染料敏化的氧化锌“纳米草坪”的构建及其光催化制氢性能

发布时间：2019-02-17 10:09

【摘要】：众所周知,氢气被认为是未来最理想的能源载体。因而,光催化水制氢成为了目前太阳能储存和转换领域中的重要课题。在众多的光催化剂中,氧化锌因其具有与二氧化钛相似的能带结构和光电性质、电子迁移率高、易于结晶和各向异性生长等特点被认为是一种有前途的光催化剂,有望在太阳能转换和光催化制氢领域中得到广泛应用。特别是,具有高长径比的氧化锌纳米结构因其具有较颗粒状纳米氧化锌更为优异的电子传输性能和更大的比表面积等特点更加引入注目。然而氧化锌是一个宽带隙半导体,只在紫外光区有吸收,这限制了其实际应用。目前的研究表明,染料敏化被认为是拓宽光催化剂工作波长的最有效的方法之一因而,染料敏化的、具有高长径比的氧化锌纳米结构有可能是一个高效的可见光催化剂。并且利用它可能解决纳米材料固定化所带来的问题,如比表面积下降、光催化活性降低等。基于以上思路,本文构建了一系列染料敏化的氧化锌纳米棒阵列(“纳米草坪”),并对该催化体系的光催化制氢活性进行了较为系统的探索。主要内容如下：(1)对氧化锌“纳米草坪”的低温水热制备技术进行了系统的研究。探讨了水热温度、水热时间、前驱体浓度等因素对氧化锌“纳米草坪”的形貌、晶体结构等的影响。最终制得了具有高长径比的,结构均一且稳定的氧化锌“纳米草坪”。(2)使用曙红Y作为敏化剂,构建了曙红Y敏化的氧化锌“纳米草坪”。在此基础上,以三乙醇胺(TEOA)作为牺牲剂,可见光的照射下,考察了曙红Y敏化的氧化锌“纳米草坪”的光催化制氢活性。同时通过光谱学手段和光电化学手段对染料特性和制氢机理进行了初步研究。实验结果表明,该复合催化体系具有较高的可见光催化活性,是一种高效的可见光催化制氢催化剂。其最大制氢速率达到了0.46 Lm-2 h-1。此外,研究结果还表明,通过构建染料敏化的氧化锌“纳米草坪”可以有效地解决纳米材料固定化所带来的光催化活性下降的问题。与曙红Y敏化的ZnO纳米粒子膜相比,曙红Y敏化的氧化锌“纳米草坪”的光催化制氢活性是其2.26倍。(3)使用曙红Y和玫瑰红作为共敏化剂,构建了可见光催化活性更高的染料敏化氧化锌“纳米草坪”。详细探究了两种染料的混合比例、染料浓度等因素对其光催化制氢活性的影响,获得了制氢性能最佳的光催化体系。实验结果表明,曙红Y和玫瑰红之间存在着较强的协同作用。在相同的实验条件下,共敏化体系相对于单敏化体系表现出了明显的优势。共敏化的氧化锌“纳米草坪”的产氢速率最高可达0.52 L m-2 h-1,分别是同样反应条件下曙红Y单敏化体系制氢速率和玫瑰红单敏化体系制氢速率的230%和158%。此外,还利用光谱学及电化学手段对其协同作用机制进行了初步探讨。结果表明,该协同作用主要源自曙红Y和玫瑰红之间的能量转移效应。
[Abstract]:As we all know, hydrogen is regarded as the most ideal energy carrier in the future. Therefore, photocatalytic hydrogen production from water has become an important subject in the field of solar energy storage and conversion. Among many photocatalysts, zinc oxide is considered to be a promising photocatalyst because of its similar band structure and photovoltaic properties as titanium dioxide, high electron mobility, easy crystallization and anisotropic growth. It is expected to be widely used in the field of solar conversion and photocatalytic hydrogen production. In particular, ZnO nanostructures with high aspect ratio have attracted more attention because of their better electron transport performance and larger specific surface area than granular ZnO nanostructures. However, zinc oxide is a wide band gap semiconductor, only absorbed in the ultraviolet region, which limits its practical application. Recent studies have shown that dye sensitization is considered to be one of the most effective methods to broaden the working wavelength of photocatalyst. Therefore, the dye sensitized ZnO nanostructure with high aspect ratio may be an efficient visible light catalyst. It may be used to solve the problems caused by the immobilization of nanomaterials, such as the decrease of specific surface area and the decrease of photocatalytic activity. Based on the above ideas, a series of dye sensitized ZnO nanorod arrays ("nano-lawn") were constructed, and the photocatalytic activity of the catalytic system for hydrogen production was systematically explored. The main contents are as follows: (1) the preparation technology of zinc oxide "nanometer lawn" at low temperature was studied systematically. The effects of hydrothermal temperature, hydrothermal time and precursor concentration on the morphology and crystal structure of ZnO "nano-lawn" were discussed. Finally, zinc oxide "nanometer lawn" with high aspect ratio, uniform structure and stable structure was prepared. (2) using eosin Y as sensitizer, the "nanometer lawn" of zinc oxide sensitized by eosin Y was constructed. On this basis, the photocatalytic hydrogen production activity of eosin Y sensitized zinc oxide "nano-lawn" was investigated by using triethanolamine (TEOA) as a sacrificial agent under visible light irradiation. At the same time, the characteristics of dyes and the mechanism of hydrogen production were studied by spectroscopic and photochemical methods. The experimental results show that the complex system has high visible light catalytic activity and is an efficient visible light catalyst for hydrogen production. The maximum hydrogen production rate is 0.46 Lm-2 h-1. In addition, the results show that the problem of photocatalytic degradation caused by immobilization of nano-materials can be effectively solved by constructing "nano-lawn" of dye sensitized zinc oxide. Compared with eosin Y sensitized ZnO nanoparticles film, the photocatalytic activity of eosin Y sensitized zinc oxide "nano-lawn" was 2.26 times higher than that of eosin Y sensitized ZnO nanoparticles. (3) eosin Y and rose red were used as co-sensitizers. A dye sensitized zinc oxide "nanometer lawn" with higher visible light catalytic activity was constructed. The effects of the mixing ratio of two dyes and the concentration of dyes on the photocatalytic activity of hydrogen production were investigated in detail. The best photocatalytic system for hydrogen production was obtained. The experimental results show that there is a strong synergy between eosin Y and rose red. Under the same experimental conditions, the co-sensitized system has obvious advantages over the single-sensitized system. The highest hydrogen production rate of co-sensitized zinc oxide "nano-lawn" was 0.52 L m-2 h-1, which was 230% and 158% of that of eosin Y single sensitized system and rose red monosensitized system, respectively. In addition, the mechanism of synergistic action was preliminarily discussed by spectroscopic and electrochemical methods. The results showed that the synergistic effect was mainly due to the energy transfer effect between eosin Y and rose red.
【学位授予单位】：上海应用技术学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TQ116.2

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