氯化铜掺杂的多壁碳纳米管对甲醛的气敏响应研究

按照一定的质量比将CuCl2与多壁碳纳米管悬浊液超声掺杂.将纯的多壁碳纳米管悬浊液和掺杂后的碳管悬浊液分别旋涂在真空溅射的叉指金电极上,干燥后作为气敏膜.分别检测两组气敏膜暴露于甲醛气体前后的电流变化,并计算其灵敏度.掺杂后的多壁碳管气敏膜的灵敏度显著提高,且响应与恢复时间均明显缩短;室温下该传感器的响应非常稳定.CuCl2掺杂所导致的多壁碳管结构缺陷的增加可能是提高掺杂后碳管气敏响应的重要因素.     

多壁碳纳米管湿敏传感器的研究

传感器的基底为Al板电化学氧化成Al2O3绝缘层模板,上面真空溅射了叉指金电极,在电极之间旋涂微量多壁碳纳米管的水悬浊液,干燥后作为敏感膜.室温下测试传感器暴露在不同湿度的电阻变化,发现吸附了H2O后传感器的导电能力降低,且下降的幅度与被测湿度有良好的梯度关系.同时该多壁碳纳米管再经缩合剂EDC修饰后旋涂于电极上形成的敏感膜对湿度呈指数级变化.对它们的湿敏响应的机理进行了一些初步的探讨.     

电流型二氧化碳气敏微电极的研究

本文提出并用微电极技术建立了基于室温下直接阴极还原CO_2的电流型二氧化碳气敏微电极.微CO_2电极体系由金(或铂)微工作电极、Ag/AgCl对电极(兼作参比电极)、含有非水电解质[二甲基亚砜(DMSO)和四乙基氯化铵(0.1mol·L~(-1))的支持芯及透气膜构成.该电极在0～100%CO_2的整个浓度范围内有良好的线性响应关系,与现有的CO_2气敏器件比较,它具有灵敏度高、响应速度快、工作稳定和整体性好等特性.这类采用非水电解质的电流型气敏微电极能被开发应用于室温检测其它非电化学活性气体.文中还根据微电极工作原理讨论了这种气敏器件的响应机制.     

基于随机共振的纳米碳管气体传感器的研究

基于气体电晕放电原理,利用纳米碳管独特的物理结构和尖端发射效应,提出了一种新型的纳米碳管离子型气体传感器.采用阳极氧化铝模板法生长的定向纳米碳管阵列所构成的传感器,纳米碳管和电极是一体的,简化了器件结构和工艺.在外加直流电压激励下,纳米碳管顶部形成很强的非均匀电场,在电压相对低的情况下能很容易地电离气体,根据气体的击穿电压和放电电流来实现对单一气体和确定性混合气体的检测.为了提高检测混合气体的灵敏度,创新地在检测回路中引入随机共振发生装置,有效地提高了混合气体浓度检测的范围.实验中还分析了温度、湿度对传感器的影响,对该传感器的性能也作了评价.实验结果表明该传感器具有选择性好、体积小、响应时间快、灵敏度高、稳定性好,室温操作等优点,而且实现方便,操作简单,有较大的实用价值.     

纳米碳管气体放电气敏传感器中随机共振现象的研究

在对某些非线性动力学系统中,存在着随机共振现象,它不是通过消除噪声而是利用噪声来达到检测微弱信号的目的,随机共振是非线性动力系统中的普遍现象,它向人们展示了噪声在非线性体系中的积极作用.本文对纳米碳管气体放电气敏传感器中的随机共振现象进行了研究,利用纳米碳管电极作为气敏传感器阳极,在以空气为目标气体的传感器检测系统中观察到二重随机共振现象.提取放电周期脉冲信号,利用高斯白噪声调制放电周期脉冲信号,输出信噪比的仿真结果与实际观察到的二重随机共振现象一致.     

碳纳米管及其修饰物对挥发性有机物气敏性的研究

通过化学气相沉积(CVD)方法合成单壁碳纳米管(SWCNTs)和多壁碳纳米管(MWCNTs),并经过硝酸酸化预处理.在缩合剂N,N‘-二环己基碳化二亚胺(DCC)作用下,多壁碳纳米管经过乙二胺、十二胺和联苯胺的修饰生产新的纳米颗粒.将五种材料的悬浮液喷涂于Al2O3基底的金叉指电极上,构成气敏传感器,以甲醛、苯、甲苯、二甲苯作为测试气体,通过电化学分析仪测试他们在不同气体种类和浓度下的导电率.实验表面传感器在常温下具有较高的灵敏度和重复性,传感器之间有一定的选择性差异,可以构成传感器阵列,应用于具有复杂组分的挥发性有机气体定性和定量检测中.     

