基于二氧化钛空心复合材料的制备及其光催化性能研究

发布时间：2018-05-05 08:20

本文选题：二氧化钛 + 空心球　；参考：《扬州大学》2017年博士论文

【摘要】：21世纪,环境污染和能源匮乏是人类社会面临的亟待解决的重大问题。半导体光催化技术在利用太阳能和解决环境污染方面有着广泛的应用前景。在众多氧化物半导体光催化材料中,二氧化钛(TiO2)半导体光催化材料以无毒、价廉、稳定性好和光催化活性高等优点被广泛应用于污水处理、空气净化、抗菌、自清洁材料和分解水制氢等领域。但是半导体二氧化钛禁带宽度较宽,只能吸收太阳光中的紫外光部分,同时由于光催化过程中二氧化钛表面光生电子-空穴对的快速重组使量子效率较低,严重阻碍了二氧化钛在实际生活中的应用。针对上述难题,本论文以具有高比表面积及渗透性良好的二氧化钛空心球为基材,通过结构调控、复合改性、掺杂等方法提高二氧化钛光吸收范围及减缓光催化反应过程中光生电子-空穴对的复合速率增强其光催化活性。主要研究内容如下:1.r-GO/Au/TiO2三明治结构空心复合材料以氨基修饰的二氧化硅(SiO2)微球为模板,通过静电作用及溶胶法在其表面依次包裹氧化石墨烯(GO)、金纳米粒子(Au)及TiO2层,最后除去模板并高温煅烧得到具有高比表面积且可见光响应的夹层状r-GO/Au/TiO2空心复合材料。通过TEM、XRD、STEM、EDS mapping和N2吸附-脱附等方法对r-GO/Au/TiO2空心复合材料进行表征。通过在紫外光、可见光及模拟日光照射下降解有机染料罗丹明B、亚甲基蓝和甲基橙来评价所制备的空心复合材料的光催化性能。光催化性能研究结果表明r-GO/Au/TiO2复合催化剂在可见光及模拟日光下罗丹明B降解动力学常数分别达到了 0.012和0.029 min-1,与r-GO/TiO2催化剂相比(k=0.0023和0.017 min-1)分别提高了 4.3和0.75倍。可见光及模拟日光下降解亚甲基蓝、甲基橙也表现出较好的光催化活性。2.Au@r-GO/TiO2蛋黄-蛋壳结构复合材料在上章研究的基础上,通过结构优化,减少贵金属的用量,以Au@SiO2为模板,表面氨基修饰,在其表面包裹氧化石墨烯(GO)和TiO2层,最后经过高温煅烧和碱蚀刻除去模板得到比表面积大、可见光响应的三元Au@r-GO/TiO2空心复合材料。通过TEM、XRD、HRTEM、EDS mapping、N2吸附-脱附及UV-Vis光谱等对Au@r-GO/TiO2空心复合材料进行表征。光催化活性研究结果表明,与Ti02、r-GO/TiO2和Au@TiO2相比,所制备的蛋黄-蛋壳结构Au@r-GO/TiO2复合催化剂在可见光及模拟日光下降解罗丹明B和光解水产氢中表现出更优越的光催化活性。3.TiO2/NiO空心复合材料贵金属由于价格昂贵,进一步通过与半导体氧化镍(NiO)复合制备非贵金属复合催化剂来提高TiO2的光催化性能。以SiO2微球为模板,在SiO2表面依次包裹TiO2和NiO,高温煅烧后碱蚀刻除去模板得到可见光响应的TiO2/NiO空心复合材料。通过TEM、HRTEM、XRD、UV-Vis、N2吸附-脱附及时间分辨荧光等方法对TiO2/NiO空心复合材料进行表征。研究结果表明,空心复合材料的组成和形貌主要取决于反应物浓度。材料表征发现与NiO复合之后空心复合材料的比表面积显著提高,从纯TiO2空心球的90.3 m2 g-1提高至114-180 m2g-1。所制备的TiO2/NiO空心复合材料与同条件下制备的TiO2空心球相比具有更高的光催化活性,当NiO含量为3.4 wt%时,TiO2/NiO复合催化剂在光催化降解有机污染物及光解水产氢中表现出最好的光催化性能。4.NiO/TiO2/C空心复合材料由于金属氧化物半导体内在导电性差的缺点阻碍了光催化反应过程中复合材料内部电子的有效转移,因此异质结光催化剂的光催化性能有待进一步提升。以聚苯乙烯(PS)微球替代SiO2微球为模板,以同样的实验条件包裹TiO2和NiO,最后通过煅烧过程制得NiO/TiO2/C介孔空心复合材料。通过TEM、HRTEM、XRD、UV-Vis和N2吸附-脱附等方法对NiO/TiO2/C空心复合材料进行表征。PS微球起到了双功能作用,不仅作为制备空心结构的模板还作为石墨化碳源。光催化降解有机污染物及光催化产氢活性研究结果表明NiO/TiO2/C(800℃)表现出最好的可见光光催化性能。与TiO2/NiO相比,石墨化碳的引入使得复合材料的光催化性能得到了进一步的提升,光催化产氢速率(356 μmol h-1 g-1)与TiO2/NiO 相比提升了近一倍(180 μmol h-1 g-1)。5.C/N-TiO2空心复合材料非金属元素掺杂提高Ti02光催化活性的有效途径。以聚苯胺(PANI)为C/N掺杂源,PS/PANI为模板成功制备C/N-TiO2介孔空心复合材料。通过TEM、XRD、STEM、EDS mapping和N2吸附-脱附等方法对C/N-TiO2介孔空心复合材料进行表征。C/N共掺杂通过C、N2p轨道与O 2p轨道杂化可降低TiO2的禁带宽度,使掺杂后的TiO2光响应吸收边拓展到可见光的区域。与TiO2(600)空心球及C-TiO2(600)空心复合材料相比,可见光下光催化降解有机染料罗丹明B、苯酚及光分解水产氢研究结果表明碳氮共掺杂可显著提高Ti02的可见光光催化性能。C/N-TiO2(600)空心复合材料的光催化活性最高,光催化降解罗丹明B及苯酚的动力学速率常数分别为0.022及0.012 min-1;光催化分解水产氢速率达到最高为291μmolh-1g-1,对应的表观量子效率为0.9%。C/N-TiO2空心复合材料表现出的优异光催化性能表明其可作为潜在的低成本且性能好的可见光催化剂。
[Abstract]:In twenty-first Century, environmental pollution and energy shortage are the major problems to be solved in human society. Semiconductor photocatalytic technology has a wide application prospect in the use of solar energy and environmental pollution. In many oxide semiconductor photocatalytic materials, titanium dioxide (TiO2) semiconductor photocatalytic materials are non-toxic, inexpensive and stable. The advantages of good and photocatalytic activity are widely used in the fields of sewage treatment, air purification, antibacterial, self cleaning materials and hydrogen production by decomposing water. However, the band gap of semiconductor titanium dioxide is wide, only absorption of ultraviolet light in the light of the sun, and the rapid weight of