分级结构ZnO阵列的电流体直写制备及气敏性能研究

发布时间：2018-05-21 05:20

  本文选题：力控静电纺丝 + 水热法　； 参考：《华中科技大学》2016年博士论文

【摘要】：ZnO纳米材料是最有前景的气体传感器功能材料,实现ZnO气体传感器的多功能一体化是气体传感器发展的必然趋势,但电子鼻或气体传感器阵列具有电路复杂、器件性能易受影响、故障率高、体积较大等缺陷。以可控的方式来实现ZnO气敏功能材料的大面积图案化不但能解决上述问题,简化电路,还能优化ZnO气体传感器的气敏性能,推进气敏器件的多功能一体化发展。已有的图案化工艺有压印法、沉积法、刻蚀法、传统喷墨打印等,它们大都要求高温、高真空,过程复杂,分辨率低,需要掩模或模具,设备比较昂贵,违背了气体传感器低成本、普适性的要求。本学位论文基于力控静电纺丝法和水热生长法制备了图案化分级结构ZnO纳米棒阵列气敏功能材料,并进行性能表征和优化,主要研究工作和创新如下：本文通过系统实验深入研究了静电纺丝过程中溶液参数和工艺参数对静电纺丝工艺的影响,包括分子量、溶液浓度、工艺电压、电极间距、喷嘴内径等,得到了这些参数对纤维直径和形貌的影响规律,提高了工艺的可控性。结合传统静电纺丝和近场静电纺丝的优点,提出力控静电纺丝工艺MES。MES通过减小喷嘴与基板的距离以改善纤维定位,能直写制备高精度纤维图案,电场的作用是产生泰勒锥并拉出射流。机械拉力是由运动平台产生的,其大小是由运动速度调控的,进而用于辅助射流定位和控制沉积图案的纤维直径。采用力控静电纺丝辅助水热合成法(MES-CHSM)以可控的、无掩模的方式成功制备了图案化分级结构ZnO纳米棒阵列(ZnO-NAs)。制备过程分为两步：首先,用力控静电纺丝法将ZnO前驱体种子溶液在基板上定位直写成纤维图案,退火后生成ZnO的种子层;其次,采用水热法生长成ZnO纳米棒阵列。ZnO纳米棒的直径、间隔、朝向和分布等都可以通过改变生长时间、生长溶液浓度、前驱体浓度以及MES工艺中图案纤维的间距进行调整。ZnO-NAs可以用作气体传感器的功能材料,其形貌和分布都会对气敏性能有很大的影响,形貌和分布又是由MES-CHSM的工艺参数决定的。无论是在空气还是在N02氛围中,ZnO-NAs与叉指电极间都表现为优异的欧姆接触。ZnO-NAs气体传感器有高灵敏度和可重复性,其对NO2的灵敏度与工作温度有关,在200℃到225℃之间的工作温度下,ZnO-NAs气体传感器具有最高的灵敏度。对于通过不同的工艺参数制备的样品,灵敏度随NO2浓度增加表现出两种规律：近似线性增加关系和趋于饱和关系。选择最佳的工艺参数可以推迟饱和区的发生,扩大测量范围。利用MES-CHSM和光还原法制备了分级结构Ag/ZnO纳米棒阵列,ZnO纳米棒表面的Ag+被成功光还原为Ag纳米颗粒。Ag纳米颗粒改善了ZnO-NAs对NO2的气敏性能,Ag/ZnO纳米棒阵列的气敏性能与光还原时间有关,用30分钟时间光还原的样品具有最佳的灵敏度,并就Ag纳米颗粒对气敏性能的优化机理进行了分析。
[Abstract]:ZnO nanomaterials are the most promising functional materials for gas sensors. The multifunctional integration of ZnO gas sensors is an inevitable trend in the development of gas sensors, but electronic nose or gas sensor arrays have complex circuits. Device performance is easy to be affected, high failure rate, large size and other defects. The realization of large area patterning of ZnO gas sensing functional materials in a controllable way can not only solve the above problems, simplify the circuit, but also optimize the gas sensing performance of ZnO gas sensors, and promote the multifunctional integration of gas sensors. The existing patterning processes include imprint, deposition, etching, traditional inkjet printing and so on. Most of them require high temperature, high vacuum, complex process, low resolution, need mask or mould, and the equipment is expensive. Contrary to the gas sensor low cost, universal requirements. In this dissertation, the gas-sensing functional materials of patterned and graded ZnO nanorod arrays were prepared by electrospinning and hydrothermal growth, and their properties were characterized and optimized. The main research work and innovations are as follows: in this paper, the effects of solution parameters and process parameters on electrostatic spinning process, including molecular weight, solution concentration, process voltage, electrode spacing, were studied through systematic experiments. The influence of these parameters on the diameter and morphology of the fiber was obtained, and the controllability of the process was improved. Combined with the advantages of traditional electrostatic spinning and near-field electrostatic spinning, this paper puts forward that the force-controlled electrostatic spinning process (MES.MES) can improve fiber orientation by reducing the distance between nozzle and substrate, and can be directly written to prepare high-precision fiber patterns. The effect of an electric field is to produce a Taylor cone and pull out the jet. Mechanical pull is generated by moving platform and its size is regulated by moving velocity, which is used to assist the jet to locate and control the fiber diameter of the deposited pattern. The patterned ZnO nanorod arrays of ZnO nanorods were successfully prepared by force controlled electrospinning assisted hydrothermal synthesis (MES-CHSM) in a controllable and mask free manner. The preparation process is divided into two steps: firstly, the ZnO precursor seed solution is positioned on the substrate to form a fiber pattern by the force controlled electrostatic spinning method, and the seed layer of ZnO is formed after annealing. The diameter, spacing, orientation and distribution of ZnO nanorods were grown by hydrothermal method. The concentration of precursor and the spacing of pattern fibers in MES process can be adjusted. ZnO-NAs can be used as the functional material of gas sensor. Its morphology and distribution have great influence on the gas sensing performance, and the morphology and distribution are determined by the technological parameters of MES-CHSM. Both in air and in N02 atmosphere, the excellent ohmic contact. ZnO-NAs gas sensor has high sensitivity and repeatability, and its sensitivity to NO2 is related to the working temperature. The ZnO-NAs gas sensor has the highest sensitivity at operating temperature from 200 鈩，

本文编号：1917904