微液滴注法制备掺杂ZnO传感器及其气敏性能研究

采用自制ZnO颗粒,通过丝网印刷制备了ZnO平板型厚膜气体传感器,使用微液滴注的方法对ZnO传感器进行Mg,Mn,Sn,Pd掺杂,测量了传感器对乙醇、丙酮、苯、乙酸的气敏性能。结果表明:微滴掺杂能有效提高传感器敏感性和选择性,其中,Mg掺杂传感器对乙醇和丙酮具有最大响应值,同时Mn掺杂传感器对乙酸表现出了较好的选择性。     

掺杂对ZnO气敏性能的影响研究

ZnO是最早发现的金属氧化物气敏材料,对其掺杂一直是研究的一个热点.采用机械球磨法制备了22种不同掺杂的纳米ZnO气敏材料,通过乙醇、丙酮、苯的测试,系统对比了掺杂元素的化学性质,如离子半径、化合价、元素周期等对ZnO气敏性能的影响.掺杂元素的离子半径为0.072～0.088 nm时,传感器对被测气体的响应比掺杂其他离子半径的高.不同周期掺杂元素对ZnO纳米气体传感器的选择性有一定的影响.     

表面改性四针状纳米ZnO结构与气敏性能研究

将4种质量分数(5%,10%,20%,30%)的Co(CH3COO)24H2O混合到四针状纳米ZnO原料里,采用超声化学浸泡法制备出表面改性四针状纳米ZnO颗粒。通过XRD和TEM分析了表面改性四针状纳米ZnO结构的物相和形貌特征。随着Co(CH3COO)24H2O质量分数增大,Co3O4相明显出现,Co3O4相沉积在ZnO表面上。研究表明:以表面改性四针状纳米ZnO粉末为原料制备的厚膜气敏元件,与纯ZnO气敏元件相比,Co(CH3COO)24H2O质量分数为5%的气敏元件对酒精和甲醇有较高的灵敏度,并讨论了表面改性对气敏性能的影响。     

掺入SiO2纳米颗粒对厚膜ZnO气敏传感器气敏性能的影响

利用丝网印刷技术,制备出掺入SiO2和未掺入SiO2的ZnO厚膜气敏传感器,测试对甲醇和乙醇的气敏性能,并用场发射扫描电子显微镜(FESEM)来分析表征气敏膜的微观形貌。结果表明SiO2的掺人有效地抑制了ZnO晶粒的长大。在工作温度为400～450℃时,SiO2的掺入显著提高了ZnO厚膜气敏传感器对甲醇和乙醇的敏感度,...     

氧化锌基乙醇气体传感器研制及特性研究

利用水热法合成了不同形貌的ZnO基纳米结构气敏材料,利用X射线衍射仪(XRD)和扫描电子显微镜 (SEM)对其进行了结构表征和分析。制备成旁热式气体传感器,测试了其对乙醇(C2H5OH)的气敏特性。实验结果表明：基于ZnO纳米花制作出的传感器比纳米球状传感器对C2H5OH具有更高的灵敏度,在200oC下对50ppm的C2H5OH灵敏度为34.7,是球状ZnO基传感器的1.7倍;两种ZnO基传感器对C2H5OH均表现出较好的重复性,在最佳工作温度下对C2H5OH的响应恢复时间均在15秒以内;最后对ZnO基C2H5OH气体传感器的气敏机理进行了讨论。     

外磁场诱导Ni-ZnO型甲醛传感器气敏性研究

结合NiO和四针状纳米ZnO的优点,提出了利用平行和垂直气敏膜的磁场诱导Ni纳米颗粒在四针状纳米ZnO气敏膜中的分布来制备甲醛气体传感器的方法.介绍了制备方法,分析了对甲醛的敏感性及其气敏性机理,测试了在不同使用方式中的稳定性.实验结果表明:平行于厚膜表面的磁诱导5%的Ni掺杂ZnO厚膜具有较好的稳定性,同时,对甲醛具有最佳的气敏性和检测的重复性,以其作为甲醛气体探测器具有很好的前景.     

