纳米SnO2基气敏元件对甲醛气体的检测

采用溶胶-凝胶法制备了纳米SnO2粉末,利用X射线衍射仪(XRD)以及原子力显微镜(AFM)对材料的晶体结构及晶粒尺寸进行了表征.采用制备的纳米SnO2作为基底材料,掺杂纳米TiO2粉末(SnO2与TiO2的物质的量之比为9:1)以及少量的Ag+(物质的量百分比为0.2%～0.4%),以此材料制成气敏元件,检测了元件的甲醛气敏性能.结果表明:该元件在工作温度为300℃时,对200×10-6的甲醛具有较好的敏感性,在不同的工作温度下,元件表现出良好的气敏选择性.理论计算表明,气体分子轨道能量的差异是元件气敏选择性的定性因素.     

基于SnO2薄膜气体传感器的设计与制作（英文）

设计了一种带硅岛结构的基于SnO2薄膜材料的共面式气体传感器.利用有限元工具对传感器进行了稳态热分析,分析结果表明这种传感器在33.84 mW的功耗下最高温度达到400℃,气敏薄膜上温度分布均匀.详细阐述了传感器的制作过程,过程中总共使用4块掩模版用于光刻工艺.采用溶胶-凝胶法制备了SnO2纳米薄膜作为传感器的气敏元件.对传感器进行了气敏测试,实验结果表明该传感器拥有良好的气敏性能,在300℃下对50×10-6到2 000×10-6氢气的灵敏度逐渐递增,反应时间可控制在10 s以内.     

少量氧化锡掺杂提高三氧化钨探测H2S气体的气敏性能

为改善WO3基敏感材料的气敏性能,先采用液相还原法制备得到WO3粉体,再通过微波辅助液相法制备了SnO2掺杂量为0.5%、1%、3%、5%、10%(质量分数,下同)的SnO2-WO3复合材料。采用XRD和SEM对材料的物相、形貌进行了表征,并研究了掺杂SnO2对WO3气敏性能的影响。结果表明,掺杂3%的SnO2可显著提高WO3对H2S的灵敏度和选择性,在工作温度为160℃时,元件对体积浓度为10×10-6 H2S的灵敏度达65,对体积浓度为50×10-6 H2S的灵敏度高达169,且灵敏度与气体浓度呈现良好的线性关系。此外,纯WO3和SnO2(3%)-WO3材料在相对湿度RH=22%～64%时有良好的抗湿性。     

粉末溅射平面薄膜型SnO2/CeO2酒敏元件性能测试

给出了SnO2/10?O2(0.4mm×0.6mm×0.4mm)元件的温耗特性曲线,研究了老化的温度和时间,研究了气敏电流Ig与气体浓度C的关系,并给出了一个普遍适用的规律.     

Development of sensors based on CuO-doped SnO2 hollow spheres for ppb level H2S gas sensing

An effort has been made to develop a new kind of SnO₂–CuO gas sensor which could detect an extremely small amount of H₂S gas at relatively low working temperature. The sensor nanomaterials were prepared from SnO₂ hollow spheres (synthesized by employing carbon microspheres as temples) and Cu precursor by dipping method. The composition and structural characteristics of the as-prepared CuO-doped SnO₂ hollow spheres were studied by X-ray photoelectron spectroscopy, X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy. Gas-sensing properties of CuO-doped SnO₂ hollow sphere were also investigated. It was found that the sensor showed good selectivity and high sensitivity to H₂S gas. A ppb level detection limit was obtained with the sensor at the relatively low temperature of 35 °C. Such good performances are probably attributed to the hollow sphere nanostructures. Our results imply that materials with hollow sphere nanostructures are promising candidates for high-performance gas sensors.     

Ultrahigh Responsivity UV Photodetector Based on Cu Nanostructure/ZnO QD Hybrid Architectures

Strong near‐surface electromagnetic field formed by collective oscillation of electrons on Cu nanostructure a shows a strong dependence on geometry, offering a promising approach to boost the light absorption of ZnO photoactive layers with enhanced plasmon scattering. Here, a facile way to fabricate UV photodetectors with tunable configuration of the self‐assembled Cu nanostructures on ZnO thin films is reported. The incident lights are effectively confined in ZnO photoactive layers with the existence of the uplayer Cu nanostructures, and the interdiffusion of Cu atoms during fabrication of the Cu nanostructures can improve the carrier transfer in ZnO thin films. The optical properties of the hybrid architectures are successfully tailored over a control of the geometric evolution of the Cu nanostructures, resulting in significantly enhanced photocurrent and responsivity of 2.26 mA and 234 A W^?1 under a UV light illumination of 0.62 mW cm^?2 at 10 V, respectively. The photodetectors also exhibit excellent reproducibility, stability, and UV–visible rejection ratio (R_{370 nm}/R_{500 nm}) of ≈370, offering an approach of high‐performance UV photodetectors for practical applications.     

