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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
E.N. ArmstrongAuthor VitaeT. StrikerAuthor Vitae V. RamaswamyAuthor VitaeJ.A. RuudAuthor Vitae E.D. WachsmanAuthor Vitae 《Sensors and actuators. B, Chemical》2011,158(1):159-170
NOx adsorption behavior on LaFeO3 (LFO) and LaMnO3+δ (LMO) was characterized using temperature controlled methods and mass spectrometry. Temperature program desorption revealed decomposition of complex surface species formation when NO or NO2 was adsorbed on LFO and LMO. LFO exhibited higher adsorption capacity for NOx species than LMO and was shown to be more active for NOx surface conversion. Both effects were attributed to the different B-site cations, with iron in LFO in the 3+ valence state, and manganese in LMO in the 3+ and 4+ valence states. Results from diffuse reflectance infrared spectroscopy were used to identify specific nitrite and nitrate species that are formed on the surfaces of LFO and LMO at room temperature. Temperature programmed reaction revealed a complex NO2 decomposition mechanism to NO and O2 for LFO and LMO in which the formation of nitrite and nitrate species serve as intermediates below ∼600 °C. NOx sensing mechanisms were considered and predicted based on the types and quantities of surface species formed. 相似文献
992.
Jiarui HuangAuthor Vitae Youjie WuAuthor VitaeCuiping GuAuthor Vitae Muheng ZhaiAuthor VitaeYufeng SunAuthor Vitae Jinhuai LiuAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(1):126-133
Hierarchically three-dimensional (3D) porous ZnO architectures are synthesized by a template-free, economical aqueous solution method combined with subsequent calcination. First, the precursors of interlaced and monodisperse basic zinc nitrate (BZN) nanosheets are prepared. Then calcination of the precursors produces hierarchically 3D porous ZnO architectures composed of interlaced ZnO nanosheets with high porosity resulting from the thermal decomposition of the precursors. The products are characterized by X-ray diffraction, thermogravimetric-differential thermalgravimetric analysis, scanning electron microscopy, transmission electron microscopy, and Brunauer-Emmett-Teller N2 adsorption-desorption analyses. The BET surface area of the hierarchically porous ZnO nanostructures was calculated to be 12.8 m2 g−1. Compared with ZnO rods, the as-prepared porous ZnO nanosheets exhibit a good response and reversibility to some organic gases, such as ethanol and acetone. The responses to 100 ppm ethanol and acetone are 24.3 and 31.6, respectively, at a working temperature of 320 °C. These results show that the porous ZnO architectures are highly promising for gas sensor applications, as the gas diffusion and mass transportation in sensing materials are significantly enhanced by their unique structures. Moreover, it is believed that this solution-based approach can be extended to fabricate other porous metal oxide materials with a unique morphology or shape. 相似文献
993.
Ko-ichiro Miyamoto Torsten Wagner Shuhei MimuraShin’ichiro Kanoh Tatsuo Yoshinobu Michael J. Schöning 《Sensors and actuators. B, Chemical》2011,154(2):119-123
The constant-phase-mode operation of the light-addressable potentiometric sensor (LAPS) is proposed and demonstrated. In this new operation mode, the temporal change and the spatial distribution of the analyte concentration are recorded in the form of the bias voltage applied to the LAPS sensor plate, which is servo-controlled to maintain the phase of the photocurrent at a constant value with respect to the light modulation. The constant-phase-mode LAPS is advantageous for its wider measurement range and reduction of artifacts. 相似文献
994.
D. ZilliAuthor VitaeP.R. BonelliAuthor Vitae A.L. CukiermanAuthor Vitae 《Sensors and actuators. B, Chemical》2011,157(1):169-176
Multi-walled carbon nanotubes (MWCNTs) are successfully processed in the form of thin films (buckypapers), and their morphology and electrical behaviour are characterized. The MWCNTs are synthesized by the floating catalyst chemical vapour deposition process. The effects of a sequence of treatments applied for MWCNTs purification on the buckypapers electrical behaviour are also examined. Nanocomposite thin films constituted of pristine and purified MWCNTs and Pd nanoparticles are prepared in order to evaluate their viability as H2 sensors at room temperature. For this purpose, the electrical resistance of the nanocomposite films in atmospheres with different H2 concentrations, is determined. Scanning electron microscopy (SEM) images show that the buckypapers and the nanocomposite films are 2D structures constituted by randomly oriented MWCNTs. The buckypapers present a semiconductor-like electrical behaviour as determined by the standard four point method. Room temperature resistivity values of around 10−3 Ω m are assessed. Nanocomposite films show different electrical behaviour depending on the purification treatment applied to the MWCNTs employed. Furthermore, the electrical resistance of the nanocomposite films is found to increase when the measurements are performed in H2 atmosphere. Values of H2 sensitivity at room temperature of the nanocomposite films up to 2.15% are determined for H2 average concentration higher than 350 ppm with short recovery time. 相似文献
995.
Satish S. BadadheAuthor VitaeI.S. MullaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,156(2):943-948
A facile spray pyrolysis route is used to deposit aluminium doped ZnO (AZO) thin films on to the glass substrates. It is observed that on aluminium doping the particle size of ZnO reduces significantly; moreover, uniformity of particle also gets enhanced. Their XRD study reveals that intensity ratio of crystal planes depend on the aluminium doping concentration. The gas response studies of; ∼800 nm thick Al-doped ZnO films at different operating temperatures show that 5 at% Al-doped ZnO thin film exhibits highest response towards H2S gas at 200 °C. The results suggest that the gas response strongly depends on the particle size and aluminium doping in the ZnO. 相似文献
996.
