利用纳米ZnO粉制备厚膜气敏传感器的研究

以ZnO纳米粉(平均粒径30nm)为原料,利用水热热压方法制备了ZnO多孔纳米固体,同时用通常的水热法对ZnO纳米粉进行了预处理(预处理ZnO纳米粉)。然后,分别以ZnO多孔纳米固体和预处理ZnO纳米粉为原料,制备了厚膜气敏传感器。本征电阻的测试结果表明,这两种厚膜气敏传感器的本征电阻比用未经处理的ZnO纳米粉(以下简称“原料ZnO纳米粉”)制备的厚膜气敏传感器大大降低并很快达到稳定状态。有效地改善了器件工作的稳定性。结合对三种传感器的显微结构分析,对出现上述差异的原因进行了讨论。     

层状多孔ZnO厚膜的制备及其气敏性能研究

由片状材料的定向自组装得到的层状结构可以使膜具有良好的取向性和特殊的物理化学性能。通过对ZnSO4.7H2O在150℃进行水热反应合成出高径厚比的碱式硫酸锌薄片,然后将这种大面积的薄片组装成一定厚度的自持膜并进一步热处理成具有多孔结构的层状ZnO厚膜。通过对600℃、700℃和800℃热处理得到的材料进行XRD及SEM分析,研究了其成分及多孔结构的产生过程,并结合气敏测试结果证明由烧结温度所带来的多孔结构的变化确实会对其气敏性能造成一定的影响。对不同气体进行的气敏性能测试表明,这种层状多孔ZnO结构是一种理想的气敏传感材料,特别适合用于检测H2S气体。     

掺杂Fe2 O3对ZnO多孔纳米固体厚膜气敏传感器性能的影响

以ZnO纳米粉(平均粒径30 nm)和Fe2O3,纳米粉(平均粒径90 nm)为原料,利用传统的厚膜气敏传感器制备工艺,制备了纯ZnO多孔纳米固体厚膜气敏传感器和掺杂Fe2O3(掺杂量为1wt%,2wt%和5wt%)的ZnO厚膜气敏传感器.分别测试了这四种厚膜气敏传感器的本征电阻(传感器在空气中的电阻值)及其对乙醇,汽油,丙酮,对二甲苯,氢气,甲烷和CO敏感特性.结果表明:当工作温度在较低时,Fe2O13,的掺杂可明显降低ZnO多孔纳米固体厚膜气敏传感器的本征电阻,并提高其工作稳定性,而适量Fe2O3的掺杂可以提高ZnO多孔纳米固体厚膜气敏传感器对乙醇蒸气和汽油的灵敏度.结合对传感器厚膜的显微结构分析结果,我们对出现上述差异的原因进行了初步讨论.     

纳米ZnO气敏传感器研究进展

半导体金属氧化物气敏传感器被广泛应用于有毒性气体、可燃性气体等的检测.ZnO是一种重要的半导体气敏材料,特别是纳米ZnO,由于其粒子尺寸小,比表面积大,成为被广泛研究的气敏响应材料之一.简要介绍了纳米ZnO气敏传感器的气敏机理、主要特性,综述了通过新型纳米形貌、结构制备以及元素掺杂改性提升纳米ZnO气敏性能等方面的研究进展,并进一步指出了纳米ZnO气敏传感器研究中存在的问题和未来的研究方向.     

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.     

Cu2+掺杂ZnO纳米棒的制备及气敏性能研究

通过溶剂热法(无水乙醇)制备了Cu2+(0～6mol%)掺杂ZnO纳米棒粉体,采用X射线衍射仪和扫描电镜对掺杂ZnO纳米粉体的晶体结构和微观形貌进行了表征.研究了Cu2+掺杂比例、溶剂热反应温度及时间对材料气敏性能的影响;考察ZnO(120℃,10h)和3mol%Cu2+掺杂ZnO(120℃,10h)粉体对应元件对甲醛、乙酸、甲苯、乙醇、丙酮、三甲胺等六种气体的气敏性能.结果表明:通过溶剂热法制备的ZnO粉体为纳米棒状结构,棒长度和直径随Cu2+掺杂比例不同发生变化;3mol%Cu2+掺杂ZnO(120℃,10h)样品对应元件对低浓度乙醇有很好的选择性,在395℃工作温度下对1×10–3乙醇的灵敏度为380.5,响应和脱附时间分别为5 s和40 s,对1×10–6乙醇的灵敏度可达4.2.     

