本文關(guān)鍵詞：電紡氧化錫基納米纖維材料的制備及其丙酮傳感性能研究　出處：《吉林大學(xué)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 靜電紡絲 納米纖維 丙酮傳感 摻雜 異質(zhì)結(jié) 貴金屬負(fù)載

【摘要】：為了應(yīng)對(duì)日益嚴(yán)重的空氣污染,研究對(duì)于以丙酮為代表的揮發(fā)性有機(jī)空氣污染物具有優(yōu)良敏感性質(zhì)的高效率氣體傳感器具有十分重要的意義。SnO_2基敏感材料在氣體傳感研究領(lǐng)域中一直扮演著比較重要的角色,在環(huán)境污染物氣體的檢測(cè)和易燃易爆氣體的報(bào)警等領(lǐng)域具備巨大的應(yīng)用潛力。與傳統(tǒng)的零維和二維納米材料相比,一維納米材料由于其自身獨(dú)特的結(jié)構(gòu)和特性,在快速識(shí)別信號(hào)和電子傳輸?shù)确矫婢哂泻艽髢?yōu)勢(shì),因而在納米傳感器研究領(lǐng)域受到格外重視。靜電紡絲是一種成本較為低廉、操作較為簡(jiǎn)單的制備一維納米材料的方法。該方法得到的一維納米纖維,其組成和結(jié)構(gòu)可以便捷地進(jìn)行精確設(shè)計(jì)和調(diào)控,較大的比表面積為氣體分子在材料表面提供了更多的反應(yīng)活性位點(diǎn),有利于提高氣體響應(yīng);納米纖維較大的宏觀長(zhǎng)度和長(zhǎng)徑比,也十分有利于電信號(hào)的快速傳遞,從而獲得快速的響應(yīng)恢復(fù)特性。本論文采用靜電紡絲技術(shù)制備了一系列SnO_2基一維納米纖維材料,通過采用摻雜、構(gòu)筑異質(zhì)結(jié)以及貴金屬負(fù)載等方法對(duì)納米纖維的組成結(jié)構(gòu)進(jìn)行定向設(shè)計(jì)調(diào)控來提高氣體傳感特性,并深入研究這些材料作為丙酮敏感材料所表現(xiàn)出來的性能,建立組成結(jié)構(gòu)和性能之間的關(guān)系,從而為進(jìn)一步拓展一維納米纖維在環(huán)境監(jiān)測(cè)和保護(hù)領(lǐng)域的應(yīng)用奠定基礎(chǔ)。主要內(nèi)容分為以下三部分:1.金屬離子摻雜是目前應(yīng)用最廣泛的可以有效提高金屬氧化物半導(dǎo)體氣體傳感性能的方法之一。我們基于納米纖維的獨(dú)特結(jié)構(gòu)以及組成可控的特點(diǎn),以高分子PVP為模板,利用靜電紡絲結(jié)合高溫后處理技術(shù)制備了一系列堿土金屬離子摻雜的SnO_2納米纖維,并研究了它們對(duì)于丙酮的傳感性能,詳細(xì)地討論了不同堿土金屬離子的摻雜機(jī)制。首先,我們以電紡SnO_2納米纖維作為本征材料,選擇Sr~(2+)對(duì)其進(jìn)行間隙摻雜,通過堿土金屬摻雜對(duì)于SnO_2晶體生長(zhǎng)的抑制作用對(duì)SnO_2納米纖維的晶粒尺寸進(jìn)行調(diào)控,從而進(jìn)一步影響改善其氣體傳感性能。當(dāng)Sr~(2+)摻雜量為1 at%時(shí),納米纖維的晶粒尺寸最小;相應(yīng)地,丙酮傳感性能此時(shí)最佳,對(duì)100 ppm丙酮的響應(yīng)值(~25)為純SnO_2納米纖維的2倍,響應(yīng)時(shí)間和恢復(fù)時(shí)間均為6 s左右,且兼具優(yōu)秀的選擇性和穩(wěn)定性。為了進(jìn)一步驗(yàn)證堿土金屬摻雜對(duì)于SnO_2納米纖維的氣體傳感性能的提高作用,我們又選擇了另外一種比Sr~(2+)半徑稍小的堿土金屬離子Ca~(2+)對(duì)SnO_2納米纖維進(jìn)行微量摻雜。當(dāng)Ca~(2+)摻雜量為0.8 at%時(shí),納米纖維對(duì)丙酮的傳感性能最佳,對(duì)100 ppm丙酮的響應(yīng)值(~27)為純SnO_2納米纖維的2.3倍;響應(yīng)時(shí)間約為6 s,恢復(fù)時(shí)間約為3 s,選擇性和穩(wěn)定性也較為優(yōu)異。通過對(duì)這些提高的傳感性能的研究和探討,發(fā)現(xiàn)除了堿土金屬抑制劑對(duì)于晶粒生長(zhǎng)的控制作用外,部分Ca~(2+)在摻雜過程中替代Sn~(4+)位點(diǎn)而導(dǎo)致的晶格缺陷和氧空位同樣在氣敏性能的增強(qiáng)中發(fā)揮著重要作用。2.在氣體敏感材料中構(gòu)建異質(zhì)結(jié)同樣是一種提高半導(dǎo)體氣體傳感性能的重要方法。我們充分利用納米纖維結(jié)構(gòu)組成可控的特點(diǎn),通過靜電紡絲技術(shù)將不同的納米異質(zhì)結(jié)引入SnO_2納米纖維中,并研究了不同異質(zhì)組分比例對(duì)丙酮的傳感性能所造成的影響,詳細(xì)地討論了異質(zhì)結(jié)增強(qiáng)氣體傳感性能的作用機(jī)理。首先,我們以高分子PVP為模板,運(yùn)用靜電紡絲結(jié)合高溫后處理技術(shù)制備了組分分布均勻的p-Cr_2O_3/n-SnO_2復(fù)合納米纖維,并詳細(xì)考察了其丙酮敏感性能。實(shí)驗(yàn)結(jié)果表明Cr_2O_3/SnO_2 p-n異質(zhì)結(jié)的引入極大地改善了SnO_2納米纖維的丙酮傳感性能,以100 ppm丙酮為目標(biāo)氣體,當(dāng)Cr_2O_3組分在復(fù)合纖維中的含量為3 at%時(shí),Cr_2O_3/SnO_2復(fù)合納米纖維的響應(yīng)(~46,280 oC)最大,為純SnO_2納米纖維響應(yīng)(~12,300 o C)的3.8倍;響應(yīng)時(shí)間僅為4s,恢復(fù)時(shí)間約為5s;對(duì)丙酮的飽和濃度(20,000 ppm)大大超過純SnO_2納米纖維(5,000 ppm),抗?jié)裥浴⑦x擇性和穩(wěn)定性優(yōu)異。為了研究同型異質(zhì)結(jié)對(duì)于氣敏性能的影響,我們又運(yùn)用靜電紡絲技術(shù)制備了n-Cd O/n-SnO_2復(fù)合納米纖維,并詳細(xì)考察了其丙酮傳感性能。實(shí)驗(yàn)結(jié)果表明相比于純SnO_2納米纖維,CdO/SnO_2異質(zhì)結(jié)復(fù)合納米纖維表現(xiàn)出顯著提高的丙酮敏感特性。對(duì)于性能最出色的Cd O含量為5 at%的CdO/SnO_2復(fù)合納米纖維,其對(duì)100 ppm丙酮的響應(yīng)(~50,280 o C)為純SnO_2納米纖維(~12,300 o C)的4.2倍;響應(yīng)時(shí)間約為6 s,恢復(fù)時(shí)間僅為5 s;對(duì)丙酮的飽和濃度(20,000 ppm)大大超過純SnO_2納米纖維(5,000 ppm),抗?jié)裥�、選擇性和穩(wěn)定性優(yōu)異。3.本體材料負(fù)載貴金屬已經(jīng)被證明是一種提高氣體響應(yīng)和降低工作溫度的有效方法,但目前大部分這方面工作所使用的都是多步后處理方法,即先制備本體材料,再通過浸漬、沉積、濺射等方法在材料表面修飾貴金屬,過程較為繁瑣且材料利用率較低。