Ⅱ-Ⅵ半导体核壳纳米晶、掺杂纳米晶的调控合成及性能研究：阳离子交换反应的新应用

发布时间：2018-06-05 11:13

本文选题：核壳纳米晶 + 表面等离子体共振效应　；参考：《北京理工大学》2015年硕士论文

【摘要】：本论文以半导体纳米晶及其与贵金属形成的核壳纳米结构为主要研究对象，采用非外延生长法和不同膦配体诱发的阳离子交换法相结合制备了Au@CdX（X为硫属族元素）的核壳结构纳米晶，异价掺杂的CdS纳米晶，并对其光分解水制氢、发光性能进行了研究。主要取得的成果及创新点如下： 1.我们利用非外延生长法与阳离子交换法相结合在水相中制备出具有不同厚度单晶壳层的Au@CdS核壳结构纳米晶，，且半导体CdS在三维方向上在高曲率金属Au核纳米晶表面形成直接接触和清晰的界面。基于贵金属局域表面等离子体共振（LSPR）效应，在入射光子的激发下，产生了LSPR增强下的高效电子/空穴分离及电子注入效应。对不同壳层厚度Au@CdS核壳结构纳米晶进行光分解水制氢性能的测试，当Au核尺寸增长到约为35nm时，Au35nm@CdS5nm核壳结构纳米晶的平均产氢速率高达24mmol·h-1·g-1，比同质量的CdS量子点在相同时间内产生的氢气量高1000倍以上。此外，在LSPR效应作用下，随着CdS壳层厚度的增加，核壳结构表面的LSPR逐渐减弱。辅助于FDTD理论模拟，发现了plasmon增强为主导贡献的高效光催化产氢原理。 2.利用不同膦配体提供给过渡金属离子σ电子的能力不同和不同膦配体空间位阻存在差异，进而更加灵活地调节阳离子交换反应的热力学和动力学。创新性发现不同种膦配体引发下的阳离子交换反应可用于合成更精确的半导体纳米结构，尤其是新型金属/半导体核壳纳米晶和掺杂纳米晶结晶性、成分、形貌和相关的光学性质更灵活的调控。创新性发现相比三丁基膦，三苯基膦（PPh3）作为一种能在空气中稳定存在、无刺激性气味的绿色试剂，可引发阳离子交换反应，合成Au@CdS和Pt@CdS纳米结构等形成较好的结晶性和清晰的界面，Au@CdS1-xSex复合异质结构中的组分，以及异价掺杂引起的高效的掺杂发光调控。
[Abstract]:In this thesis, semiconductor nanocrystals and their core-shell nanostructures formed with precious metals are the main research objects. Core-shell structure nanocrystals (Au@CdX(X) and heterovalent doped CdS nanocrystals were prepared by non-epitaxial growth and cationic exchange induced by different phosphine ligands. The photoluminescence properties of CdS nanocrystals were studied. The main achievements and innovations are as follows: 1. Nanocrystalline Au@CdS core-shell structures with different thickness single crystal shells have been prepared by using non-epitaxial growth method and cationic exchange method in water phase. The semiconductor CdS forms direct contact and clear interface on the surface of high curvature au nucleus nanocrystalline in three dimensional direction. Based on the local surface plasmon resonance (LSP) effect of precious metals, the LSPR enhanced high efficiency electron / hole separation and electron injection effect are generated under the excitation of incident photons. The properties of Au@CdS core-shell structure nanocrystals with different shell thickness were measured by photodissociation of water to produce hydrogen. The average hydrogen production rate of au / au nanocrystalline is as high as 24mmol h-1 g ~ (-1) when au nuclear size increases to about 35nm, which is more than 1000 times higher than that of CdS quantum dots of the same mass at the same time. The average hydrogen production rate of au ~ (35) nm CdS5nm nanocrystalline is 1000 times higher than that of CdS quantum dots of the same mass. In addition, under the action of LSPR effect, with the increase of CdS shell thickness, the LSPR on the surface of core-shell structure weakens gradually. With the aid of FDTD simulation, the principle of efficient photocatalytic hydrogen production with plasmon enhancement as the leading contribution is found. 2. The ability to supply transition metal ions 蟽 electrons with different phosphine ligands is different and the space steric hindrance of different phosphine ligands is different, which makes it more flexible to regulate the thermodynamics and kinetics of cationic exchange reactions. It has been found that cationic exchange reactions initiated by different phosphine ligands can be used to synthesize more precise semiconductor nanostructures, especially new metal / semiconductor core-shell nanocrystals and doped nanocrystallines. The morphology and related optical properties are more flexible to regulate. It has been found that compared with three Ding Ji phosphine, triphenylphosphine phosphine (PPh3), as a green reagent that can exist stably in air and has no irritant odor, can trigger cationic exchange reaction. The synthesis of Au@CdS and Pt@CdS nanostructures has good crystallinity and clear interface. The composition of au @ CdS1-xSex composite heterostructure and the high efficiency dopant luminescence regulation caused by heterovalent doping are also obtained.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.2;TB383.1

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