發(fā)布時間：2018-04-02 03:08

  本文選題：金屬氧化物　切入點：二甲苯　出處：《吉林大學(xué)》2017年碩士論文

【摘要】：社會的發(fā)展帶來了物質(zhì)的極大豐富,然而金無足赤,大多數(shù)材料都是利弊并存的,例如二甲苯,作為一種重要的化工原料和有機溶劑,可用于生產(chǎn)染料、涂料、樹脂和油墨等,但其本身的毒性也使它成為一種典型的揮發(fā)性有機化合物污染源,同時其可燃性,也決定了它在生產(chǎn)過程中的危險性。因此,無論在日常生活中還是工業(yè)生產(chǎn)中,對二甲苯的實時監(jiān)測都關(guān)系到人們的身體健康和生命安全�？梢员O(jiān)測二甲苯的方法和工具有很多,但是相比之下,半導(dǎo)體式氣體傳感器以其小巧便攜、響應(yīng)迅速、廉價易得的優(yōu)點,獲得了人們越來越多的關(guān)注。而作為半導(dǎo)體式氣體傳感器的關(guān)鍵部分——半導(dǎo)體氣敏材料的敏感特性對傳感器的性能起著決定性的作用。從起初的SnO_2和ZnO,到后來的WO_3、Fe_2O_3、In_2O_3、Co_3O_4、NiO等等,再到后來的LaFeO_3、ZnCo_2O_4,以及一些硫化物,目前,被研究和應(yīng)用于氣敏領(lǐng)域的材料種類紛繁復(fù)雜,但作為氣敏材料的主流,金屬氧化物依然是研究氣敏規(guī)律的熱門選擇。本文針對二甲苯氣體檢測,以金屬氧化物為基體材料,通過摻雜、復(fù)合手段,旨在制備出性能優(yōu)良的氣體傳感器。實驗思路和研究內(nèi)容如下:1.發(fā)現(xiàn)了一種制備具有孔隙的Co_3O_4棒狀材料的方法�？紫犊梢蕴岣卟牧系谋缺砻娣e,改變材料的表面狀態(tài),同時,棒狀大結(jié)構(gòu)可以使材料保持較好的穩(wěn)定性。在氣敏性能方面,對甲苯、甲醛、乙醇等都表現(xiàn)出響應(yīng),雖然對二甲苯的響應(yīng)最高,但依然表現(xiàn)出單一材料選擇性不夠好的缺點,同時對二甲苯的響應(yīng)恢復(fù)速度較慢也說明了其結(jié)構(gòu)有待進一步改善,因此,開展了第二個實驗。2.采用水熱法制備了具有分等級結(jié)構(gòu)的Co_3O_4微球,并對其進行了不同比例的Cr摻雜,研究了它們對揮發(fā)性有機化合物的氣敏性能,尤其是對二甲苯的敏感特性。Cr摻雜的Co_3O_4材料相對于純相的Co_3O_4材料,對甲醛、乙醇等響應(yīng)變化不大,但對二甲苯的響應(yīng)有了明顯的提高,且在摻雜比例為5 at%的時候提高的最多(5 ppm二甲苯氣體氛圍中響應(yīng)為6.38,相對與純相Co_3O_4對5 ppm二甲苯的響應(yīng)1.29,提高了近4倍),這種提高也改善了材料的選擇性,降低了檢測過程中其它氣體帶來的信噪比,并且響應(yīng)和恢復(fù)過程進行速度很快,在30 s之內(nèi)均可完成。但對于Cr摻雜的作用,根據(jù)表面電阻控制理論,認為在接近表面位置的作用可能更大,因此設(shè)計成適當(dāng)?shù)漠愘|(zhì)結(jié)型材料,應(yīng)該會有更好的氣敏表現(xiàn),故而進行了第三個實驗。3.設(shè)計并制備了以WO_3為基體材料,在其表面生長Cr_2O_3粒子,進而形成異質(zhì)結(jié)型結(jié)構(gòu)的氣敏材料。制備方法采用了兩步水浴法,其中,制備的WO_3呈具有分等級結(jié)構(gòu)的花狀粒子,其片狀結(jié)構(gòu)有較長的寬度,給二次生長的粒子提供了附著點,同時又有較薄的厚度,有利于更好地發(fā)揮出異質(zhì)結(jié)的作用。對比由Cr_2O_3-WO_3制得的氣體傳感器和由WO_3材料制得的氣體傳感器,異質(zhì)結(jié)構(gòu)顯著提高了材料對二甲苯氣體的響應(yīng),且響應(yīng)恢復(fù)速度依然較快,響應(yīng)過程和恢復(fù)過程分別在5 s和20 s內(nèi)就可完成。
[Abstract]:The development of society has brought abundant materials, however, most of the materials are None is perfect, both advantages and disadvantages, such as xylene, as an important chemical raw material and organic solvent, can be used in the production of dyes, paints, inks and resins, but its toxicity also makes it become a kind of typical volatile organic compounds pollution at the same time, the source of combustible, it also determines the risk in the production process. Therefore, both in daily life and industrial production, real time monitoring of p-xylene is related to people's health and life safety. There are many methods and tools for monitoring xylene, but compared to semiconductor gas the sensor with its compact and portable, fast response, the advantages of cheap, get more and more attention. As a key part of semiconductor gas sensors, semiconductor gas The sensitive characteristics of sensitive materials and the performance of the sensor plays a decisive role. From the beginning of the SnO_2 and ZnO, then WO_3, Fe_2O_3, In_2O_3, Co_3O_4, NiO and so on, then later LaFeO_3, ZnCo_2O_4, and some sulfides, at present, are numerous kinds of material research and application in gas field