has been studied, and a mechanism explaining the enhanced sensor response of Au-doped In 2O 3has been proposed. A change in humidity has no significant effect on the sensor response of Au-doped In 2O 3in the detection of CO in air. 相似文献
5.
A number of sensing systems based on indium oxide doped with various metal oxides (In 2O 3 · WO 3, In 2O 3 · ZnO, In 2O 3 · RuO 2, In 2O 3 · Gd 2O 3, and In 2O 3 · Sm 2O 3) in amounts of no more than 3–5 mol % and also Au · In 2O 3 films were studied as sensors for detecting NO 2 in air. The working temperature of sensors was 250°C (except for In 2O 3 · RuO 2, for which T = 150–190°C). In 2O 3 · WO 3-based sensors reach a high sensitivity especially at a concentration of NO 2 in air higher than 10 ppm (the relative sensor conductivity changes by 2.5 orders of magnitude). However, a shortcoming of this system is an increased response time (7–9 min) as compared to the other studied systems, for which the response time does not exceed 15–20 s. In 2O 3 · Gd 2O 3 and In 2O 3 · Sm 2O 3 films exhibit the best sensing properties in sensitivity, selectivity, and stability. Various NO 2 species adsorbed on the surface of dispersed indium oxide were detected by Fourier-transform IR spectroscopy. The mechanism of changing the conductivity of In 2O 3 · Gd 2O 3 films upon detecting NO 2 in air is discussed. 相似文献
6.
Comparative studies of electophysical gas-sensitive properties of semiconductor metal oxides (NiO, WO 3, and In 2O 3) in detecting trace concentrations of chlorine in air at 250–300°C were performed. WO 3 and In 2O 3 film sensors were found to have the best sensitivity, selectivity, and stability. However, WO 3 films are characterized by a longer relaxation time (3 min) compared to In 2O 3 films, for which it is no longer than 30 s. The kinetic and steady-state relative conductivity values of In 2O 3 films as functions of the chlorine concentration in air fall on the same curve in the range 0.01–0.7 ppm. This suggests that the concentration of chlorine in air can be determined from the initial rates of the variation of the relative conductivity of films, which significantly decreases the time of analysis (from 40 to 5 s at a sensor working temperature of 300°C). Changes in air humidity in the range from 40 to 80% have no effect on the initial rates of the variation of the relative conductivity of In 2O 3 films under kinetic conditions. The mechanism of the variation of In 2O 3 film conductivity in detecting chlorine in air was discussed. 相似文献
7.
The dependence of a sensor’s response to hydrogen on the temperature and hydrogen pressure in an indium oxide nanostructured film is measured. A theory of sensor’s response to reducing gases in nanostructured semiconducting oxides with high concentrations of electrons in the conduction band is developed (using the example of In2O3). It is shown that the capture of conduction electrons by adsorbed oxygen redistributes the electrons in nanoparticles and reduces the surface electron density and the conductivity of a system; the conductivity is proportional to the electron density in nanoparticle contacts, i.e., to the surface electron density. It is found that atomic oxygen ions react with reducing gases (H2, CO) during adsorption of the latter: electrons are released and enter the volumes of nanoparticles; the conductivity of the system grows, creating the sensory effect. Using a model developed earlier to describe the distribution of conduction electrons in a semiconductor nanoparticle, a kinetic scheme corresponding to the above scenario is built and corresponding equations are solved. As a result, a theoretical dependence of a sensor’s sensitivity to temperature is found that describes the experimental data well. 相似文献
8.
A possibility was demonstrated of producing the chemical sensors based on Au-In 2O 3 obtained using a sol-gel technology. The sensors exhibit high sensitivity and selectivity toward CO. The differences in gas-sensitivity
properties of In 2O 3 sensor with respect to CO and CH 4 at different ways of doping with Au(III) was examined. The effect of the gold nanoparticles size and the state of the indium
oxide surface on the characteristics of Au-In 2O 3 and Au/In 2O 3 sensors at the detection of CO and CH 4 was examined. 相似文献
9.
Nanostructure single ZnO, SnO 2, In 2O 3 and composite ZnO/SnO 2, ZnO/In 2O 3 and ZnO/SnO 2/In 2O 3 films were prepared using sol?Cgel method. The obtained composite films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV?CVis spectroscopy. The photocatalytic activities of composite films were investigated using phenol (P), 2,4-dichlorophenol (2,4-DCP), 4-chlorophenol (4-CP) and 4-aminophenol (4-AP) as a model organic compounds under UV light irradiation. Hybrid semiconductor thin films showed a higher photocatalytic activity than single component ZnO, SnO 2 and In 2O 3 films. The substituted phenols degrade faster than phenol. The ease of degradation of phenols is different for each catalyst and the order of catalytic efficiency is also different for each phenol. The use of multiple components offered a higher control of their properties by varying the composition of the materials and related parameters such as morphology and interface. It was also found that the photocatalytic degradation of phenolic compounds on the composite films and single films followed pseudo-first order kinetics. 相似文献
10.