the photoelectron hole pair on the surface of titanium dioxide during the photocatalytic process. In this paper, the titanium dioxide hollow sphere with high specific surface area and good permeability is used as the substrate to improve the optical absorption range of two titanium oxide and to slow down the photocatalytic reaction process. The photocatalytic activity of the photogenerated electron hole pair is enhanced. The main contents are as follows: the 1.r-GO/Au/TiO2 sandwich structure hollow composite material with amino modified silica (SiO2) microspheres is a template, which is sequentially encapsulated graphene (GO), gold nanoparticles (Au) and TiO2 layer on its surface by electrostatic action and sol-gel method. The sandwich r-GO/Au/TiO2 hollow composite materials with high specific surface area and visible light response were obtained with high surface area and high temperature calcined. R-GO/Au/TiO2 hollow composite materials were characterized by TEM, XRD, STEM, EDS mapping and N2 adsorption desorption. The degradation of organic dye Luo Danming B by UV, visible light and simulated sunlight. The photocatalytic properties of the prepared hollow composites were evaluated by methyl blue and methyl orange. The results of photocatalytic performance showed that the degradation kinetics constants of r-GO/Au/TiO2 composite catalysts were 0.012 and 0.029 min-1 respectively in visible light and simulated daylight, respectively, and compared with r-GO/TiO2 catalysts (k=0.0023 and 0.017 min-1), respectively. 4.3 and 0.75 times. Visible light and simulated sunlight degradation of methylene blue, methyl orange also showed good photocatalytic activity.2.Au@r-GO/TiO2 egg yolk structure composite material based on the study of the upper chapter, through structure optimization, reduce the amount of precious metals, Au@SiO2 as a template, surface amino modification, the surface of the coated graphene oxide (GO) and TiO2 layer, the three element Au@r-GO/TiO2 hollow composite materials with large specific surface area and visible light response were obtained by high temperature calcination and alkali etching. TEM, XRD, HRTEM, EDS mapping, N2 adsorption desorption and UV-Vis spectra were used to characterize Au@r-GO/TiO2 hollow composites. Compared with iO2 and Au@TiO2, the prepared egg yolk Eggshell Structure Au@r-GO/TiO2 composite catalyst exhibits superior photocatalytic activity.3.TiO2/NiO hollow composites in the degradation of Luo Danming B and the photolysis of aquatic hydrogen under the visible light and the simulated sunlight. Metal composite catalysts are used to improve the photocatalytic performance of TiO2. Using SiO2 microspheres as a template, TiO2 and NiO are encapsulated on the SiO2 surface, and TiO2/NiO hollow composite materials with visible light response are obtained by alkali etching after calcining at high temperature. Through TEM, HRTEM, XRD, UV-Vis, N2 adsorption desorption and time resolved fluorescence, the hollow composite material of the TiO2/NiO is used. The results show that the composition and morphology of the hollow composite depend mainly on the concentration of the reactant. The material characterization shows that the specific