磷酸铋系列光催化剂的合成及其在水中亚硝酸盐光催化转化中的应用

发布时间：2018-05-01 11:27

本文选题：光催化转化NO_2~- + 上转换发光材料　；参考：《辽宁大学》2017年硕士论文

【摘要】：在现代工业和农业生产过程中,由于含氮化合物的大量使用,使得水体中亚硝酸盐的浓度显著上升。亚硝酸盐是一种对人体健康有很大毒性的无机环境污染物。为了满足健康需求,去除饮用水中的亚硝酸盐十分必要。近年来,光催化技术因其能直接利用吸收的光去除水体中污染物并且易分离回用而受到了广泛的关注。这种方法是简单并且对于环境友好的,而且能够利用清洁、丰富和易得到的太阳能源。通过调查,磷酸铋作为一种新型非金属含氧酸根半导体,非常适合用于亚硝酸盐的转化。然而研究中发现,有两个因素严重限制了磷酸铋的催化活性,一是作为一个宽带半导体,磷酸铋吸收的太阳光的能力很差,只能利用紫外光来获得光子能源,而紫外光只占太阳光谱的5%。因此,如何充分有效的利用太阳光,是我们亟待解决的问题。二是半导体本身过高的光生电子-空穴复合率,抑制了半导体材料的催化活性。如何有效的抑制光生电子-空穴复合,也是亟待解决的难题。因此,本文采用水热法、溶胶凝胶法、超声分散、沸液法、沉积沉淀法、高温煅烧法分别制备了Er~(3+):Y_3Al_5O_(12)/BiPO_4和Er~(3+):YAlO_3@(PdS/BiPO_4)/(Au/rGO)/CdS,形成了两种复合模拟太阳光催化体系。通过上转换发光材料,将太阳光中波长较长的可见光及部分红外光转换成能够被宽带半导体直接利用的紫外光,从而拓宽宽带半导体的光响应范围,提高太阳光利用率。另一方面,为解决光生电子-空穴对复合的问题,我们采用在光催化体系中使用窄带半导体复合、添加助催剂及构建电子通路的方法,来抑制光生电子-空穴对的复合,从而提高催化剂体系的活性。本论文通过X-射线衍射(XRD)、扫描电子显微镜(SEM)、透射电镜(TEM)、能量色散X射线光谱(EDX)、X-射线光电子能谱(XPS)、傅里叶转换红外光谱(FT-IR)和拉曼光谱(Raman)对上述催化剂的表面形态,晶体类型以及化学组成进行表征。通过紫外可见漫反射光谱(UV-DRS)及光致发光光谱(PL)讨论了上转换发光材料Er~(3+):Y_3Al_5O_(12)和Er~(3+):YAlO_3的发光特性。并利用光致发光光谱(PL)讨论了复合后的模拟太阳光催化体系光生电子-空穴的复合问题。此外,我们还评价了不同光源、光照时间、电子空穴牺牲剂、循环使用次数等因素对两种光催化体系光催化转化NO_2~-的活性及效果的影响。通过对两种光催化剂体系的研究,我们发现,上转换发光材料与宽带半导体复合可以拓宽光催化体系的光响应范围,而复合窄带半导体、添加助催剂及构建电子通路则可以通过抑制光生电子-空穴复合来增强体系的光催化活性。本研究为将来利用太阳光催化转化亚硝酸盐及其他环境污染物提供了一种新的途径。
[Abstract]:In the process of modern industrial and agricultural production, nitrite concentrations in water increased significantly due to the extensive use of nitrogenous compounds. Nitrite is a kind of inorganic environmental pollutant which has great toxicity to human health. It is necessary to remove nitrite from drinking water in order to meet health needs. In recent years, photocatalytic technology has attracted wide attention because of its ability to remove pollutants from water bodies directly and to separate and reuse them easily. This approach is simple and environmentally friendly, and can take advantage of clean, rich and readily available solar energy. Bismuth phosphate is a new type of nonmetallic oxygenate semiconductor, which is suitable for nitrite conversion. However, there are two factors that severely limit the catalytic activity of bismuth phosphate. One is that as a broadband semiconductor, bismuth phosphate absorbs very poor solar light and can only use ultraviolet light to obtain photonic energy. Ultraviolet light accounts for only 5% of the solar spectrum. Therefore, how to make full and effective use of sunlight is an urgent problem to be solved. The other is that the photoelectron-hole recombination rate of the semiconductor itself is too high, which inhibits the catalytic activity of the semiconductor material. How to effectively suppress photogenerated electron-hole recombination is also a difficult problem to be solved. Therefore, in this paper, hydrothermal method, sol-gel method, ultrasonic dispersion, boiling liquid method, deposition precipitation method and high-temperature calcination method were used to prepare Er~(3: Y3Al5O-, respectively, Er~(3: Y3Al5O- (12 / BiSP) and Er~(3: YAlO3DS-P / BiPO4 / BiPO4 / GOrGO- CdSs, respectively, to form two kinds of complex simulated solar photocatalytic systems. Through up-conversion luminescent materials, the visible light and some infrared light in the solar light with longer wavelength can be converted into ultraviolet light which can be directly used by broadband semiconductor, thus widening the range of light response of broadband semiconductor and improving the utilization ratio of solar light. On the other hand, in order to solve the problem of photogenerated electron-hole pair recombination, we use narrow-band semiconductor recombination in photocatalytic system, add accelerator and construct electron pathway to restrain photogenerated electron-hole pair recombination. Thus, the activity of the catalyst system was improved. In this paper, the surface morphology of the catalysts was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy (Raman). The crystal type and chemical composition were characterized. The luminescence properties of up-conversion luminescent materials Er~(3: Y3AlS5O / S and Er~(3 / YAlO3 were discussed by UV-DRS and photoluminescence spectra. The photoluminescence spectroscopy (PLL) was used to discuss the photo-electron-hole recombination of the simulated photocatalytic system. In addition, we also evaluated the effects of different light sources, illumination time, electron hole sacrificial agent and times of recycling on the photocatalytic activity and effect of two photocatalytic systems for the conversion of NO2-. Through the study of two kinds of photocatalyst systems, we found that the combination of up-conversion luminescent material and wide-band semiconductor can widen the photoresponse range of photocatalytic system, and compound narrow-band semiconductor. The photocatalytic activity of the system can be enhanced by inhibiting the photogenerated electron-hole composite by adding the catalyst and constructing the electronic pathway. This study provides a new way to catalyze the conversion of nitrite and other environmental pollutants by solar light in the future.
【学位授予单位】：辽宁大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;O644.1;R123

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