通过葡萄糖协助的水热以及随后的退火处理两步法成功制备了系列ZnO/In 2O 3复合空心球. X射线衍射谱(XRD)表明, 经500 ℃退火制得的ZnO/In 2O 3复合空心球中ZnO以非晶态存在, 但是随着退火温度的提高, 其逐渐转变为纤锌矿结构. 场发射扫描电子显微镜(FE-SEM)和透射显微镜(TEM)结果表明, ZnO/In 2O 3复合材料具有空心球结构, 复合纳米颗粒之间结合紧密. 将ZnO/In 2O 3复合空心球组装成薄膜光电极, 研究了其光电催化降解葡萄糖的性能. 结果表明, 700 ℃退火处理的ZnO/In 2O 3复合空心球薄膜电极可产生最高的光致电流密度. 通过光致发光光谱(PL)发现, 与ZnO或In 2O 3空心球相比, ZnO/In 2O 3复合空心球的发光强度猝灭效果明显. 这是由于复合材料中晶界处产生的p-n结电场, 降低了光生电子-空穴对的复合几率, 从而使更多的光生电子可迁移到电极表面. 相似文献
11.
The thick-film semiconductor sensor for liquid petroleum gas (LPG) detection was fabricated using a mixed WO 3-based sensor. We present the characterization of both their structural properties by means of XRD measurements and the electrical characteristics by using gas-sensing properties. The sensing characteristics such as sensitivity, working range, cross-sensitivity and response time were studied by using nanosized WO 3-based mixed with different metal oxides (SnO 2, TiO 2 and In 2O 3) and doped with noble metals (Au, Pd and Pt). The WO 3-based mixed with 5 wt.% In 2O 3 and 0.5 wt.% Pd showed the higher sensing characteristic at low concentration of LPG sensor at an operating temperature 225 °C. 相似文献
12.
The detection of low ozone concentrations in air (no higher than 120 ppb) using semiconducting films based on Fe 2O 3 · In 2O 3 obtained by laser ablation of the corresponding targets onto alumina substrates was studied. The temperature of the substrate during film deposition influenced their sensor properties. Temperature effects on the sensitivity of the films with respect to ozone were studied over the temperature range 200–380°C. Maximum sensitivity was reached at 250°C irrespective of the temperature of film deposition. The dependence of film sensitivity on the concentration of ozone in air was determined. At equal ratios between In 2O 3 and Fe 2O 3, the sensitivity of the sensor films prepared by laser ablation was much higher than that of thick-film sensors obtained from aqueous metal oxide suspensions by the stenciling technique. Possible reasons for the effects observed were considered. 相似文献
13.
Noble metal is usually used to improve the gas sensing performance of metal oxide semiconductor (MOS) due to its better catalytic properties. In this work, we reported a synthesis of Pd/ZnO nanocomposite by an in situ reduction with ascorbic acid (AA). It was found that Pd/ZnO sensor has excellent selectivity to CO and the response of the Pd/ZnO sensor towards 100 ppm CO was as high as 15 ( Ra/ Rg), obviously higher than that of the pristine ZnO sensor (1.4) when the working temperature is 220 °C. Moreover, the pure ZnO sensor almost has no selectivity to CO, but the Pd/ZnO sensor has excellent selectivity to CO, which may be ascribed to the electronic sensitization of Pd. Our present results demonstrate that the Pd can significantly improve the gas-sensing performance of metal oxide semiconductor and the obtained sensor has great potential in monitoring coal mine gas. 相似文献
14.
The activities of metal oxide CuO, SnO 2, CoO, Ag 2O, ZnO or noble metal Pt, Pd, Rh-doped In 2O 3/Al 2O 3 catalysts for selective catalytic reduction of NO by propene were investigated. The temperature windows for NO reduction
over noble metal-doped In 2O 3/Al 2O 3 catalysts were shifted and broaden slightly compared with single component catalyst alone.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
15.