is complex, but as the mainstream of gas sensitive materials, metal oxide is still a popular choice of gas sensitive rules. In this paper the xylene gas detection, using metal oxide as base material, by means of doping, composite, in order to prepare gas sensor with excellent performance. The ideas and research contents are as follows: 1. it is found that the method of Co_3O_4 rod material the preparation has a pore. Pore can increase the surface area of the material, changing the surface state of the material at the same time, rodlike structure can make the materials to maintain stability better. In the gas sensing performance Formaldehyde, ethanol, toluene, etc. have shown a response, although the highest response of p-xylene, but still showed the single material selectivity problems at the same time, the slow recovery of p-xylene response also shows that the structure needs to be further improved, therefore, carried out second experiments with.2. Co_3O_4 microspheres prepared graded structure by hydrothermal method, and has carried on the different proportion of Cr doping were studied on the gas sensing properties of volatile organic compounds, especially the sensitive characteristics of.Cr doped Co_3O_4 materials for p-xylene phase pure Co_3O_4 material of formaldehyde, ethanol response changed little, but the response has been significantly xylene to improve, and when the doping amount is 5 at% when the maximum increase (5 ppm xylene gas atmosphere response was 6.38, compared with pure phase Co_3O_4 5 ppm two tnu-9 response 1.29,. The high of nearly 4 times), this increase also improved material selectivity, reduce the other gas detection process to bring the signal-to-noise ratio, and the response and recovery process is very fast, can be completed within 30 s. But the effects of doping Cr, according to the control theory of surface resistance, in that position close to the surface the effect may be greater, so the design of appropriate heterostructure materials, gas sensing performance should be better, therefore conducted third experiments on.3. was designed and fabricated with WO_3 as matrix material, growing on the surface of Cr_2O_3 particles, thus forming gas sensitive material heterojunction structure. Preparation the method adopts two step water bath, the prepared WO_3 was with flower shaped particle graded structure, the lamellar structure of long width, provides two times the growth of particle attachment point, and a thinner thickness, is conducive to better play A heterojunction. By comparing the Cr_2O_3-WO_3 gas sensor and gas sensor prepared by WO_3 material prepared by heterogeneous structure significantly improves the material response to xylene gas, and the response and recovery speed is still fast, the response and recovery process were 5 s and 20 s can be finished.

【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TP212

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本文編號：1698502