溅射Au对SnO_2/Fe_2O_3薄膜气敏特性的影响

通过直流溅射Au对PCVD方法制备的SnO2/Fe2O3双层薄膜的SnO2表面进行了修饰,并对修饰后的Au SnO2/Fe2O3薄膜的气敏特性进行了观测。结果表明,Au的催化作用使Au SnO2/Fe2O3薄膜气敏器件对CO,H2,C2H5OH等气体的灵敏度增大2～3倍,相应于最大灵敏度的工作温度均降低约60℃。这显示直流溅射Au是改善SnO2/Fe2O3双层薄膜气敏性能的一种有效手段。     

基于高通量筛选的高性能NO_x气敏材料研究

以SnO_2,BaTiO_3,ZnO为原材料设计一组材料体系,利用气敏膜并行合成仪并行制备45种气敏膜,通过高通量气敏性能无人测试仪表征气敏性能,筛选出对氮氧化物(NO_x)气体敏感性、选择性较好的材料。通过对NO,NO_2,苯、甲醛、CO、乙醇气体的气敏性能测试,发现当SnO_2和BaTiO_3按摩尔比6∶2复合时,在200℃时对500×10~(-9)NO,500×10~(-9)NO_2响应值分别有142,113.4,且具有较好的选择性。最后,对SnO_2—BaTiO_3复合材料如何提升传感器性能进行了讨论。     

氧化物半导体甲烷敏感元件研究进展

介绍了氧化物半导体甲烷气体敏感元件的工作机理,论述了改善氧化物半导体甲烷气敏传感器性能的几种途径.采用加入催化剂、控制材料的微细结构、利用新制备工艺和表面修饰等新方法、新技术可提高氧化物半导体甲烷气敏元件的灵敏度、选择性、响应和恢复特性、稳定性.     

紫光激发提高ZnO基半导体气敏传感器的敏感性能

以激光-感应复合加热法制备的纳米ZnO粉末为气敏基料,制作厚膜型的管状气敏元件,采用紫光(波长为370～395nm)激发,对无水乙醇进行了静态配气法的气敏性能测试.结果表明在紫光激发下,ZnO基半导体气敏传感器在较低的工作温度条件下对无水乙醇具有较好的气敏性能,而且随着紫光光强的增大,气敏性能提高.     

LPG sensing properties of Pd-sensitized vertically aligned ZnO nanorods

One-dimensional (1-D) vertically aligned ZnO nanorods are synthesized on glass substrate through a simple chemical route and their liquefied petroleum gas (LPG) sensing properties are studied. The morphology and structure of vertically aligned ZnO nanorods has been characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The LPG sensing properties of the vertically aligned ZnO nanorods are improved significantly after palladium (Pd) sensitization. The unsensitized vertically aligned ZnO nanorods exhibited the maximum response of 37% at 573 K upon exposure to 2600 ppm LPG, which improved to 60% at operating temperature of 498 K after the Pd sensitization. The Pd-sensitized vertically aligned ZnO nanorods showed more selectivity towards LPG as compared to CO₂. Our results demonstrate that the chemically grown vertically aligned ZnO nanorods along with Pd sensitization are promising material for the fabrication of cost effective and high performance gas sensors.     

Enhanced sensing characteristics in MEMS-based formaldehyde gas sensors

This paper presents a novel micro fabrication for formaldehyde gas sensors to enhance sensitivity and detection resolution capabilities. Therefore, two different types of fabrication sequences of gas sensors were considered, different positions of micro heaters and sensing layers to compare the effects of different areas of the sensing layers contact with the surrounding gas. The MEMS-based formaldehyde gas sensor consists of a quartz substrate, a thin-film NiO/Al₂O₃ sensing layer, an integrated Pt micro-hotplate, and Pt inter-digitized electrodes (IDEs) to measure the resistance variation of sensing layers caused by formaldehyde oxidation at the oxide surface. This abstract offers comparisons of the characteristics of sensors in different areas of the sensing layers contacting the surrounding gas as well as those to decrease the thickness of the sensing layer and deposits of the sensing layer using co-sputtering technology with NiO/Al₂O₃ to improve the sensitivity limits of the sensors. The experimental data indicated that increasing the area of the sensing layer that contacts with the surrounding gas and decreasing the thickness of the sensing layer in the sputtering process and then co-sputtered NiO/Al₂O₃ sensing layers, significantly enhanced the sensing characteristics of the developed formaldehyde sensor.     

Necked ZnO nanoparticle-based NO2 sensors with high and fast response

The NO₂ gas sensing characteristics of semiconductor type gas sensors with channels composed of necked ZnO nanoparticles (NPs) were investigated in this study. The heat treatment of the NPs at 400 °C led to their necking and coarsening. The response of the necked-NP-based sensors was as high as 100 when exposed to 0.2 ppm of NO₂ at 200 °C. As the concentration of NO₂ increased to 5 ppm, their response was enhanced to approximately 400. During the repeated injection of NO₂ gas with a concentration of 0.4 ppm, the sensors exhibited stable response characteristics. Furthermore, the 90% response and recovery times of the gas sensor were as fast as 13 and 10 s, respectively. These observations indicate that the non-agglomerated necking of the NPs induced by the heat treatment significantly enhances the gas sensing characteristics of the NP-based gas sensors.     