以掺氟SnO 2 (FTO)导电玻璃为基底, 采用水热法制备了ZnO纳米棒阵列. 通过In(NO 3) 3水溶液水洗的方法, 合成了In 2O 3敏化ZnO纳米棒阵列光催化剂. 采用场发射扫描电子显微镜(FESEM), X射线能谱(EDX), X射线衍射(XRD)及紫外-可见漫反射光谱(UV-Vis DRS)对样品的形貌、结构、组成、晶相等进行一系列的表征. 以罗丹明B (RhB)为目标降解物, 探究了In 2O 3敏化ZnO 纳米棒阵列光电催化活性. 采用场诱导表面光伏技术(FISPV)研究了不同含量的In 2O 3敏化ZnO纳米棒阵列在光照射下的光生电荷行为. 结合电化学工作站检测不同样品的光电流, 随着In 2O 3敏化量的改变, 光电流和开路电压也随之改变. 并探讨了In 2O 3敏化ZnO纳米棒阵列光生电荷行为与光电催化活性之间的关系. 结果表明, 适量In 2O 3敏化的ZnO光催化剂在可见光下2 h内对罗丹明B的降解效率达到95%, 是单纯ZnO纳米棒阵列的2.4倍. 相似文献
16.
采用溶胶凝胶法制备了In20rCdln2O4和CdO-Cdln2O4纳米复合氧化物,利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对复合材料的形貌和结构进行表征,并对其进行了乙醇、丙酮等多种气体的气敏性能测试.结果表明Cdln2O4材料复合h12O3和CdO后显著提高了对丙酮和乙醇气体的灵敏度和选择性. 相似文献
17.
SnO 2, In 2O 3, and Sn-doped In 2O 3 (ITO)/polymer and the corresponding carbon composite hollow colloids are template synthesized. It is essential that the sulfonated
gel shell of the cross-linked polystyrene hollow colloid can favorably induce adsorption of target precursors. After being
calcined in air to remove the template, SnO 2, In 2O 3, and ITO hollow colloids are obtained. Because the cross-linked polymer gel can be transformed into carbon in nitrogen at
higher temperature such as 800 °C, metal oxide/carbon hollow colloids are consequently derived, whose shells are mesoporous.
The SnO 2-, In 2O 3-, and ITO-containing polymer or carbon composite hollow colloids will be promising in sensors, catalysts, and fuel cells
as electrode materials.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
18.
The hydrogen sensing performance of ceria-containing nanocrystalline indium and tin oxides is investigated for different concentrations of added ceria. The sensor response of nanocrytsalline In2O3 is considerably enhanced at low CeO2 concentrations. In contrast, low levels of CeO2 cause a substantial drop in the sensor response of SnO2-based composite; at a 3 wt % level of added ceria, its hydrogen sensing ability is almost entirely suppressed. Possible causes of these effects are investigated via X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. XPS data show that additions of CeO2 have different effects on the structure of the base oxides (In2O3 and SnO2), with implications for the hydrogen sensing performance of the composites. 相似文献
19.
The Ga 2O 3-Al 2O 3-ZnO (GAZ) multi-component spinel powders with incorporated Cu 2+, Co 2+, Fe 2+, Ni 2+, Mn 2+ and In 2+ metal cations were synthesized by co-precipitation method from a mixed solution of nitrate salts. Spinel crystal structure of each composition was confirmed by XRD measurements. The multi-component oxide powders were tested in the reduction of nitrogen oxide (NO) under lean conditions. Among the catalysts tested, In 2O 3-containing GAZ with a pure spinel phase structure showed promising catalytic activity in the NO reduction in the presence of 10% H 2O vapor. In addition, the effect of H 2O vapor and SO 2 on the selective reduction of NO over In 2O 3-GAZ/cordierite and In 2O 3-GAZ/metal honeycombs catalysts has been investigated. 相似文献
20.
The thick film semiconductor sensor for NO 2 gas detection was fabricated by screen-printing method using a mixed WO 3-based as sensing material. The sensing characteristics, such as response time, response linearity, sensitivity, working range, cross sensitivity, and long-term stability were further studied by using a WO 3-based mixed with different metal oxides (SnO 2, TiO 2 and In 2O 3) and doped with noble metals (Au, Pd and Pt) as sensing materials was observed. The highest sensitivity for low concentrations (<16 mg l −1) was observed using WO 3-based mixed with In 2O 3 or TiO 2. The NO 2 gas sensor showing the fastest response and recovery time (both within 2 min), good linearity ( Y=0.606 X+0.788 R2=0.991) for gas concentrations from 3 to 310 mg l −1, low resistance (3 MΩ), high sensitivity, undesirable cross sensitivity effect and good long-term stability (at least 120 days) using WO 3-SnO 2-Au as sensing material. 相似文献
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