单晶多孔ZnO制备及对室内空气污染物的气敏性能的研究

通过使用对液相法合成的前驱体进行煅烧的方法成功的制备了具有单晶多孔结构的Zn O纳米片。通过X射线衍射仪(XRD)、环境扫描电子显微镜(FESEM)、高分辨透射电子显微镜(TEM)对单晶多孔Zn O纳米片进行了结构以及形貌的表征和分析。以其为敏感膜,制作气体传感器,对室内空气污染物,包括苯和甲醛,进行检测。结果显示单晶多孔Zn O纳米片对苯和甲醛都有着良好的响应,且响应和恢复时间都非常迅速。对敏感机理以及材料的结构对响应时间的影响也进行了较深入的探讨。     

纳米ZnO的固相合成及其气敏特性

以草酸为原料,与醋酸锌进行固相反应制得前驱化合物,进而热分解得到气敏材料氧化锌。将稀土元素中的镧和钕的氧化物以固相及液相两种合成方法添加到ＺｎＯ气敏材料中,并对材料的粒径、气敏性质进行了测定和表征．实验结果表明,用这种方法制备的氧化锌在低的工作温度下对乙醇气体的灵敏度较高,而且选择性较好,具有一定的应用前景．     

掺杂Al2O3纳米粉对ZnO厚膜气敏传感器性能的影响

以ZnO纳米粉(平均粒径30 nm)和Al2O3纳米粉(平均粒径5 nm)为原料,利用传统的厚膜气敏传感器制备工艺制备了纯ZnO厚膜气敏传感器和掺杂Al2O3(掺杂量为2wt%和5wt%)的ZnO厚膜气敏传感器.对这三种厚膜传感器的本征电阻及对乙醇蒸汽的敏感特性进行了测试.结果表明:掺杂少量Al2O3纳米粉可明显降低ZnO气敏传感器的本征电阻,改善传感器的烧结性能,同时还可降低其最佳工作温度,提高器件对乙醇的灵敏度.结合厚膜气敏传感器的显微结构分析结果,对出现上述差异的原因进行了讨论.     

电弧等离子体制备纳米ZnO的气敏特性

用Ｈ２＋Ａｒ电弧等离子体法制成纳米ＺｎＯ，ＺｎＯ－Ｆｅ，研究了其气敏特征及机理，结果表明：与其它制备方法相比，该方法制成的纳米ＺｎＯ气敏元件在没有贵金属掺杂的情况具有较高的灵敏度，工作温度为２００℃￣２５０℃，为常规元件的一半，纳米ＺｎＯ－Ｆｅ－Ｐｄ对液化石油气（ＬＰＧ）的选择性比纳米ＺｎＯ好，具有快速响应（〈１５ｓ）的恢复特性，能稳定地连续工作７０ｈ以上，可制作低功耗ＬＰＧ气敏元件。     

Preparation and characterization of ZrO2 porous nanosolid and its composite fluorescent materials

ZrO₂ porous nanosolid has been successfully prepared by a novel hydrothermal hot-press (HHP) method, using ZrO₂ nanoparticles as the starting material. Furthermore, a kind of O, O-donating chelating regent, morin was assembled into the pores of ZrO₂ porous nanosolids, and a morin/ZrO₂ porous nanocomposite was obtained. Because of the interaction between morin molecules and the surface of ZrO₂ porous nanosolid, a blue-shift of the photoluminescence (PL) peak was observed in ZrO₂/morin nanocomposite by comparing with that of morin.     

Preparation and characterization of ZnO porous plates

This article presents two main steps to prepare zinc oxide porous plates. Firstly, the precursor zinc hydroxide chloride hydrate (Zn₅(OH)₈Cl₂·H₂O) was synthesized by ZnCl₂ and ethylenediamine ((CH₂NH₂)₂). Secondly, the precursor was put into a furnace and annealed at 500 °C. And then the zinc oxide porous plates were successfully obtained. The crystal structures and the microstructures of the precursor and the final product were analyzed and compared by XRD, SEM and TEM. The specific surface area and gas adsorption isotherm of the final product were tested by Brunauer-Emmett-Teller equipment.     

The potential of porous silicon gas sensors

Recent developments in porous silicon gas sensors have been reviewed. Monitored species detection levels, and the mechanisms of sensing for different sensor designs are also discussed. Porous silicon surface modification methods have been employed for detecting different gas molecules; H₂O, ethanol, methanol, isopropanol, CO_x, NO_x, NH₃, O₂, H₂, HCl, SO₂, H₂S and PH₃.     