由于靜電紡絲的各組分前驅(qū)體是在溶液相中混合均勻的,因此這種一步直接的方法制備出的一維納米材料各組分分布均勻,對(duì)于提高性能和降低貴金屬負(fù)載的成本十分有利。我們基于靜電紡絲技術(shù),以高分子PVP為模板制備了負(fù)載Au的SnO_2基復(fù)合納米纖維,通過引入Au成功降低了對(duì)丙酮的操作溫度,并進(jìn)一步提高了響應(yīng)特性。首先,我們將Au引入到SnO_2納米纖維中,得到的Au/SnO_2復(fù)合納米纖維對(duì)于丙酮的操作溫度大幅降低,響應(yīng)明顯提升;在220 oC的最佳工作溫度下對(duì)100 ppm丙酮的響應(yīng)值達(dá)到了57,響應(yīng)時(shí)間為8.5 s,恢復(fù)時(shí)間為7 s;丙酮飽和濃度達(dá)到了30,000 ppm,經(jīng)60天長(zhǎng)期放置后依舊能夠保持響應(yīng)信號(hào)的穩(wěn)定。此外,對(duì)Au/SnO_2肖特基結(jié)和貴金屬催化劑在性能增強(qiáng)中所起的作用也進(jìn)行了討論。隨后,針對(duì)Au/SnO_2復(fù)合納米纖維的丙酮選擇性不夠特別突出的問題,我們通過引入第三方非本征稀土金屬氧化物Eu2O3,利用Eu2O3和Au的協(xié)同作用成功地改善了丙酮選擇性;所制備的Eu_2O_3/Au/SnO_2復(fù)合納米纖維在200 o C的最佳工作溫度下對(duì)100 ppm丙酮的響應(yīng)值達(dá)到了65,響應(yīng)時(shí)間為11.7 s,恢復(fù)時(shí)間為6.5 s;丙酮檢測(cè)下限達(dá)到了ppb級(jí),飽和濃度為30,000 ppm,可測(cè)濃度范圍更寬,且重復(fù)穩(wěn)定性優(yōu)異。
[Abstract]:In order to cope with the increasingly serious air pollution, high efficiency gas sensor has excellent sensitive properties for volatile organic air pollutants using acetone as the representative of the significance of.SnO_2 based sensitive materials plays a very important role has been more important in the research field of gas sensing, have great application potential in the field of environmental pollutants detection alarm gas flammable and explosive gases. Compared with the traditional zero and two dimensional nano materials, nano materials because of its unique structure and characteristics, has great advantages in the rapid identification of electronic signals and transmission, which has been in the field of nano sensor attention. Electrospinning is a relatively inexpensive, preparation method one dimensional nano materials. The operation is relatively simple one-dimensional nanofibers obtained by this method, the composition and structure of Convenient to carry out precise design and control of large surface area for gas molecules on the surface of the material provides more reactive sites, improve the gas response; macroscopic length nanofibers and larger length diameter ratio, also very fast to signal transmission, to obtain fast response characteristics. In a series of SnO_2 based one-dimensional nanofibers were fabricated by electrospinning, by doping, construct heterojunction and noble metal loading method of the structure on the nanometer fiber directional regulation design to improve gas sensing properties, performance and in-depth study of these materials as acetone sensitive material, the relationship between the establishment of structure and performance, so as to lay the foundation for further development of application of one-dimensional nano fiber in the field of environmental monitoring and protection. The main content is divided into the following The three part: 1. metal ion doping is currently the most widely used can be one method of metal oxide semiconductor gas sensing performance effectively. Our unique structure of nano fiber and characteristics of controllable composition based on polymer PVP as template by electrospinning combined with high temperature postprocessing technology for SnO_2 nano fiber