一维纳米材料在气体传感器中的应用

评述了目前一维纳米材料在气体传感器中的应用进展.包括单壁碳纳米管、多壁碳纳米管、单根金属及金属氧化物纳米带或纳米线制作的传感器,这些传感器能在室温下检测,具有灵敏度高、漂移小的优点,但由于制作成本高昂、检测条件苛刻,离实用还很远.将氧化物一维纳米材料用于制作旁热式气敏元件,在保持其高灵敏度的同时提高稳定性,有助于解决旁热式气敏元件实用中存在的稳定性差的问题,将成为目前实用化研究的一个热点.     

催化裂解简单合成离散的短纳米碳管

研究了一种简单催化裂解生长离散纳米碳管技术.不需要使用基底,于700℃,直接催化裂解Fe(NO3)3·9H2O和无水乙醇的混合溶液,反应30分钟,合成了长度较短的纳米碳管.需要指出的是,该研究与已有的催化裂解无水乙醇生长纳米碳管的区别在于:实验设备简单,工艺参数易于实现,反应温度较低,时间较短,碳源和催化剂间的反应在均相中发生.所得产物的扫描电镜、透射电镜表征显示,合成的纳米碳管呈开口状,相互缠绕程度较小,离散度较大.拉曼光谱检测表明产物为单壁纳米碳管和多壁纳米碳管混合物.文章还对纳米碳管的生长过程进行了探讨.     

超细MgFe_2O_4复合氧化物的气敏性能研究

以FeSO4·7H2O和MgCl2·6H2O为材料,用新型化学共沉淀法制备了纳米尺寸的复合金属氧化物MgFe2O4粉体。将样品做成厚膜型气敏元件,测定了其对乙醇、甲醛、丙酮、甲苯、苯氨气、石油醚等还原(可燃)性气体的气敏特性。测试显示:700℃下,热处理1h,所得纳米微粉制作的元件在300℃工作温度下对丙酮有较高灵敏度和良好的选择性,并对气敏机理给予了解释。     

NiFe2O4纳米材料的气敏性能研究

以FeSO4·7H2O和NiCl2*6H2O为原料,通过新型化学共沉淀法制备了纳米尺寸的NiFe2O4粉体,利用XRD、TEM等手段研究了其结构特性.NiFe2O4是一种新型的P型半导体气敏材料.以NiFe2O4纳米粉体为原料制备了烧结型旁热式气敏元件,该元件对甲苯具有较高的灵敏度和好的选择性,并对气敏机理给予了解释.     

Surface acoustic wave gas sensors based on polyisobutylene and carbon nanotube composites

Surface acoustic wave (SAW) gas sensors based on polyisobutylene (PIB) and composites (PIB and carbon nanotubes) as sensitive layers were investigated for the detection of octane and toluene (volatile organic compounds) and other atmospheric pollutants (H₂, CO, NO₂ and NH₃) at room temperature. In order to study the effect of nanotubes in the response of SAW sensors, several composites based on PIB with different percentages of multiwalled carbon nanotubes (MWNTs) were tested and compared to the response obtained from PIB SAW sensors. Sensors exhibit high responses and selectivity to volatile organic compounds (VOCs) with fast response and recovery times as well as good repeatability and reproducibility. Experimental results show as small percentages of nanotubes improve the response to octane.     

吸附甘氨酸对多壁碳纳米管电性能的影响

以磁控贱射的方法在玻璃基底上制作叉指银电极,用丝网印刷技术制备碳纳米管膜。室温下测试吸附甘氨酸前后碳纳米管膜伏安特性和电阻率的变化,发现吸附了甘氨酸后碳纳米管的导电能力增加,且增加的幅度与甘氨酸的浓度有关。实验结果预示:碳纳米管是一种良好的室温下检测甘氨酸的敏感材料。对碳纳米管吸附甘氨酸前后电性能的变化机理进行了初步的探讨。     

Electronic chip based on self-oriented carbon nanotube microelectrode array to enhance the sensitivity of indoor air pollutants capacitive detection

Highly sensitive capacitive detection is reported for indoor air pollutants, e.g. formaldehyde, toluene, and ammonia gas, at room temperature using an electronic chip with self-oriented carbon nanotube microelectrode array. A remarkable capacitive response is observed owing to the dense entanglement of CNTs and the highly porous 3D structured CNT network on the surface of gold electrode. Such kind of nanotubes can be considered as extended and oriented electrodes. As compared with the effect of spray-casting MWCNTs, the relative capacitance change of the above-mentioned electronic chip is found to increase from 1.8 to 70 by taking ammonia as an example. A model is proposed to explain qualitatively the sensing mechanism of electronic chip.     

