ZnO纳米线CO气敏性能与气体浓度的关系研究

以采用物理热蒸发法制备的纯ZnO纳米线和掺杂Ni、Al的ZnO纳米线为气敏基料,以蒸馏水调和制备成旁热式气敏元件,用静态配气法对一系列浓度的一氧化碳气体进行了气敏性能的测试。结果表明掺杂的纳米ZnO元件与纯的纳米ZnO元件相比对CO气体的灵敏度更高,三种元件的灵敏度与所测气体浓度均呈现先上升后下降的变化趋势,且在同一浓度下出现最高值。     

Ag掺杂对ZnO纳米线气敏性能的影响

以采用物理热蒸发法制备的纯ZnO纳米线和Ag掺杂ZnO纳米线为气敏基料，制备成旁热式气敏元件，用静态配气法对浓度均为100ppm的无水乙醇蒸汽、氨气、甲烷及一氧化碳四种气体进行气敏性能测试，结果表明，Ag掺杂后，ZnO纳米线对四种气体灵敏度的最高值分别提高了230％，92％，158％，49％，缩短了响应时间和恢复时间。     

Ni掺杂对ZnO纳米线甲烷气敏性能的影响

以采用物理热蒸发法制备的纯ZnO纳米线和Ni掺杂ZnO纳米线为气敏基料，制备成旁热式气敏元件，用静态配气法对浓度为10^-4的甲烷气体进行了气敏性能的测试．结果表明Ni掺杂使ZnO纳米线对甲烷灵敏度提高了182％，响应时间和恢复时间分别缩短了3和2s．Ni的掺杂，在ZnO半导体禁带中引入新的复合中心，形成附加能级，提高了ZnO纳米线对甲烷的灵敏度．     

氧化钨厚膜气敏传感器的气氛改性研究

采用丝网印刷法将钨酸分解得到的氧化钨粉末制备成氧化钨厚膜气敏传感器,并先后在氢气和空气气氛中进行还原和氧化处理,系统研究了氢气浓度和氧化时的升温速率对敏感膜的形貌、结构和CO气敏性能的影响.结果表明,经氢气还原-空气氧化后,敏感膜表面形貌由近似球形的颗粒转化为表面光滑两端开口的集束棒状或规则的四方柱状,而晶体结构则没有发生改变.敏感膜对CO的灵敏度(Rair/RCO)随CO浓度的增加和测试温度的升高而增大.与没有进行气氛改性的敏感膜相比,经10%H2气氛还原并在600℃空气中以5℃/min氧化处理后的敏感膜对CO具有最大的灵敏度,其对3.8×10-5CO的灵敏度提高了13.3倍.即通过对敏感膜进行气氛改性可显著提高对CO的敏感性能.     

低工作温度的氧化钨气敏材料

本文报道了一种可以在１００℃左右工作的氢化钨气敏材料，它对氢气和一氧化氮有很高的灵敏度和良好的选择性，并可对空气中的一氧化氮进行探测     

三维石墨烯/聚苯胺纳米线复合材料合成及室温气敏性能

以三维石墨烯和苯胺为原料,使用化学氧化聚合法制备二元复合材料三维石墨烯/聚苯胺纳米线(3D-rGO/PANI),石墨烯既是气敏材料的组成部分,又是聚苯胺的生长模板。复合材料的结构表征使用扫描电镜、红外光谱仪和比表面测试仪。结果表明:PANI是线状结构,复合材料有大量空隙,比表面积大。室温下,和纯PANI相比,3D-rGO/PANI对H2表现出较好的气敏性能,H2浓度为500×10-6时,灵敏度达到10.6。复合材料的大比表面积和协同效应有助于气敏性能提高。     

