纳米线阵列的宽光谱修饰及其多带隙制氢

发布时间：2018-05-18 11:05

  本文选题：纳米线阵列 + Type-Ⅱ型能带结构　； 参考：《湘潭大学》2015年硕士论文

【摘要】：近年来,越来越多的人开始研究新型的太阳能转换设备,纳米材料和纳米结构的引入对其性能的提高展现了至关重要的作用。许多一维纳米结构被用于光伏器件的制备,这些结构中最为常见的有纳米线和纳米管。这是因为它们理想的几何结构能够为电子的输运提供直接通道。相比于薄膜材料,一维纳米材料在可以光光谱范围内对光有更低的反射率,因而具有更优良的光吸收特性。ZnO纳米线阵列因其温和的合成方法和优越的光学性质被大量用于光伏器件。然而,Zn O的带隙比较大(室温下E=3.37eV),不能够有效的吸收和利用太阳光可见光区域的能量。为了通过可见光激发生成更多的电子-空穴对,很多研究将窄带隙的材料负载在ZnO纳米线上,在这些敏化材料中,CdS和CdSe是最常用的两种可见光敏化半导体。在本文中,我们主要以ZnO和TiO2/ZnO纳米线阵列为基础,通过具有不同带隙的硫属化合物(如ZnSe,CdS和CdSe)将其多重敏化,以提高复合电极材料可见光区的光吸收能力,最后达到促进其光电化学制氢性能的效果。论文的主要内容如下:1.首先,我们使用水热法、离子交换方法以及连续的化学浴沉积方法在FTO导电玻璃基底上合成ZnSe/CdS/CdSe三重敏化的ZnO纳米线阵列结构用于多带隙制氢。离子交换方法和化学浴沉积方法能够很好地控制敏化层的厚度,这些敏化层的厚度将直接影响所合成异质结构的可见光吸收能力以及它们的光电化学性能。实验发现,通过ZnO纳米线阵列和各敏化层之间的协同光吸收作用以及它们之间连续阶梯式type-Ⅱ型能带结构排列,我们制备出来的ZnO@ZnSe/CdS/CdSe复合阵列光电极的光电化学制氢性能相对简单的ZnO纳米线阵列以及其它复合光电极(如:ZnO@ZnSe和ZnO@ZnSe/CdS)有不同程度的提高。当测试偏压为0V时(vs.Ag/AlCl),ZnO@ZnSe/CdS/CdSe纳米线阵列光电极的饱和光电流密度达到5.3 mA/cm2,远大于ZnO@ZnSe(1.1 mA/cm2)和ZnO@ZnSe/CdS(2.6 mA/cm2)纳米线阵列光电极的电流密度,是纯ZnO纳米线阵列光电极电流密度大小的12倍。2.另外,在FTO导电玻璃上合成CdS/CdSe共敏化的叠层TiO2/ZnO纳米线阵列,并用于光电化学制氢。具体过程是,先在FTO上通过水热法生长TiO2纳米线阵列,随后以其为基底再生长一层ZnO纳米线阵列。为了进一步提高TiO2/ZnO的可见光吸收能力,我们依次通过窄带隙的CdS和CdSe量子点将其敏化。光电化学性能测试结果发现,当测试偏压为0V时(vs.Ag/AlCl),TiO2/ZnO@CdS/CdSe纳米线阵列光电极的光电流密度达到了9.8 mA/cm2,是TiO2/ZnO@CdS纳米线阵列的1.5倍。此外,在偏压为0.6V时(vs.Ag/AlCl),TiO2/ZnO@CdS/CdSe纳米线阵列光电极的饱和光电流密度达到11.5 mA/cm2。
[Abstract]:In recent years, more and more people began to study new solar energy conversion equipment. The introduction of nano-materials and nanostructures has shown a crucial role in improving their performance. Many one-dimensional nanostructures are used to fabricate photovoltaic devices, the most common of which are nanowires and nanotubes. This is because their ideal geometry can provide direct channels for the transport of electrons. Compared with thin film materials, one-dimensional nanomaterials have lower reflectivity to light in the range of light spectrum. ZnO nanowire arrays are widely used in photovoltaic devices because of their mild synthesis methods and superior optical properties. However, the band gap of Zno is relatively large (E ~ (3. 37) EV ~ (2 +) at room temperature, which can not effectively absorb and utilize the energy in the visible region of solar light. In order to generate more electron-hole pairs by excitation of visible light, many studies have carried narrow band gap materials onto ZnO nanowires. Among these sensitized materials, CDs and CdSe are the two most commonly used visible Guang Min semiconductors. In this paper, we mainly use ZnO and TiO2/ZnO nanowire arrays as the basis to increase the optical absorption ability of the composite electrode materials in the visible region by the multiple sensitization of sulfur compounds with different band gaps (such as ZnSee, CDs and CdSee). Finally, the effect of promoting its photochemical hydrogen production performance is achieved. The main contents of the thesis are as follows: 1: 1. Firstly, ZnSe/CdS/CdSe triple sensitized ZnO nanowire arrays were synthesized on FTO conductive glass substrate by hydrothermal method, ion exchange method and continuous chemical bath deposition method. Ion exchange method and chemical bath deposition method can control the thickness of the sensitized layer. The thickness of these sensitized layers will directly affect the visible light absorption ability of the synthesized heterostructures and their photochemical properties. The experimental results show that the ZnO nanowire array and the sensitized layers have synergistic optical absorption, and the continuous type 鈪，

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