多级纳米阵列结构光电阳极材料的制备及性能研究

发布时间：2018-05-08 22:25

本文选题：光电阳极 + 光电化学分解水　；参考：《北京化工大学》2015年硕士论文

【摘要】：近几十年,能源危机成为全球关注的问题,开发利用新能源已经成为国内外研究的热点,光电化学(PEC)分解水制氢为人类获取新能源提供了一种有效的方法。传统的光电阳极材料主要是以Ti02,ZnO, WO3等为代表的半导体氧化物材料,但这些传统光电阳极材料存在着可见光利用率低、光生电子-空穴易复合和量子效率低等问题,限制了它们的近一步应用。本文在传统的光电阳极材料ZnO, WO3基础上,通过构筑ZnO纳米阵列多级结构、沉积贵金属金纳米颗粒和引入水滑石(LDH)助催化剂等方法,在提高活性位,抑制电子-空穴复合,扩大光谱吸收以及提高水氧化动力学等方面实现了对光电阳极材料的优化,提高了光电化学分解水的性能。同时,通过DFT理论计算的方法对光电阳极材料在光电化学分解水的过程中一些机理进行了探索。具体研究内容如下：1、通过水热法合成了ZnO NR@NP核壳阵列,研究表明ZnONR@NP核壳阵列多级结构有利于ZnO活性位点的暴露,提高了光电化学分解水的效率。进一步用Au纳米颗粒进行修饰后,Au-ZnO NR@NP阵列光电流有很大提高,在电压0.6 V vs. Hg/Hg2Cl2下光电流密度为1.47 mA·cm-2,而ZnO NR@NP阵列为1.17 mA·cm-2。 Au-ZnONR@NP光电化学分解水性能的增强是由于金纳米颗粒形成电子陷阱抑制了ZnO光生电子-空穴对的复合,同时,金纳米颗粒的SPR效应提高了可见光的利用率。密度泛函理论(DFT)计算进一步证明ZnO的光激发电子容易转移到Au纳米颗粒上。该工作提供了一个有效的制备贵金属／半导体多级结构纳米阵列的方法。2.通过电合成的方法实现了NiFe-LDH纳米片在W03纳米线阵列上的有序生长,并探究了在光电化学分解水方面NiFe-LDH与W03之间的协同作用。W03本身具有光催化性能,NiFe-LDH具有优良的电催化性能,两者结合形成的WO3@NiFe-LDH核壳纳米阵列显著增强了光电化学分解水的性能。NiFe-LDH壳作为助催化剂增加了整个体系的反应动力学,同时抑制了W03电子-空穴对的复合。本论文提出了一个制备半导体氧化物和LDH复合多级纳米阵列材料的方法,其显著提高了半导体金属氧化物的PEC分解水性能。
[Abstract]:In recent decades, the energy crisis has become a global concern, the development and utilization of new energy has become a hot spot at home and abroad. Photoelectrochemical PECs provide an effective method for human to obtain new energy. The traditional photoanode materials are mainly semiconductor oxide materials, such as Ti02ZnO, WO3, etc. However, these traditional photoanode materials have some problems, such as low utilization of visible light, easy recombination of photogenerated electron-hole and low quantum efficiency, etc. Limit their further application. In this paper, based on the traditional photoanode materials, ZnO, WO3, the multistage structure of ZnO nanoarrays, the deposition of noble metal gold nanoparticles and the introduction of hydrotalcite WO3 co-catalysts are used to improve the active sites and inhibit the electron-hole recombination. The properties of photoelectrochemical decomposition of water have been improved by optimizing the photoanode materials in the aspects of expanding the absorption spectrum and improving the kinetics of water oxidation. At the same time, the mechanism of photoelectrochemical decomposition of water was investigated by DFT theory. ZnO NR@NP core-shell arrays were synthesized by hydrothermal method. The results show that the multilevel structure of ZnONR@NP core-shell arrays is beneficial to the exposure of ZnO active sites and improves the efficiency of photochemical decomposition of water. After further modification with au nanoparticles, the photocurrent of Au-ZnO NR@NP arrays was greatly improved, with a photocurrent density of 1.47 Ma cm-2 at a voltage of 0.6 V vs. Hg/Hg2Cl2 and a 1.17 Ma cm-2 of ZnO NR@NP arrays. The enhancement of the photochemical decomposition of water by Au-ZnONR@NP is due to the formation of electron traps in gold nanoparticles which inhibit the photogenerated electron-hole pairs of ZnO. At the same time, the SPR effect of gold nanoparticles increases the utilization rate of visible light. The density functional theory (DFT) calculation further proves that the photoexcited electrons of ZnO are easily transferred to au nanoparticles. This work provides an effective method for preparing noble metal / semiconductor multilevel nanoarrays. The ordered growth of NiFe-LDH nanowires on W03 nanowire arrays was realized by electrosynthesis. The synergism between NiFe-LDH and W03 in photochemical decomposition of water was investigated. The WO3@NiFe-LDH core-shell nanoarrays formed by the combination can significantly enhance the photochemical decomposition of water. NiFe-LDH shell as a co-catalyst increases the reaction kinetics of the whole system and inhibits the recombination of the W03 electron-hole pair. In this paper, a method of preparing semiconductor oxide and LDH composite multistage nanoarrays is proposed, which improves the PEC decomposition water performance of semiconductor metal oxides.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O646.54;TQ116.2

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