导电聚合物纳米线的制备及气敏性能研究

首次采用简单的浸润多孔氧化铝(AAO)模板法制备了导电聚合物聚-3,4-乙烯二氧噻吩(PE-DOT)纳米线.导电聚合物溶液浸润AAO模板后,PEDOT吸附于孔道壁并进一步聚合生成导电聚合物纳米线.紫外-可见光-近红外光谱(UV-vis-NIR spec-trum)分析表明生成的纳米线处于掺杂态.采用四探针仪分析了导电聚合物纳米线的导电性能,结果显示纳米线电导率相比普通PEDOT材料有数量级增加,且表现出良好的掺杂/脱掺杂能力.研究了导电聚合物纳米线的气体敏感性能,发现其对挥发性醇类,尤其对甲醇在较低浓度下表现出优异的敏感性,对5×10-6甲醇气体的响应时间约为10～20s,测试可重复性超过20次,达到饱和吸附时的气体浓度明显大于普通PEDOT材料.表明PEDOT纳米线不仅提供了较大表面积供气体分子吸附,而且纳米线中导电通道取向一致,从而体现出较好的气体敏感性能.     

氧化钨基半导体气体传感器的研究进展

近年来,氧化钨(WO_3)基半导体气体传感器由于可用来检测低浓度二氧化氮、二氧化硫、臭氧和氨气等气体而受到广泛关注。将WO_3基材料分为4类:纯WO_3材料、氧化物-WO_3复合材料、贵金属-WO_3复合材料和有机物-WO_3复合材料,总结近年来中外文献中WO_3基材料对不同气体的响应性能,展现近年来国内外WO_3基半导体气体传感器的研究进展。最后根据已有的工作进展,提出合成新型纳米材料、降低工作温度、提高传感器选择性应成为WO_3基半导体气体传感器下一阶段的研究重点。     

Ag掺杂ZnO纳米线酒敏性能的研究

利用浸渍法将ZnO纳米线浸渍于AgNO3溶液中制备了Ag 掺杂的ZnO纳米线.借助X射线衍射仪(XRD)和场发射扫描电子显微镜(FESEM)对纳米线的晶体结构和形貌进行了表征.结果表明纳米线既含面心立方结构的Ag又含有六方纤锌矿结构的ZnO.三维网络结构的ZnO纳米线被一层致密的Ag颗粒包裹并在其表面形成了大量的具有高比表面剂的孔洞结构.将纯的和Ag掺杂的ZnO 纳米线都作为酒敏传感材料,在酒精浓度为0.001%,工作温度为150～400℃的范围内测试了它们的气敏特性,结果显示,Ag掺杂的ZnO纳米线的酒精灵敏度比纯ZnO纳米线提高了14.在工作温度为350℃的条件下测试了它们的响应-恢复时间.气敏元件的酒敏特性主要归结于表面吸附效应.     

ZnO纳米线气敏元件对单一气体浓度的判定研究

以不同金属掺杂的ZnO纳米线为气敏材料,在350℃下对不同浓度的H2气体进行了气敏性能测试.结果表明,掺杂Ag的ZnO纳米线在H2浓度为2.52×10(-3)时具有较高的气体灵敏度28.549.同时,利用Origin软件对测得的气敏性能曲线进行线性拟合,对未知的H2浓度进行了有效判定.还对金属掺杂提高ZnO纳米线气敏性...     

Nitrogen-doped tungsten oxide nanowires: low-temperature synthesis on Si, and electrical, optical, and field-emission properties

Very dense and uniformly distributed nitrogen-doped tungsten oxide (WO(3)) nanowires were synthesized successfully on a 4-inch Si(100) wafer at low temperature. The nanowires were of lengths extending up to 5 mum and diameters ranging from 25 to 35 nm. The highest aspect ratio was estimated to be about 200. An emission peak at 470 nm was found by photoluminescence measurement at room temperature. The suggested growth mechanism of the nanowires is vapor-solid growth, in which gaseous ammonia plays a significant role to reduce the formation temperature. The approach has proved to be a reliable way to produce nitrogen-doped WO(3) nanowires on Si in large quantities. The direct fabrication of WO(3)-based nanodevices on Si has been demonstrated.     

CO gas sensing of Pd-doped ZnO nanofibers synthesized by electrospinning method

Pure and Pd-doped ZnO nanofibers were synthesized by electrospinning method, and characterized via X-ray diffraction (XRD) and scanning electron microscopy (SEM). The diameters of the fibers annealed at 600 °C range from 70 to 160 nm. Compared with pure ZnO nanofiber sensor, the Pd-doped ZnO nanofiber sensor exhibits improved sensing properties to CO at 220 °C. Moreover, this sensor processes considerable sensitivity to low concentration CO in the range of 1-20 ppm with good selectivity. The response and recovery times are in the range of 25-29 s and 12-17 s, respectively. The sensing mechanism is also discussed.     