Sol-gel法制备CuSO4,Cu(AC)2掺杂SnO2的气敏性能研究

以溶胶-凝胶法(Sol-gel)制备纳米SnO2及其不同比例的铜源掺杂物.采用热分析(TG-DTA),XRD等手段对其产物进行表征,利用静态配气法测试了掺杂产物的气敏性能.实验结果表明:采用Sol-gel法制备掺杂SnO2的气敏性能,同时受铜源和掺杂量的影响,且掺杂产物对乙醇不很敏感,但在150℃工作温度下对0.005%的H2S具有36367倍的高灵敏度.     

GIT插层材料微观结构及对SnO2基体气敏性能的影响

合成了具有微观层状结构的纳米级氧化石墨,并在100℃以下通过插层反应制备得氧化石墨插层SnO2(GIT),也具有层状结构;通过AFM、FE-SEM、XRD、DSC-TG对其形貌、微观结构、物相、热性能进行分析;在SnO2基体材料中掺入适量GIT插层材料,经过适当的热处理,制备GIT-SnO2复合气敏元件.气敏性能测试表明,材料具有较低的电阻,在200-300℃范围内对丁烷具有较高的灵敏度.     

粉末溅射平面薄膜型SnO2/CeO2酒敏元件

介绍了用粉末溅射做出的两种平面薄膜型酒敏元件的工艺、芯片结构和基本参数测试的结果.     

Enhanced H2S gas sensing properties of multiple-networked Pd-doped SnO2-core/ZnO-shell nanorod sensors

Pd-doped SnO₂-core/ZnO-shell nanorods were synthesized by using a three-step process: thermal evaporation of Sn powders in an oxygen atmosphere, atomic layer deposition of ZnO, and Pd diffusion followed by annealing. The sensitivity of the multiple networked SnO₂-core/ZnO-shell nanorod sensor to H₂S gas was found to be improved further significantly by Pd doping. The Pd-doped SnO₂-core/ZnO-shell nanorod sensor showed sensitivities of 6.4, 15.4, and 36.2% at H₂S concentrations of 20, 50, and 100 ppm at room temperature. The sensitivity of the nanorods was improved by more than 10 times at a H₂S concentration of 100 ppm. The sensitivity enhancement of the SnO₂-core/ZnO-shell nanorods by Pd doping may be attributed to the spillover effect, active reaction site generation, and the enhancement of chemisorption and dissociation of gas.     

Conductometric Hydrogen Gas Sensor Based on Polypyrrole Nanofibers

Polypyrrole nanofibers are synthesized through a template-free chemical route and used as the active component for hydrogen gas sensing at room temperature. The synthesis of polypyrrole nanofibers was achieved by using bipyrrole as an initiator to speed up the polymerization of pyrrole with FeCl as the oxidizing agent. Scanning and transmission electron microscopy studies indicate that the resulting polypyrrole forms a nanofibrous mat with average nanofiber diameter of 18 nm. Fourier transform infrared spectroscopy and elemental analysis confirms that the structure of the nanofibers is comparable to bulk polypyrrole. Gas sensing properties of polypyrrole nanofibers were investigated by depositing nanofiber dispersions on an interdigited conductometric transducer. The sensor performance was tested through programmable exposure towards different concentrations of hydrogen gas diluted in synthetic air in an environmental cell at different temperatures. A short response time of 43 s was observed upon exposure to a concentration of 1% hydrogen with a decrease in film resistance of 312 at room temperature. The sensor sensitivity was analyzed with gradual elevation of the operating temperature.     

Ni修饰层对SnO2薄膜气敏性能影响

采用磁控溅射技术在SnO2薄膜表面修饰金属Ni，研究Ni修饰量对SnO2薄膜气敏性能影响。对Ni-SnO2薄膜进行表面成分分析，发现Ni的表面含量和化学价态对Ni-SnO2薄膜气敏性能影响至关重要。Ni的表面修饰量在3．4％-8．8％之间将有效提高SnO2薄膜对低浓度氢气的敏感性能。180℃工作温度下，表面含Ni3．4％的SnO2薄膜对1000ppm的氢气灵敏度最高为59．6，同时响应时间和恢复时间降低至15s和125s。Ni修饰量增加到23．4％，薄膜的气敏性能恶化，这是因为修饰层过厚，阻碍气体与SnO2材料接触。同时，XPS证实NiO是增加SnO2薄膜气敏性能的主要物质，增敏机理解释为Ni氧化后形成的NiO在SnO2薄膜上形成p-n结，促进元件的电导变化，从而提高了薄膜的气敏性能。     

