發(fā)布時(shí)間：2018-05-21 05:20

  本文選題：力控靜電紡絲 + 水熱法��； 參考：《華中科技大學(xué)》2016年博士論文

【摘要】：ZnO納米材料是最有前景的氣體傳感器功能材料,實(shí)現(xiàn)ZnO氣體傳感器的多功能一體化是氣體傳感器發(fā)展的必然趨勢(shì),但電子鼻或氣體傳感器陣列具有電路復(fù)雜、器件性能易受影響、故障率高、體積較大等缺陷。以可控的方式來(lái)實(shí)現(xiàn)ZnO氣敏功能材料的大面積圖案化不但能解決上述問(wèn)題,簡(jiǎn)化電路,還能優(yōu)化ZnO氣體傳感器的氣敏性能,推進(jìn)氣敏器件的多功能一體化發(fā)展。已有的圖案化工藝有壓印法、沉積法、刻蝕法、傳統(tǒng)噴墨打印等,它們大都要求高溫、高真空,過(guò)程復(fù)雜,分辨率低,需要掩�；蚰＞�,設(shè)備比較昂貴,違背了氣體傳感器低成本、普適性的要求。本學(xué)位論文基于力控靜電紡絲法和水熱生長(zhǎng)法制備了圖案化分級(jí)結(jié)構(gòu)ZnO納米棒陣列氣敏功能材料,并進(jìn)行性能表征和優(yōu)化,主要研究工作和創(chuàng)新如下：本文通過(guò)系統(tǒng)實(shí)驗(yàn)深入研究了靜電紡絲過(guò)程中溶液參數(shù)和工藝參數(shù)對(duì)靜電紡絲工藝的影響,包括分子量、溶液濃度、工藝電壓、電極間距、噴嘴內(nèi)徑等,得到了這些參數(shù)對(duì)纖維直徑和形貌的影響規(guī)律,提高了工藝的可控性。結(jié)合傳統(tǒng)靜電紡絲和近場(chǎng)靜電紡絲的優(yōu)點(diǎn),提出力控靜電紡絲工藝MES。MES通過(guò)減小噴嘴與基板的距離以改善纖維定位,能直寫(xiě)制備高精度纖維圖案,電場(chǎng)的作用是產(chǎn)生泰勒錐并拉出射流。機(jī)械拉力是由運(yùn)動(dòng)平臺(tái)產(chǎn)生的,其大小是由運(yùn)動(dòng)速度調(diào)控的,進(jìn)而用于輔助射流定位和控制沉積圖案的纖維直徑。采用力控靜電紡絲輔助水熱合成法(MES-CHSM)以可控的、無(wú)掩模的方式成功制備了圖案化分級(jí)結(jié)構(gòu)ZnO納米棒陣列(ZnO-NAs)。制備過(guò)程分為兩步：首先,用力控靜電紡絲法將ZnO前驅(qū)體種子溶液在基板上定位直寫(xiě)成纖維圖案,退火后生成ZnO的種子層;其次,采用水熱法生長(zhǎng)成ZnO納米棒陣列。ZnO納米棒的直徑、間隔、朝向和分布等都可以通過(guò)改變生長(zhǎng)時(shí)間、生長(zhǎng)溶液濃度、前驅(qū)體濃度以及MES工藝中圖案纖維的間距進(jìn)行調(diào)整。ZnO-NAs可以用作氣體傳感器的功能材料,其形貌和分布都會(huì)對(duì)氣敏性能有很大的影響,形貌和分布又是由MES-CHSM的工藝參數(shù)決定的。無(wú)論是在空氣還是在N02氛圍中,ZnO-NAs與叉指電極間都表現(xiàn)為優(yōu)異的歐姆接觸。ZnO-NAs氣體傳感器有高靈敏度和可重復(fù)性,其對(duì)NO2的靈敏度與工作溫度有關(guān),在200℃到225℃之間的工作溫度下,ZnO-NAs氣體傳感器具有最高的靈敏度。對(duì)于通過(guò)不同的工藝參數(shù)制備的樣品,靈敏度隨NO2濃度增加表現(xiàn)出兩種規(guī)律：近似線性增加關(guān)系和趨于飽和關(guān)系。選擇最佳的工藝參數(shù)可以推遲飽和區(qū)的發(fā)生,擴(kuò)大測(cè)量范圍。利用MES-CHSM和光還原法制備了分級(jí)結(jié)構(gòu)Ag/ZnO納米棒陣列,ZnO納米棒表面的Ag+被成功光還原為Ag納米顆粒。Ag納米顆粒改善了ZnO-NAs對(duì)NO2的氣敏性能,Ag/ZnO納米棒陣列的氣敏性能與光還原時(shí)間有關(guān),用30分鐘時(shí)間光還原的樣品具有最佳的靈敏度,并就Ag納米顆粒對(duì)氣敏性能的優(yōu)化機(jī)理進(jìn)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，

本文編號(hào)：1917904