二氧化锡与伽马氧化铝纳米材料表面结构的固体核磁共振研究

发布时间：2018-06-07 17:36

本文选题：纳米金属氧化物 + 固体核磁共振　；参考：《南京大学》2015年硕士论文

【摘要】：近些年来,纳米金属氧化物在能源、催化、环境以及生物等领域的应用中表现出了巨大的潜力。纳米材料的表面结构与其性能密切相关,因此必须在原子、分子层次上掌握这些结构信息。固体核磁共振是一种研究固体材料短程、中程有序的有力工具,具备能够针对特定元素(原子核)进行分析,具有保留样品的原有物相、可无损伤检测,定量研究等特点。本论文以固体核磁共振方法为核心,辅以X射线衍射、透射电子显微镜、傅里叶变换红外光谱、热重、原子力显微镜和DFT理论计算等方法对二氧化锡和伽马氧化铝表面结构进行了初步探究。得到以下结果：1.通过水热方法制备了超薄的Sn02纳米片。研究了水热时间对产物的影响；不同温度热处理和羟基化Sn02纳米片的119Sn MAS NMR的数据与DFT理论计算结果相结合,能够区分Sn02纳米片表面几种不同的Sn物种,显示借助固体核磁共振可以定量分析金属氧化物表面原子的比例；2.在MgGa2O4表面借助原子层沉积了单层A1203。通过27Al1H MAS NMR与XRD相结合,研究了煅烧温度对上述体系表面A1结构的影响。随着煅烧温度的升高,同质量Al2O3/MgGa2O4的27 Al MAS NMR信号强度逐渐减小,其原因可能是热处理改变了不同化学环境A1的构型对称性,导致相应四极耦合常数(CQ)变大使得谱峰展宽而难以观测。
[Abstract]:In recent years, nanometallic oxides have shown great potential in the fields of energy, catalysis, environment and biology. The surface structure of nanomaterials is closely related to their properties, so it is necessary to master these structural information at the atomic and molecular levels. Solid nuclear magnetic resonance (SNMR) is a powerful tool for the study of short range and intermediate range order of solid materials. It can be used for the analysis of specific elements (atomic nuclei). It has the characteristics of preserving the original phase of the sample, no damage detection and quantitative research. In this paper, solid nuclear magnetic resonance (SNMR) method is the core, supplemented by X-ray diffraction, transmission electron microscope, Fourier transform infrared spectroscopy, thermogravimetry. The surface structures of tin dioxide and gamma alumina were investigated by atomic force microscope and DFT theory. Get the following result: 1. Ultrathin Sn02 nanoparticles were prepared by hydrothermal method. The influence of hydrothermal time on the product was studied, and the 119Sn MAS NMR data of Sn02 nanocrystals at different temperatures and hydroxylation were combined with the DFT theory to distinguish several different Sn species on the surface of Sn02 nanoparticles. It is shown that the ratio of metal oxide surface atoms can be quantitatively analyzed by solid nuclear magnetic resonance. Monolayer A1203 was deposited on MgGa2O4 surface by atomic layer. The effect of calcination temperature on the surface A1 structure of the system was studied by means of 27Al1H MAS NMR and XRD. With the increase of calcination temperature, the 27Al MAS NMR signal intensity of Al _ 2O _ 3 / MgGa _ 2O _ 4 of the same mass decreases gradually, which may be due to the heat treatment changing the symmetry of A1 configuration in different chemical environments. As a result, the corresponding quadrupole coupling constant (CQ) becomes larger and the spectral peaks are widened and difficult to observe.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ134.32;TQ133.1;TB383.1

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