Effect of thickness on nanostructured SnO2 thin films by spray pyrolysis as highly sensitive H2S gas sensor

Nanostructured SnO2 thin films were prepared by spray pyrolysis technique onto glass substrates with different thickness by varying quantity of precursor solution. The structural, optical and electrical properties of these films have been studied. The crystallographic structure of the films was studied by X-ray diffraction (XRD). It is found that the films are tetragonal with (110) orientation. The grain size increases with thickness. Atomic Force Microscopy (AFM) showed that the nanocrystalline nature of the films with porous nature. The grain size increased 14 to 29 nm with increase in film thickness. The studies on the optical properties show that the direct band gap value decreases from 3.75 to 3.50 eV. The temperature dependence of the electrical conductivity was studied. The activation energies of the films are calculated from the conductance temperature characteristics. The nanostructured SnO2 thin films were used as sensing layers for resistive gas sensors. The dependence of gas sensing properties on the thickness of SnO2 thin films was investigated. The gas response of the SnO2 thin films towards the H2S gas was determined at an operating temperature of 150 degrees C. The sensitivity towards H2S gas is strongly depending on surface morphology of the SnO2 thin films.     

High sensitivity and switching-like response behavior of SnO2-Ag-SnO2 element to H2S at room temperature

SnO₂ thin films were prepared using SnCl₄ and O₂ as precursors by means of the plasma enhanced chemical vapor deposition method (PECVD), and were modified with silver (Ag) by a soaking technique to form a SnO₂-Ag-SnO₂ element. The characteristics of this element were found to depend on the operating temperature and H₂S concentration. This element proved to be highly sensitive and selective to H₂S at room temperature (20 °C). Furthermore, its response speed was fairly high at this temperature. The gas sensing mechanism of the SnO₂-Ag-SnO₂ element to H₂S is also discussed.     

Atomically Dispersed Electron Traps in Cu Doped BiOBr Boosting CO2 Reduction to Methanol by Pure H2O

Overall photocatalytic conversion of CO₂ and pure H₂O driven by solar irradiation into methanol provides a sustainable approach for extraterrestrial synthesis. However, few photocatalysts exhibit efficient production of CH₃OH. Here, BiOBr nanosheets supporting atomic Cu catalysts for CO₂ reduction are reported. The investigation of charge dynamics demonstrates a strong built-in electric field established by isolated Cu sites as electron traps to facilitate charge transfer and stabilize charge carriers. As result, the catalysts exhibit a substantially high catalytic performance with methanol productivity of 627.66 µmol g_catal⁻¹ h⁻¹ and selectivity of ≈90% with an apparent quantum efficiency of 12.23%. Mechanism studies reveal that the high selectivity of methanol can be ascribed to energy-favorable hydrogenation of *CO intermediate giving rise to *CHO. The unfavorable adsorption on Cu₁@BiOBr prevents methanol from being oxidized by photogenerated holes. This work highlights the great potential of single-atom photocatalysts in chemical transformation and energy storage reactions.     

基于Na3Zr2Si2PO12固体电解质的非平衡态SO2传感器

基于Na₃Zr₂Si₂PO₁₂(NASICON)固体电解质, 分别以Na₂SO₄-BaSO₄混合盐和NaRe(SO₄)₂复盐为敏感电极材料制备了片式SO₂非平衡态气体传感器。结果表明, 该类型传感器的输出电动势与SO₂气体浓度的对数呈良好的线性关系, 在低温260℃具有最佳性能, 灵敏度分别达到了160 mV/decade和136 mV/decade。传感器在不同浓度的SO₂气体中的交流阻抗谱测试结果显示, 气体在敏感电极的三相界面处电化学反应的活性随着气体浓度的增大而增强, 结合敏感电极结构, 对该类敏感电极的机理进行了分析。由于NASICON具有良好的低温钠离子导电性, 可以大幅降低传感器的工作温度; 由于Na₂SO₄-BaSO₄混合盐和NaRe(SO₄)₂敏感材料具有更好的化学稳定性, 制备的传感器具有良好的可重复性和稳定性。基于非平衡态设计的传感器, 具有结构简单和成本低的优点。以上特性为该传感器在SO₂气体在环境监测方面的应用提供了可能。