series of alkaline earth metal ions doped the preparation and study their sensing properties for acetone, different doping mechanism of alkaline earth metal ions were discussed in detail. First, we use the electrospun SnO_2 nanofibers as intrinsic materials, Sr~ (2+) doping on the gap, the alkaline earth metal doped SnO_2 crystal growth inhibitory effect of grain size on SnO_2 nano fiber regulation, so as to further improve the gas sensing performance. When Sr~ (2+) doped with 1 at%, grain size of nano fiber Inch minimum; accordingly, acetone sensing performance at best, in response to 100 ppm of acetone (~25) value was 2 times of pure SnO_2 nanofibers, the response time and recovery time was about 6 s, and has excellent selectivity and stability. In order to improve the effect of further verification of the gas sensing performance of alkaline earth metal doping on SnO_2 nano fiber, we chose another than Sr~ (2+) alkaline earth metal ions Ca~ radius smaller (2+) micro doping on SnO_2 nano fiber. When Ca~ (2+) doped with 0.8 at%, nano fiber to acetone sensing performance is the best response to the value of 100 ppm acetone (~27) is 2.3 times that of pure SnO_2 nanofibers; the response time is about 6 s, the recovery time is about 3 s, selectivity and stability are excellent. Through the research and Discussion on the sensing performance improvement, found that in addition to grain growth inhibitor for alkaline earth metal The control effect, part of the Ca~ (2+) instead of Sn~ during doping (4+) lattice defects and oxygen vacancies caused the same sites in enhanced gas sensing properties play an important role in the construction of.2. gas sensitive material in the heterojunction is also an important method to improve the performance of semiconductor gas sensing characteristics we. Make full use of nano fiber structure controllable, via electrospinning of different nano heterostructures into SnO_2 nanofibers, and studied the influence of different heterogeneous groups caused by the sensing performance ratio of acetone, discussed in detail the heterojunction enhancement mechanism of the gas sensing performance. First, we take PVP as the polymer the use of templates, electrospinning with high temperature postprocessing technology for p-Cr_2O_3/n-SnO_2 composite nanofibers uniformly distributed components were prepared, and a detailed study of its acetone sensitive properties. The results of experiments The Cr_2O_3/SnO_2 p-n heterojunction into acetone and greatly improve the sensing properties of SnO_2 nano fiber, 100 ppm acetone as the target gas, when the content of Cr_2O_3 component in the composite fiber is 3 at%, the response of Cr_2O_3/SnO_2 composite nanofibers (~46280 oC), in response to pure SnO_2 nanofibers (~12300 o C 3.8 times); response time is only 4S, the recovery time is about 5S; the saturated concentration of acetone (20000 ppm) significantly more than the pure SnO_2 nanofibers (5000 ppm), moisture resistance, selectivity and excellent stability. In order to study the heterojunction effect on gas sensing properties, we use technology the electrospun n-Cd O/n-SnO_2 