Monodisperse hematite porous nanospheres: synthesis, characterization, and applications for gas sensors

Monodisperse α-Fe(2)O(3) porous nanospheres with uniform shape and size have been synthesized via a facile template-free route. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and Raman spectroscopy were employed to characterize the product, showing the high quality of the as-prepared α-Fe(2)O(3) porous nanospheres. Furthermore, the α-Fe(2)O(3) porous nanospheres can selectively detect ethanol, formaldehyde and acetic acid, with a rapid response and high sensitivity, from a series of flammable and toxic/corrosive gases, indicating their potential applications for high sensitivity gas sensors.     

Chemical deposition of ZnO films for gas sensors

Zinc oxide (ZnO) thin films were prepared following a chemical, deposition technique using a sodium zincate bath. Structural characterizations by scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicate the formation of ZnO film with a preferred c-axis orientation. The electrical conductance of the ZnO films became stable and reproducible in the 300–500 K temperature range with two activation energy barrier values of 0.3 eV and 0.8 eV in the low temperature (300–420 K) and high temperature (430–500 K) ranges, respectively. The ZnO films prepared by this method are highly resistive, indicating the presence of a large density of oxygen adsorbed acceptor-like trap states (O ₂ ^- , O_-, etc.). Palladium sensitized ZnO films were exposed to hydrogen (H₂) with air as a carrier gas at different operating temperatures ranging between 150–375°C and the response is evaluated.     

Preparation of porous boehmite nanosolid and its composite fluorescent materials by a novel hydrothermal hot-press method

Boehmite (AlO(OH)) porous nanosolid has been successfully prepared by a novel hydrothermal hot-press (HHP) method, using Al₂O₃ nanoparticles as the starting material. Furthermore, a new organic fluorescent material (E,E)-4-{2-[P′-(N,N-di-n-butylamino)stilben-p-yl]vinyl}pyridine (DBASVP) was assembled into the pores of the boehmite porous nanosolid, thus a DBASVP/boehmite porous nanocomposite was obtained. Because of the interaction between DBASVP molecules and the surface of boehmite porous nanosolid, a red-shift of the fluorescent peak was observed in boehmite/DBASVP composite by comparing with that of DBASVP.     

Preparation and characterization of bowl-like porous ZnO film by electrodeposition using two-dimensional photonic crystal template

A rapid and low-cost method combining electrodeposition with two-dimensional (2D) photonic crystal template technique to prepare large scale bowl-like porous ZnO films is described. The 2D photonic crystal templates were fabricated by self-assembly of monodispersed polystyrene (PS) microspheres on indium-tin-oxide coated glass substrates using spinning coating method. The interstitial spaces among the spheres of the templates were filled with ZnO via electrodeposition from an aqueous solution containing 0.02 M zinc nitrate as electrolyte under a constant potential of ?1.0 V at 65 °C for 10 min. After removal of the PS photonic crystal template, bowl-like porous ZnO film was obtained. The entire process can be accomplished within 30 min. Scanning electron microscopic images showed good homogeneity in morphology, X-ray diffraction spectra demonstrated the wurtzite structure of the obtained ZnO film, and transmission electron microscopy indicated the single-crystallinity of the ZnO. Ultraviolet–visible (UV–vis) spectrophotometer was used to detect the absorption in UV–vis region of the PS template, opal ZnO-PS composite and inverse opal ZnO respectively. Two strong emission bands at 400 and 550 nm were displayed in photoluminescence spectrum.     

负载活性炭硅藻土多孔陶瓷的制备和过滤性能研究

采用注浆成型技术制备了负载活性炭的硅藻土多孔陶瓷,研究烧结温度对其孔径、孔隙率、强度和晶相的影响,并测定其细菌过滤性能。研究发现,经1000℃烧成的产品,硅藻土保持原有的微孔结构,孔隙率最高(67%),强度较好(5.81MPa),而且对大肠杆菌截留效果好,滤液中未检测出大肠杆菌,可满足国家饮用水标准的要求。     

Sensitivity-tuned CO gas sensors with tailored Ga-doping in ZnO nanowires

Sensitivity-customization of zinc oxide (ZnO) nanowire (NW) gas sensors has been demonstrated by controlling Ga-doping, thereby tuning the resistance of the NWs. Both un-doped and 5 weight% Ga-doped ZnO (GZO) NWs are synthesized for the highly sensitive sensing within a narrow detection window and a less sensitive one within an expanded window, respectively. We have employed hot-walled pulsed laser deposition (HW-PLD) for the NW synthesis. With CO gas injection, the resistance reduction of NWs is detected and analyzed in a self-designed gas chamber that guarantees the precise control of gas flow and, gas concentration, as well as temperature. NW sensitivity is proportional to the sensing temperature and inversely proportional to the doping concentration resulting in widening the sensing window up to 230 times by the 5 wt.% Ga-doping.