基于液相沉积技术制备的金属氧化物膜及其可见光电催化性能研究

发布时间：2018-05-03 11:56

  本文选题：液相沉积 + 可见光　； 参考：《华中科技大学》2015年博士论文

【摘要】：光电催化技术是处理环境中有机污染物的重要的高级氧化技术之一,其中,光阳极材料的性能是影响光电催化系统效率的一个关键因素。在制备光阳极膜的方法中,液相沉积法具有制备过程简单、成本低、基体适用范围广等优点。本论文研究利用液相沉积法分别制备了ZnO薄膜、Ag/ZnO复合薄膜、α-Fe2O3薄膜和WO3/TiO2薄膜,通过X-射线衍射(XRD)、扫描电镜(SEM)、X射线能谱(EDX)、X-射线光电子能谱(XPS)和紫外-可见漫反射(UV-Vis DRS)等多种手段对薄膜的材料学和光学性能进行了表征分析,并将这些薄膜电极用于可见光光照下光电催化降解有机污染物。论文的主要研究内容如下：(1)发展了一种新型的以ZnO-HF和H3BO3为前驱体的的液相沉积法制备ZnO薄膜,并通过罗丹明B(RhB)和对硝基酚(PNP)的降解研究了膜电极在可见光照射下的光电催化性能。结果表明,ZnO薄膜为表面不规则的纳米棒状,在可见光区域有一定的吸收。通过调节前驱液中ZnO和H3B03的比例可以改变ZnO膜电极的可见光电催化性能,当ZnO和H3B03的摩尔比为1：2时,薄膜的光电催化活性最高,在240 min内可以降解43.3%的RhB,在210 min内可将75.1%的PNP降解。(2)采用液相沉积法结合紫外光还原法制备了负载纳米Ag的ZnO薄膜电极。SEM[和XPS分析表明纳米Ag颗粒分布在ZnO纳米棒上,且沉积量随着光还原时间的加长而增加。相比纯的ZnO电极,Ag/ZnO复合薄膜的光电催化效率均有所提高。其中,在紫外光照射3min后得到的复合膜电极光电催化活性最高,在可见光照射并外加0.8 V偏压时,在240 min内对RhB的降解率可达到61.3%,比单纯ZnO薄膜的降解率高了18%。膜电极的光电催化活性的提高主要是由于Ag的负载可以提高ZnO薄膜对可见光的利用率,同时Ag与ZnO之间的肖特基势垒有助于光生电子-空穴对的分离。(3)以FeOOH-NH4FHF和H3B03为前驱体,通过液相沉积过程制备了α-Fe2O3薄膜,并研究了该膜电极在可见光照射下的光电催化性能。结果表明,经600℃焙烧后的α-Fe2O3薄膜表面为多孔状结构,禁带宽度大约为2.0 eV,相比其它温度下焙烧后的膜电极此薄膜光电催化活性最高。在此电极上,经光电催化反应后,甲基橙(MO)在120min内的降解率达到79.1%,对硝基酚(PNP)在240min内的降解率为46.8%。此LPD α-Fe2O3薄膜具有良好的可见光电催化性能和稳定性。(4)采用两步液相沉积法制备了WO3/TiO2薄膜电极。SEM的分析和FTO上不同膜沉积量的测定表明底层的TiO2由纳米颗粒组成,上层的WO3呈现由纳米片交叉聚集形成的花状结构,而且TiO2薄膜为WO3的沉积提供了一个良好的基底。同时,WO3明显增加了TiO2对可见光的吸收,提高了TiO2薄膜的可见光电催化活性。当WO3前驱液中H3BO3浓度为0.2 mmol·L-1时,得到的WO3/TiO2薄膜具有最好的光电催化性能,在可见光照射下,同时施加1.0 V的阳极偏压,对RhB的降解率在240min内可以达到50.9%,对4-氯苯酚(4-CP)的降解率在90 min内能够达到大约80%。此液相沉积W03/TiO2薄膜具有高效的光电催化活性和稳定性,适于降解多种难降解有机污染物。
[Abstract]:Photoelectrochemical technology is one of the most important advanced oxidation technologies for the treatment of organic pollutants in the environment. The performance of the photoanode material is a key factor affecting the efficiency of the photoelectric catalytic system. In the preparation of the photoanode film, the liquid phase deposition has the advantages of simple preparation process, low cost and wide application range. The material and optical properties of ZnO film, Ag/ZnO composite film, alpha -Fe2O3 film and WO3/TiO2 film were prepared by liquid phase deposition, respectively by X- ray diffraction (XRD), scanning electron microscopy (SEM), X ray energy spectrum (EDX), X- ray photoelectron spectroscopy (XPS) and UV visible diffuse reflectance (UV-Vis). The main research contents of this paper are as follows: (1) a new type of liquid phase deposition method with ZnO-HF and H3BO3 as precursors was developed to prepare ZnO thin films, and the film electrode was studied by the degradation of Luo Danming B (RhB) and p-nitrophenol (PNP). The results show that the ZnO film is an irregular nanoscale rod with a certain absorption in the visible light region. The visible Photoelectrochemical Performance of the ZnO film electrode can be changed by adjusting the ratio of ZnO and H3B03 in the precursor. When the molar ratio of ZnO and H3B03 is 1:2, the photocatalytic activity of the film is the