聚苯胺-多壁碳纳米管薄膜SAW NO2传感器

将聚苯胺-多壁碳纳米管聚合物沉积于声表面波(SAW)气体传感器的敏感区,形成敏感薄膜,实现了室温下对不同体积分数NO2的检测.研究表明:这种传感器具有很高的敏感性,良好的重复性和低体积分数检测极限.同时,单一聚苯胺薄膜也做了对比测量,实验结果表明:聚苯胺-多壁碳纳米管聚合物敏感膜比单一聚苯胺薄膜具有更高的敏感性和更短的...     

La0.5Sr0.5CoO3−δ nanotubes sensor for room temperature detection of ammonia

La_0.5Sr_0.5CoO_3−δ (LSCO) nanotubes were synthesized by using a porous anodic aluminum oxide (AAO) template from a sol–gel solution. Based on the achievement of synthesis of LSCO nanotubes, a nanotube gas sensor was fabricated with microelectromechanical system technology and its NH₃ sensing characteristics were investigated. Capacitance of LSCO nanotubes was changed by two orders of magnitude within several seconds of exposure to NH₃ molecules at room temperature. The detection limit of the LSCO nanotube sensor was several ppm, and the typical response and recovery time of the sensor at room temperature was only several seconds. Our results demonstrate the potential application of LSCO nanotubes for fabricating a highly sensitive and fast response gas sensor.     

Characterization of layer-by-layer nano self-assembled carbon nanotube/polymer film sensor for ethanol gas sensing properties

This paper reported a multi-wall carbon nanotubes (MWNTs)/polymer film-based sensor for ethanol gas detection. The film sensor was fabricated using layer-by-layer self-assembly method on the substrate with interdigital electrodes structure. The surface morphology of the self-assembled membranes shows a high strength, dense and random network structures, and the electrical properties of MWNTs/polymer film sensor were investigated. Its ethanol gas-sensing properties with varying gas concentration are characterized at room temperature. The experiment results shown that carboxylic groups attached on the MWNTs surface and the expansion of polyelectrolyte interlayer lead to a prompt response and sensitive resistance change when the sensor exposed to ethanol gas, indicating the unique advantages of layer-by-layer self-assembly of MWNTs/polymer film sensors in prospective application.     

Microstructure control of TiO2 nanotubular films for improved VOC sensing

Porous gas sensing films composed of TiO₂ nanotubes were fabricated for the detection of volatile organic compounds (VOCs), such as alcohol and toluene. In order to control the microstructure of TiO₂ nanotubular films, ball-milling treatments were used to shorten the length of TiO₂ nanotubes and to improve the particle packing density of the films without destroying their tubular morphology and crystal structure. The ball-milling treatment successfully modified the porosity of the gas sensing films by inducing more intimate contacts between nanotubes, as confirmed by scanning electron microscopy (SEM) and mercury porosimetry. The sensor using nanotubes after the ball-milling treatment for 3 h exhibited an improved sensor response and selectivity to toluene (50 ppm) at the operating temperature of 500 °C. However, an extensive ball-milling treatment did not enhance the original sensor response, probably owing to a decrease in the porosity of the film. The results obtained indicated the importance of the microstructure control of sensing layers in terms of particle packing density and porosity for detecting large sized organic gas molecules.     

基于MWCNTs的气敏测试纸

介绍了一种简单、可直接在纸上制作的气体传感测试纸.由多壁碳纳米管(MWCNTs)在纸上摩擦,粘附的MWCNTs即为传感器的敏感层.采用相同方法分别在不同的纸张上制作传感器,并对气敏性能进行了比较,结果表明:滤纸的多孔性和粗糙的表面,可以促使其上的敏感层吸附和释放气体分子,使气体传感器在室温条件下完全恢复.传感器具有良好的重复性和稳定性.气体传感测试纸可以进一步用于挥发性有机气体(VOCs)的检测开发.     

Oxygen functionalisation of MWNT and their use as gas sensitive thick-film layers

Multi-wall carbon nanotubes (MWNT) were functionalised in an oxygen-based atmosphere by an inductively coupled RF-plasma at 13.56 MHz. X-ray photoelectron spectroscopy analysis showed that the chemical composition of the nanotube surface depends on the plasma conditions used. The MWNT were then deposited onto microhotplate gas sensor substrates by the drop coating method. A well-adhered thick-film of carbon nanotubes mesh (∼17 μm) was obtained after annealing in air. The influence of the different plasma conditions on the responsiveness of gas sensors fabricated with the functionalised MWNT was studied. The gas sensing properties were investigated both experimentally and theoretically for NO₂, and NH₃ at room temperature.