CO sensing devices based on indium oxide nanoparticles prepared by laser ablation in water

A simple and effective solution route for synthesizing colloidal indium oxide (In₂O₃) nanocrystallites, i.e. laser ablation in liquid (LAL), is reported. The morphology and chemical structure of the as-prepared samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS). The results showed the formation of In₂O₃ nanoparticles with a bimodal distribution, consisting mainly of particles of small diameters (2-5 nm). Sensor devices prepared by spraying directly the LAL colloidal solutions on interdigitated alumina substrates exhibited good sensing properties for the detection of CO at very low concentrations.     

氧化石墨烯的制备及其对NH3的敏感特性研究

石墨烯独特的原子结构赋予其电学、热学、力学等方面的优异性能,在诸多领域具有广泛的应用。氧化石墨烯不仅具有石墨烯结构特点,而且具有大量的含氧官能团,增强了对气体的吸附能力,更适合应用于气敏传感器。通过改进的Hummer方法制备了片状多层氧化石墨烯,并对不同浓度的NH3进行敏感特性测试。结果表明氧化石墨烯对NH3具有良好的响应,在(1.5～3.5)×10-4范围内呈线性关系。     

网状纤维结构氧化镍的制备及其气敏性能

p型半导体金属氧化物作为气敏材料具备响应快速、选择性高的特点,用于气体传感器的制备与开发。静电纺丝法可制备具有丰富气体吸附位点的网状结构材料,增强材料的气体敏感特性。以聚乙烯吡咯烷酮(PVP)、四水合乙酸镍为原料,采用静电纺丝法制备具有网状纤维结构的p型半导体氧化镍。通过X射线衍射、扫描电镜、X射线光电子能谱和比表面积测试等分析技术对材料的结构、形貌、组成和比表面等性能进行表征,并对其气敏性能进行测定,考察煅烧温度对材料气敏性能的影响。结果表明:煅烧温度为500℃时获得的氧化镍组装成气体传感器,在工作温度为250℃时,该元件对50mg/L丙酮气体表现出快速响应特性(响应时间为5s)、良好选择性和稳定性。     

Aligned tungsten oxide nanowires on tungsten (100) substrates

WO₃ nanowires in body center cubic structure were grown on W (100) substrates by heating in an argon atmosphere. Scanning electron microscope and transmission electron microscope characterizations show the WO₃ NWs grew along the [100] crystallographic orientation and were aligned in three directions. The diameter of WO₃ NWs is in the range of several to 20 nm and the length is up to 1 µm. Field emission measurements show that the field emission current density can reach 1.8 mA/cm² under electrical field 10 V/µm and the turn-on field can be as low as 2.6 V/µm.     

Large-scale, hot-filament-assisted synthesis of tungsten oxide and related transition metal oxide nanowires

A scalable and versatile method for the large-scale synthesis of tungsten trioxide nanowires and their arrays on a variety of substrates, including amorphous quartz and fluorinated tin oxide, is reported. The synthesis involves the chemical-vapor transport of metal oxide vapor-phase species using air or oxygen flow over hot filaments onto substrates kept at a distance. The results show that the density of the nanowires can be varied from 10(6)-10(10) cm(-2) by varying the substrate temperature. The diameter of the nanowires ranges from 100-20 nm. The results also show that variations in oxygen flow and substrate temperature affect the nanowire morphology from straight to bundled to branched nanowires. A thermodynamic model is proposed to show that the condensation of WO(2) species primarily accounts for the nucleation and subsequent growth of the nanowires, which supports the hypothesis that the nucleation of nanowires occurs through condensation of suboxide WO(2) vapor-phase species. This is in contrast to the expected WO(3) vapor-phase species condensation into WO(3) solid phase for nanoparticle formation. The as-synthesized nanowires are shown to form stable dispersions compared to nanoparticles in various organic and inorganic solvents.