highest, at 2 In 40 min, 43.3% of RhB can be degraded and 75.1% PNP can be degraded in 210 min. (2).SEM[and XPS of ZnO thin film electrodes loaded with nano Ag are prepared by liquid deposition and UV reduction method. The distribution of nano Ag particles on ZnO nanorods, and the amount of deposition increases with the lengthening of the light return time. The photoelectric catalytic efficiency of the nO composite film is improved. The photoelectrochemical activity of the composite membrane electrode obtained by UV irradiation for 3min is the highest. The degradation rate of RhB can reach 61.3% in 240 min when visible light is irradiated with 0.8 V, and the photocatalytic activity of 18%. film electrode is higher than that of pure ZnO film. The main reason is that the Ag load can improve the utilization of visible light in the ZnO film, and the Schottky barrier between Ag and ZnO helps to separate the photoelectron hole pair. (3) the precursor of FeOOH-NH4FHF and H3B03 is used as the precursor to prepare the alpha -Fe2O3 film through the liquid phase deposition process, and the photoelectrochemical catalysis of the membrane electrode under visible light is studied. The results show that the surface of the alpha -Fe2O3 film after calcination at 600 C is a porous structure, and the band gap is about 2 eV, and the photo catalytic activity of this film is the highest compared with that of the film electrode prepared at other temperatures. On this electrode, the degradation rate of methyl orange (MO) in 120min is 79.1%, and p-nitrophenol (PNP) in 240mi at this electrode. The degradation rate within n is 46.8%., the LPD alpha -Fe2O3 film has good visible photo catalytic performance and stability. (4) the analysis of WO3/TiO2 thin film electrode.SEM and the determination of the deposition of different films on FTO show that the TiO2 of the bottom is composed of nanoparticles and the WO3 in the upper layer is formed by the cross aggregation of nanoscale. The flower structure and the TiO2 film provide a good substrate for the deposition of WO3. At the same time, WO3 obviously increases the absorption of visible light by TiO2 and improves the visible photo catalytic activity of the TiO2 film. When the H3BO3 concentration is 0.2 mmol. L-1 in the WO3 precursor, the obtained WO3/TiO2 films have the best Photoelectrochemical Performance, and the visible light irradiation is shown in the visible light. At the same time, the anodic bias of 1 V was applied, the degradation rate of RhB could reach 50.9% in 240Min, and the degradation rate of 4- chlorophenol (4-CP) in 90 min could reach about 80%.. The photocatalytic activity and stability of the liquid phase deposited W03/TiO2 film were high, and it was suitable for the degradation of many kinds of refractory organic pollutants.

【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB383.2;X505

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