摘要/Abstract

二维纳米结构二氧化钛由于表面活性位点剧增可带来光催化活性的显著提高.本文通过液相法在低温条件下合成大尺寸TiO₂纳米片，重点研究溶液中硝酸浓度、熟化温度和反应物浓度对其二维结构形成过程的影响.采用透射电子显微镜（TEM）表征样品的微观形态，并结合紫外-可见吸收光谱、X射线衍射谱（XRD）、X射线光电子能谱（XPS）和傅立叶变换红外光谱分析样品的微结构性质.采用光催化还原Cr （VI）作为指示反应，评估各制备参数对二氧化钛光催化性能的影响.结果表明，硝酸浓度为0.0217~0.0721 mol·L^-1的样品在0~4℃条件下胶溶及熟化时可得到具有显著量子尺寸效应的超薄锐钛矿型TiO₂纳米片；硝酸浓度过高引起样品晶型和形态的转变，过低导致胶溶时间延长；熟化温度超过4℃会破坏二维结构的形成；提高反应物中乙醇的用量有助于分散水解产物，促进胶溶和二维结构的形成进程.
关键词: TiO₂团簇, TiO₂纳米片, 低温合成, 影响因素, 光催化活性
Synthesis of large scale ultrathin 2D structural TiO₂ is challenging and meaningful in many fields of science and technology, because of their larger surface area and higher electron-hole pairs separation efficiency. In this work, a "bottomup" method is used to synthesize the large-size ultrathin TiO₂ nanosheets at low temperature by liquid-phase. The mixture of tetrabutyl titanate and ethanol could hydrolyze in a dilute nitric acid solution with an ice-water bath and the obtained hydrolysates could peptize. After peptized, the hydrolysis products become to be very small TiO₂ nanoclusters and they form a two-dimensional network structure via the orientation bonding formed by hydrogen bond. Continue to be aged at low temperature, the crystallization degree of samples will increase, and the networks eventually turn into TiO₂ nanosheets. Effects of the concentration of nitric acid, ambient temperature and reactant concentration on the formation of two-dimensional structure TiO₂ are studied in this work. The transmission electron microscope (TEM), ultraviolet-visible (UV-Vis) absorbance spectra, X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy (FTIR) are used to analyze the morphology, microstructure and properties of the samples, and the experiment of photocatalytic reduction of Cr(VI) is conducted to observe the photocatalytic activity of samples as well as to verify the effects of system parameters on the microstructure of TiO₂ nanosheets. The results show that when the concentration of nitric acid is during 0.0217~0.0721 mol·L^-1, the anatase TiO₂ nanosheets that thinner than 1 nm could be obtained by peptizing and aging at 0~4℃. Excess nitric acid leads to crystalline and morphology transformation of TiO₂, but lower concentration of nitric acid could prolong the peptizing time; increasing the ambient temperature will undermine the formation of two-dimensional structure; improving the amount of ethanol in the reactant will be helpful to disperse the hydrolysis products, and promote the process of the peptizing and formation of the two-dimensional structure.
Key words: TiO₂ clusters, TiO₂ nanosheets, low temperature synthesis, influence factors, photocatalytic activity


PDF全文下载地址:

点我下载PDF