【摘要】：隨著生態(tài)環(huán)境的惡化,對(duì)環(huán)境進(jìn)行高效、實(shí)時(shí)監(jiān)控的迫切需要對(duì)氣體傳感器的性能提出了更高的要求。如何提高選擇性、長(zhǎng)期工作穩(wěn)定性以及響應(yīng)-恢復(fù)速度、降低功耗和成本是新型氣體傳感器面臨的主要挑戰(zhàn)。因此,開(kāi)發(fā)新型氣敏材料、探索新的氣敏機(jī)制和設(shè)計(jì)新的器件結(jié)構(gòu)成為該領(lǐng)域的重要研究方向。首先就氣敏材料而言,目前廣泛應(yīng)用的是金屬氧化物半導(dǎo)體材料。但是基于金屬氧化物半導(dǎo)體材料的氣體傳感器多存在工作溫度高、選擇性差等問(wèn)題,因此實(shí)用性強(qiáng)、高性能、低成本氣體傳感器的開(kāi)發(fā)還有許多困難需要克服。材料科學(xué)的新技術(shù)為我們解決上述問(wèn)題提供了有效途徑。例如,針對(duì)氣體傳感器工作溫度高、選擇性差等缺點(diǎn),可以通過(guò)對(duì)敏感材料進(jìn)行貴金屬表面修飾的方法加以改善。其次,就氣敏元件的構(gòu)建而言,新涌現(xiàn)的微納米操控技術(shù)也可以大大降低微納米結(jié)構(gòu)器件構(gòu)建對(duì)設(shè)備的要求和工藝難度,本課題采用介電泳技術(shù)操控一維納米材料,將納米材料跨界在電極兩側(cè),構(gòu)建成氣體傳感器。本課題采用化學(xué)水浴法制備氧化鋅納米棒,并對(duì)其氣敏特性進(jìn)行了研究。然而,由于單純的氧化鋅納米棒在氣體選擇性、響應(yīng)-恢復(fù)速度、靈敏度等方面,還難以滿足實(shí)際應(yīng)用的需要,因此對(duì)氧化鋅納米棒做進(jìn)一步的修飾或復(fù)合處理具有極其重要的意義。另外,為了有效利用一維納米材料在結(jié)構(gòu)上的特殊優(yōu)勢(shì),構(gòu)建基于一維納米材料有序定向排列的器件是必然方向�？紤]降低設(shè)備要求和工藝難度,本課題采用了相對(duì)簡(jiǎn)單的介電泳操控技術(shù)構(gòu)建了一維氧化鋅有序排列的氣體傳感器用于材料氣敏特性研究。本課題研究分為三個(gè)部分:第一部分:利用光化學(xué)沉積法,在氧化鋅納米棒表面進(jìn)行銀納米顆粒修飾。實(shí)驗(yàn)中用聚乙烯吡咯烷酮作為穩(wěn)定劑,使貴金屬Ag納米顆粒分散地附著在氧化鋅納米棒表面,形成Ag/ZnO異質(zhì)結(jié)。除此之外,本實(shí)驗(yàn)還對(duì)比了兩種不同的電極材料,即鎳酸鑭氧化物導(dǎo)體電極和Ag-Pd貴金屬電極。實(shí)驗(yàn)發(fā)現(xiàn)分別采用兩種電極材料的氣敏元件在氣敏特性方面沒(méi)有明顯差異,表明廉價(jià)的鎳酸鑭氧化物導(dǎo)體電極可以替代貴金屬電極。第二部分:用光化學(xué)沉積法在氧化鋅納米棒表面制備Cu O/ZnO異質(zhì)結(jié),并測(cè)試其氣敏特性。本實(shí)驗(yàn)采用不同濃度(25μM、50μM和200μM)的硝酸銅的水溶液作為前驅(qū)液,紫外燈下照射一段時(shí)間后得到CuO/ZnO異質(zhì)結(jié)復(fù)合材料。并對(duì)樣品進(jìn)行氣敏特性測(cè)試,結(jié)果發(fā)現(xiàn)樣品對(duì)硫化氫最敏感,最佳工作溫度為250℃。第三部分:制備MWCNT/Zn O異質(zhì)結(jié)復(fù)合材料,并在室溫下測(cè)試其氣敏特性,測(cè)試結(jié)果表明該結(jié)構(gòu)在室溫下對(duì)二氧化氮?dú)怏w比較敏感。并探討MWCNT/ZnO異質(zhì)結(jié)復(fù)合材料獲得最佳氣敏特性時(shí),多壁碳納米管(MWCNT)和氧化鋅納米棒的比例。
[Abstract]:With the deterioration of the ecological environment, the high efficiency of the environment and the urgent need of real-time monitoring put forward higher requirements for the performance of gas sensors. How to improve selectivity, long-term stability, response-recovery speed, and reduce power consumption and cost are the main challenges facing the new gas sensor. Therefore, developing new gas sensing materials, exploring new gas sensing mechanisms and designing new device structures are important research directions in this field. Firstly, as far as gas sensing materials are concerned, metal oxide semiconductors are widely used at present. However, many gas sensors based on metal oxide semiconductor materials have many problems such as high working temperature and poor selectivity, so there are still many difficulties to overcome in the development of gas sensors with high practicability, high performance and low cost. The new technology of material science provides an effective way for us to solve the above problems. For example, in view of the shortcomings of high temperature and poor selectivity of gas sensors, the surface modification of sensitive materials can be improved by the method of precious metal surface modification. Secondly, as far as the construction of gas sensors is concerned, the newly emerged micro / nano manipulation technology can greatly reduce the equipment requirements and process difficulties in the fabrication of micro / nano structure devices. In this paper, one dimensional nanomaterials are manipulated by using dielectric electrophoresis technology. A gas sensor was constructed by crossing the nanomaterials on both sides of the electrode. In this paper, zinc oxide nanorods were prepared by chemical water bath method and their gas sensing characteristics were studied. However, the pure ZnO nanorods are difficult to meet the needs of practical application in gas selectivity, response-recovery speed, sensitivity and so on. Therefore, further modification or composite treatment of ZnO nanorods is of great significance. In addition, in order to effectively utilize the special advantages of one-dimensional nanomaterials in structure, it is necessary to construct the devices based on ordered orientation of one-dimensional nanomaterials. In order to reduce the equipment requirement and process difficulty, a one-dimensional gas sensor with ordered arrangement of zinc oxide was constructed by using a relatively simple meso-electrophoretic manipulation technique to study the gas sensing characteristics of materials. The research is divided into three parts: the first part: the surface of zinc oxide nanorods was modified with silver nanoparticles by photochemical deposition. Using polyvinylpyrrolidone as stabilizer, noble metal Ag nanoparticles were dispersed on the surface of zinc oxide nanorods to form Ag/ZnO heterostructures. In addition, two different electrode materials, lanthanum nickel oxide conductor electrode and Ag-Pd noble metal electrode, were compared. It is found that there is no obvious difference in gas sensitivity between the two kinds of electrode materials, which indicates that the cheap lanthanum nickel oxide conductor electrode can replace the noble metal electrode. Part two: the Cu O/ZnO heterojunction was prepared on the surface of ZnO nanorods by photochemical deposition, and its gas sensing properties were tested. In this experiment, the aqueous solution of copper nitrate with different concentrations (25 渭 m ~ (50 渭 M) and 200 渭 M) was used as the precursor, and the CuO/ZnO heterojunction composite was obtained after irradiation by ultraviolet lamp for a period of time. The results show that the sample is most sensitive to hydrogen sulfide and the optimum working temperature is 250 鈩，

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