镍基介孔金属氧化物的制备及其在气体传感器中的应用

发布时间：2018-08-06 22:12

【摘要】：随着经济的发展与和人们对矿井瓦斯气体爆炸、工业毒害气体泄漏、室内空气污染等环境安全问题的日益重视,开发高敏感性、高选择性、高稳定性的气敏材料和先进气体传感器技术对保障国民生产和生活的安全具有极为重要的意义。介孔材料具有大的比表面积、高的孔容、可调的孔径等诸多优点,是一类潜在的气敏材料,吸引了研究者广泛的关注。本论文采用硬模板法合成了几种不同孔结构、孔尺寸、孔壁厚度及孔壁成份的镍基氧化物介孔材料,研究了结构参数与化学组成对其气敏性能的影响：1、通过控制不同的水热合成温度,合成了一系列具有不同孔径(5.7～9.4 nm)和比表面积的介孔氧化硅KIT-6,并以其为硬模板,采用纳米浇筑路线,制备了具有不同孔壁厚度(5.1～9.4nm)的介孔氧化镍。XRD、N2物理吸附和TEM表征结果表明,所制备的介孔氧化镍具有高度有序的介孔结构、大的比表面积、高的孔容以及可调的介孔分布(从单介孔到双介孔)。我们研究了其对甲醛气体的敏感性,发现介孔氧化镍的敏感度高于体相氧化镍,在380 ppm甲醛气体浓度下大约是体相氧化镍的4-10倍；另外,我们发现介孔尺寸越大、孔壁厚度越小,其对甲醛气体的敏感度越高,具有双介孔分布和薄孔壁的介孔氧化镍在最佳工作温度300℃下对380 ppm甲醛的敏感度为20.5,高于所合成的其它介孔氧化镍材料。2、气敏材料的化学组成对其气敏性能也具有重要的影响。我们以不同比例硝酸铁与硝酸镍(Fe/Ni=0.01～0.35)混合溶液为前驱体,40℃水热合成的KIT-6分子筛为硬模板,采用纳米浇筑路线合成了一系列的介孔复合材料。广角XRD只检测到氧化镍的衍射峰表明Fe主要以离子形式进入了氧化镍的晶格,未出现分离相氧化铁。EDS表征结果表明所合成的Fe掺杂介孔氧化镍复合材料的理论掺杂量与实际掺杂量相吻合。小角XRD和TEM表征结果表明硝酸铁的引入影响了氧化镍在KIT-6孔道中连续生长,随着Fe掺杂量的增加所制备材料的介观有序性逐渐下降。N2物理吸附测试表明所制备材料保持了大的比表面积、高的孔容以及双介孔结构。甲醛气体敏感性研究发现掺杂Fe的介孔氧化镍对甲醛的敏感度有了显著的提高,当Fe/Ni=0.20时,敏感度最高(在90 ppm甲醛浓度下可达554),是纯介孔氧化镍的65倍。3、进一步增加硝酸铁与硝酸镍混合溶液中硝酸铁的比例(Fe/Ni-2),并提高热处理温度,也合成了一系列具有不同孔壁厚度的具有尖晶石结构的有序介孔NiFe204,并对其进行了小角XRD、N2物理吸附和TEM等一系列表征。我们研究了其对甲醛气体的敏感性,测试结果表明介孔NiFe2O4对甲醛气体具有高的敏感性(在46 ppm甲醛浓度下可达60)。
[Abstract]:With the development of economy and people's increasing attention to mine gas and gas explosion, industrial toxic gas leakage, indoor air pollution and other environmental safety problems, it is of great significance to develop Gao Min sensibility, high selectivity, high stability gas sensitive materials and advanced gas sensor technology to ensure the safety of national production and life. Mesoporous materials have many advantages, such as large specific surface area, high pore volume, adjustable aperture and so on. It is a kind of potential gas sensitive material, which attracts the attention of researchers. In this paper, several kinds of nickel based oxide mesoporous materials with different pore structure, pore size, hole wall thickness and pore wall composition have been synthesized by hard template method, and the structure parameters and chemical properties are studied. 1, a series of mesoporous silica KIT-6 with different pore size (5.7 to 9.4 nm) and specific surface area were synthesized by controlling different hydrothermal synthesis temperatures, and the Mesoporous Nickel Oxide.XRD with different thickness of the pore wall (5.1 ~ 9.4nm) was prepared with its hard template, and the physical absorption of N2 physical absorption was made. The results of TEM characterization show that the prepared mesoporous nickel oxide has a highly ordered mesoporous structure, large specific surface area, high pore volume and adjustable mesoporous distribution (from single mesoporous to double mesoporous). We studied its sensitivity to formaldehyde gas, and found that the sensitivity of Mesoporous Nickel oxide is higher than that of the bulk phase of nickel oxide in 380 ppm formaldehyde gas. The concentration is about 4-10 times that of the body phase nickel oxide. In addition, the greater the size of the mesoporous, the smaller the thickness of the pore wall, the higher the sensitivity to the formaldehyde gas. The sensitivity of the Mesoporous Nickel Oxide with a double mesoporous distribution and thin hole wall at the optimum working temperature of 300 to 380 ppm formaldehyde is 20.5, which is higher than that of the other Mesoporous Nickel oxide materials. Material.2, the chemical composition of gas sensitive materials also has an important influence on its gas sensitivity. We use different proportions of iron nitrate and nickel nitrate (Fe/Ni=0.01 ~ 0.35) mixed solution as precursors, KIT-6 molecular sieves synthesized at 40 C as hard templates, and a series of mesoporous composite materials are synthesized by nano pouring route. Wide angle XRD only detects oxygen. The diffraction peak of nickel showed that Fe entered the lattice of nickel oxide mainly in the form of ion. The result of.EDS characterization showed that the theoretical doping amount of the synthesized Fe Doped Mesoporous Nickel oxide composite was in agreement with the actual doping amount. The characterization of small angle XRD and TEM showed that the introduction of iron nitrate influenced the nickel oxide in the KIT-6 hole. The mesoscopic order of the prepared materials gradually decreased with the increase of Fe doping content. The physical adsorption test of.N2 showed that the prepared material maintained a large specific surface area, high pore volume and double mesoporous structure. The sensitivity of formaldehyde to formaldehyde was significantly improved by the study of the sensitivity of the Mesoporous Nickel oxide doped with Fe. Fe/Ni=0.20, with the highest sensitivity (up to 554 at 90 ppm formaldehyde concentration), is 65 times.3 of pure Mesoporous Nickel oxide, and further increases the proportion of iron nitrate (Fe/Ni-2) in the mixed solution of iron nitrate and nickel nitrate (Fe/Ni-2), and improves the heat treatment temperature. A series of ordered mesoporous NiFe204 with spinel structure with different thickness of the pore wall is also synthesized, and the NiFe204 is also synthesized. A series of characterization of small angle XRD, N2 physical adsorption and TEM were carried out. We studied its sensitivity to formaldehyde gas. The test results showed that mesoporous NiFe2O4 had high sensitivity to formaldehyde gas (up to 60 at 46 ppm formaldehyde concentration).
【学位授予单位】：宁夏大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.4

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