composite nanofibers were prepared and investigated with the acetone sensing performance. Experimental results show that compared to pure SnO_2 nanofibers, CdO/SnO_2 heterojunction composite nanofibers showed a significantly higher sensitivity of acetone The content of O Cd. For the best performance of CdO/SnO_2 composite nano fiber 5 at%, its response to 100 ppm acetone (~50280 o C) for pure SnO_2 nanofibers (~12300 o C) 4.2 times; the response time is about 6 s, the recovery time is only 5 s; on the saturated concentration of acetone (20000 ppm) significantly more than the pure SnO_2 nanofibers (5000 ppm), moisture resistance, excellent selectivity and stability of.3. bulk materials supported noble metal has been proved to be an effective method to improve the gas response and reduce the temperature, but the use of most of this work is the processing method of multi step, i.e. preparation of bulk materials, through impregnation deposition, sputtering method in material surface modification of precious metals, the process is more complicated and the material utilization rate is relatively low. Because each electrospinning precursor is divided evenly mixed in the solution phase, so that the one step direct method One dimensional nano materials prepared were divided evenly distributed, to improve the performance and reduce the cost of the precious metal load is very favorable. We electrospinning technology based on SnO_2 composite nanofiber supported Au templates for preparation of polymer PVP, by introducing Au successfully reduced to acetone operating temperature, and further improve the response characteristics. Firstly, we introduce the Au into SnO_2 nanofibers, Au/SnO_2 nanofibers obtained for acetone operating temperature significantly reduced, significantly enhance the response; at the optimal temperature under 220 oC in response to 100 ppm acetone value reached 57, the response time is 8.5 s, the recovery time was 7 s; the saturated concentration of acetone reached 30000 ppm, after 60 days after long period of storage is still able to maintain the stability of the response signal. In addition, the Au/SnO_2 Schottky junction and noble metal catalyst in the performance enhancement of it Are discussed. Then, the Au/SnO_2 composite nanofibers acetone selective enough prominent problem, we introduce third extrinsic rare earth metal oxide Eu2O3, successfully improved the selectivity of acetone by the synergistic effect of Eu2O3 and Au; in response to 100 ppm acetone optimum temperature for Eu_2O_3/Au/SnO_2 composite nanofibers prepared in 200 o C value reached 65, the response time is 11.7 s, the recovery time is 6.5 s; the detection limit of acetone reached ppb and the saturation concentration of 30000 ppm, measured concentrations of a wide range of heavy and complex stability is excellent.

【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TQ340.64

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7 張玉軍;陸春;陳平;李建豐;于祺;;溶劑在高壓靜電紡絲中的作用[A];2005年全國(guó)高分子學(xué)術(shù)論文報(bào)告會(huì)論文摘要集[C];2005年

8 萬玉芹;何吉?dú)g;俞建勇;吳s，

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