Interaction of CO with hydrous ruthenium oxide and development of a chemoresistive ambient CO sensor
Adedunni AdeyemoAuthor VitaeGary HunterAuthor Vitae Prabir K. DuttaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,152(2):307-315
Hydrated ruthenium oxide (RuOx(OH)y), the material of interest in this study was prepared by reaction of an aqueous solution of ruthenium chloride with base. This material was amorphous, made up of 20-50 nm particles and contains Ru(III) and Ru(IV), as determined by X-ray photoelectron spectroscopy. The conductivity of thick films of RuOx(OH)y decreased in the presence of CO in a background of air and this change was reversible. Infrared spectroscopy showed the formation of carbonates in the presence of CO, which disappeared upon replacement of CO with O2. Upon heating RuOx(OH)y, there was a gradual conversion to crystalline RuO2 beyond 200 °C. With these heated materials, the resistance change in the presence of CO at room temperature also gradually diminished. We propose that oxidation of CO on RuOx(OH)y leads to reduction of the ruthenium and a decrease in conductivity. With the conversion to crystalline RuO2 upon heating, the material becomes metallic and conductivity changes are diminished. The change in conductivity of RuOx(OH)y with CO provides a convenient platform for an ambient CO sensor. Such a device also does not show interference from hydrocarbons (2000 ppm), ammonia (150 ppm), CO2 (2000 ppm), NO (15 ppm) and NO2 (15 ppm). 相似文献
997.
A. IadiciccoAuthor VitaeD. PaladinoAuthor Vitae S. CampopianoAuthor VitaeW.J. BockAuthor Vitae A. CutoloAuthor VitaeA. CusanoAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(2):903-908
A novel refractive index sensing scheme based on evanescent wave interaction through locally and permanently bent single mode optical fibers is proposed. Local and permanent bends in single mode optical fibers enable significant power coupling between core and cladding modes. Order and number of excited cladding modes depend on bend features and determine the field profile at the output of the bent region. This in turn constitutes a simple mechanism to tailor the field distribution in single mode optical fibers useful for spatial light modulation. Moreover, since guided cladding modes are strongly influenced by the surrounding refractive index (SRI), the power transmitted at the output of the bent region as well as its dependence on the optical wavelength are strongly sensitive to the SRI opening new scenarios in sensing applications. 相似文献
998.
Li ShenAuthor VitaeMichael RattermanAuthor Vitae David KlotzkinAuthor VitaeIan PapautskyAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(1):430-435
This work describes a stable and sensitive optical oxygen sensor based on a consumer CMOS image sensor array and polarization signal isolation. The consumer CMOS image sensor is inherently color discriminating, while the polarization is a wavelength-independent scheme for filtering excitation light. Combination of these two components generates a compact, multi-color detection system applicable to luminescence-based sensing. The optical system is applied to point-of-use oxygen sensing based on quenching of platinum octaethylporphine (PtOEP) luminophore. Sensitivity of the demonstrated portable oxygen sensor is comparable to that of benchtop spectroscopy-based systems. Taking advantage of the spatial resolution of the CMOS image sensor, an oxygen insensitive reference can be integrated to improve the reliability when powered by a battery. The low-cost and high sensitivity of the demonstrated optical sensing approach make it promising for point-of-use applications. 相似文献
999.
Huitao FanAuthor VitaeTong ZhangAuthor Vitae Xiujuan XuAuthor VitaeNing LvAuthor Vitae 《Sensors and actuators. B, Chemical》2011,153(1):83-88
N-type Fe2O3 nanobelts and P-type LaFeO3 nanobelts were prepared by electrospinning. The structure and micro-morphology of the materials were characterized by X-ray diffraction (XRD) and scanning of electron microscopy (SEM). The gas sensing properties of the materials were investigated. The results show that the optimum operating temperature of the gas sensors fabricated from Fe2O3 nanobelts is 285 °C, whereas that from LaFeO3 nanobelts is 170 °C. Under optimum operating temperatures at 500 ppm ethanol, the response of the gas sensors based on these two materials is 4.9 and 8.9, respectively. The response of LaFeO3-based gas sensors behaves linearly with the ethanol concentration at 10-200 ppm. Sensitivities to different gases were examined, and the results show that LaFeO3 nanobelts exhibit good selectivity to ethanol, making them promising candidates as practical detectors of ethanol. 相似文献
1000.
A distributed Bragg reflector porous silicon layer for optical interferometric sensing of organic vapor 总被引:1,自引:0,他引:1
Han-Jung KimAuthor Vitae Young-You KimAuthor Vitae Ki-Won LeeAuthor VitaeSeon-Hwa ParkAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(2):673-678
In this study, we successfully demonstrated the rapid, sensitive, and reversible sensing of organic vapor using a distributed Bragg reflector (DBR) porous silicon (PS) layer. We fabricated the DBR PS layer on a p+-type silicon substrate and investigated its reflectance spectra before, during, and after exposure to the different concentrations of various organic vapors. When the DBR PS layer sample was exposed to methanol, acetone, ethanol, and isopropanol vapors, the maximum reflectance peak promptly shifted toward longer wavelengths by about 4.5, 23.2, 26.0, and 38.2 nm, respectively. We determined that the red-shift in the reflectance spectrum could be attributed to the changes in the refractive index induced by the capillary condensation of the organic vapor within the pores of the DBR PS layer. The DBR PS layer showed excellent sensing ability under the different concentrations and types of organic vapors. In addition, a slight hysteresis of the red-shift was observed during repeated exposure to organic vapors at different concentrations. After removing the organic vapors, the reflectance spectrum promptly returned to its original state. 相似文献