surface area of the hollow composite material is significantly improved after the composite of NiO, and the TiO2/NiO hollow composites prepared from 90.3 M2 g-1 of pure TiO2 hollow sphere to 114-180 m2g-1. are prepared and prepared under the same condition. The photocatalytic activity of TiO2 hollow spheres is higher than that of the hollow spheres. When the content of NiO is 3.4 wt%, the TiO2/NiO composite catalyst shows the best photocatalytic performance in the photocatalytic degradation of organic pollutants and the photolysis of aquatic hydrogen. The.4.NiO/TiO2/C hollow composite has hindered the photocatalytic reaction due to the poor internal conductivity of the metal oxide semiconductor. In the process of the effective transfer of the internal electrons in the composite material, the photocatalytic performance of the heterojunction photocatalyst needs to be further enhanced. The PS microspheres are substituted for the SiO2 microspheres as a template and the TiO2 and NiO are wrapped in the same experimental conditions. Finally, the NiO/ TiO2/C mesoporous hollow composites are prepared through the calcination process. Through TEM, HRTEM, XRD, UV-. Vis and N2 adsorption desorption methods have played a dual function on the characterization of.PS microspheres by NiO/TiO2/C hollow composite materials, not only as a template for the preparation of hollow structures, but also as a graphite carbon source. The results of photocatalytic degradation of organic pollutants and photocatalytic hydrogen production show that NiO/TiO2/C (800 C) shows the best visible light photocatalysis. Performance. Compared with TiO2/NiO, the introduction of graphitized carbon makes the photocatalytic properties of the composites further improved, and the rate of photocatalytic hydrogen production (356 Mu mol H-1 g-1) increases nearly one times (180 Mu mol H-1 g-1), which is an effective way to improve the photocatalytic activity of Ti02 by doping nonmetallic elements of.5.C/N-TiO2 hollow composites. Using polyaniline (PANI) as a C/N doping source and PS/PANI as a template, C/N-TiO2 mesoporous hollow composites are prepared successfully. By means of TEM, XRD, STEM, EDS mapping and N2 adsorption and desorption, C/N-TiO2 mesoporous hollow composite materials are characterized by CO doping. Compared with TiO2 (600) hollow spheres and C-TiO2 (600) hollow composite materials, the photocatalytic degradation of organic dye Luo Danming B, phenol and photodecomposition of aquatic hydrogen show that CO doping of carbon and nitrogen can significantly improve the visible light photocatalytic properties of.C/N-TiO2 (600) hollow composite materials of Ti02. The kinetic rate constants of photocatalytic degradation of Luo Danming B and phenol are 0.022 and 0.012 min-1, respectively, and the rate of photocatalytic decomposition of aquatic hydrogen is up to 291 mu molh-1g-1, and the apparent quantum efficiency of the corresponding 0.9%.C/N-TiO2 hollow composite shows that it can be used as a potential low cost and low cost. Good performance visible light catalyst.

【学位授予单位】：扬州大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O643.36

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