Y沸石改善SnO2气体传感器性能的研究

为了改善气体传感器的敏感性能,分别采用SnO2外涂Y沸石的涂覆法和Y沸石与SnO2混合法,用Y沸石对SnO2气体传感器进行改性.用X-射线衍射(XRD)、电子扫描显微镜(SEM)对混合法制备的Y沸石/SnO2复合材料的结构和表面进行了表征与分析.将这两类敏感元件进行了VOC气体的气敏测试.结果表明,与纯SnO2相比,Y沸石与SnO2直接混合的复合材料提高了对丙酮的响应值,而对其他气体响应值基本不变;涂覆法制备的气敏元件不仅提高对丙酮的响应值,而且减小了对乙醇的响应值,对乙醇起到一定抑制作用.初步分析了Y沸石对SnO2气敏特性改善的机理.     

氧化锌气体传感器的制备及甲烷检测特性研究

甲烷(CH4)是电力变压器油纸绝缘中溶解的主要故障特征气体,能有效反映运行变压器油纸绝缘故障.气体传感检测是油中气体在线监测、分析的关键.基于水热法,制备了氧化锌(ZnO)纳米片和纳米球气敏材料及传感元件,基于实验室搭建的微量气体检测平台测试了其对CH4的检测特性.研究表明:基于ZnO纳米片制作的气体传感器比纳米球传感器对CH4表现出更好的气敏性能,对50μL/L CH4的最佳工作温度降低了约60℃,同时对低浓度(1μL/L～20μL/L)CH4表现出较高的线性度和长期稳定性.本研究对研制高性能的ZnO基CH4气体传感器奠定了基础.     

High-performance liquefied petroleum gas sensing based on nanostructures of zinc oxide and zinc stannate

Toxic and combustible gas detection plays a major role in environmental air quality monitoring. Real-time monitoring of hazardous gases and signal of accidental leakages is of great importance owing to the concern for safety requirements in industries and household applications. A simple and economical method for the fabrication of highly sensitive zinc oxide (ZnO) nanorods based gas sensors for detecting low concentrations of Liquefied Petroleum Gas (LPG) was studied in this work. Platinum (Pt) nanoparticles were deposited on the sensing medium which acts as catalysts to improve the sensor performance. The change in electrical resistance of the metal oxide semiconductor for varying concentrations of LPG was measured. Maximum response of 59% was achieved for 9000 ppm LPG at 250 °C. Further to improve the sensing performance of the sensor towards LPG, surface modification of ZnO nanorods using zinc stannate (Zn₂SnO₄) microcubes was performed. High response of 63% was observed for 3000 ppm LPG at 250 °C. Significant improvement in response of the sensor with Zn₂SnO₄ microcubes on ZnO nanorods was observed when compared to sensor with ZnO nanorods.     

Vertically aligned ZnO nanorods and graphene hybrid architectures for high-sensitive flexible gas sensors

We present the fabrication and characterization of new type of flexible gas sensors, composed mainly of a bottom ZnO conductive layer on metal foil, vertically aligned ZnO nanorod channel, and graphene-based top conductive electrode. Multiple cycling tests demonstrated the ZnO nanorods (NRs) and graphene (Gr) hybrid architectures accommodated the flexural deformation without mechanical or electrical failure for bending radius below 0.8 cm under the repeated bending and releasing up to 100 times. In addition, the hybrid architectures fabricated on glass substrate showed good optical transmittance larger than ∼70% for visible light, indicating potential application in transparent devices. Furthermore, our gas sensors demonstrated the ppm level detection of ethanol gas vapor with the sensitivity (resistance in air/resistance in target gas) as high as ∼9 for 10 ppm ethanol.     

平面直热式气敏元件及其表面修饰

采用液相掺Sb的共沉淀方法制备低阻SnO2 纳米微粉 ,以其为敏感材料掺入Pt2wt%及Au5 .4at %的催化剂 ,在Si衬底上制作了平面直热式气敏元件。利用 2 %的Co(NO3 ) 3 溶液作为修饰液对元件进行表面修饰 ,可制得对NH3 具有较高灵敏度及选择性的敏感材料。