铂、钯纳米晶的可控制备及性能

发布时间：2018-03-28 05:39

本文选题：铂纳米棒　切入点：钯纳米片　出处：《浙江大学》2015年硕士论文

【摘要】：贵金属铂、钯纳米晶由于其优异的性能,被广泛应用于石油化工、能源技术、医疗和传感等诸多领域。纳米晶的性能受到其尺寸、形貌、组分、结构等各项参数的影响,调控并设计纳米晶的形貌,实现纳米晶的可控合成成为近十年来学术界研究的热点。基于以上背景,我们采用液相法合成了一系列具有特殊形貌的贵金属纳米结构,包括铂纳米棒,超薄钯纳米片和钯纳米环,并详细研究了各个纳米晶的生长机理,最后通过电化学,紫外可见光谱等手段表征了其催化和局域表面等离子体共振(LSPR)性能。本文的主要创新结果如下：(1)采用水热法,以油胺和甲醛为修饰剂成功合成了{100}晶面外露的高质量的单晶铂纳米棒,通过甲醛的用量可以调控其长径比和尺寸。高分辨透射电镜表征发现纳米棒的形成基于小颗粒定向连接机理。将铂纳米棒应用于甲醇氧化反应,与商业化Pt/C相比,展现了更好的活性和抗CO中毒能力。(2)采用液相法成功合成了厚度仅为1.1 nm的六边形超薄钯纳米片。W(CO)6, CA和CTAB对纳米片的形成至关重要。通过控制CA的用量和种子生长法,可以控制钯纳米片的尺寸。钯纳米片展示出了独特的LSPR性能,随着纳米片边长从6.4 nm增加到59.2 nm,相应的LSPR吸收峰位逐渐从820 nm红移到1067 nm。(3)以钯纳米片为种子,首次合成出六边形中空纳米环状结构。实验验证,钯纳米环是在钯原子的选择性外延生长和Br-/O2的氧化刻蚀的共同作用下形成的。这一方法还适用于异质外延,我们成功制备出了钯-铂核壳双金属纳米环。将钯纳米环应用于硝基苯酚加氢反应,展现了优越的活性和稳定性。边长为6.4nm的钯纳米环的k1值达到了60.2 s-1g-1L,分别为钯纳米片和商业化钯黑的2.2和33.4倍,且钯纳米环在10次反应后仍保存了89.3%的活性。
[Abstract]:Platinum and palladium nanocrystals of precious metals are widely used in petrochemical, energy technology, medical treatment and sensing fields because of their excellent properties. The properties of nanocrystals are affected by their size, morphology, composition, structure and other parameters. Controlling and designing the morphology of nanocrystalline and realizing controllable synthesis of nanocrystalline has become a hot topic in academic circles in recent ten years. Based on the above background, we synthesized a series of noble metal nanostructures with special morphology by liquid phase method. Including platinum nanorods, ultrathin palladium nanoparticles and palladium nanometers, the growth mechanism of each nanocrystalline was studied in detail. The catalytic and local surface plasmon resonance (LSPRs) properties were characterized by UV-Vis spectroscopy. The main innovative results of this paper are as follows: 1) hydrothermal method is used. High quality platinum nanorods with {100} crystal surface exposed were successfully synthesized with oleamine and formaldehyde as modifiers. The aspect ratio and size of nanorods can be controlled by the amount of formaldehyde. The formation of nanorods was found to be based on the directional bonding mechanism of small particles by high resolution transmission electron microscopy. Compared with commercial Pt/C, platinum nanorods were used in methanol oxidation reaction. The hexagonal ultrathin palladium nanocrystals with thickness of 1.1 nm were successfully synthesized by liquid phase method. CA and CTAB were very important to the formation of nanocrystals. By controlling the amount of CA and the method of seed growth, the hexagonal nanocrystalline palladium nanocrystals were successfully synthesized by the method of controlling the amount of CA and the growth of seeds. The size of palladium nanoparticles can be controlled. Palladium nanoparticles exhibit unique LSPR properties. With the increase of side length from 6.4 nm to 59.2 nm, the corresponding peak position of LSPR absorption gradually shifts from 820 nm to 1067 nm 路m ~ (-3). The hexagonal hollow ring structure was synthesized for the first time. The experimental results show that the nanocrystalline palladium ring is formed by the combination of selective epitaxial growth of palladium atom and oxidation etching of Br-/O2. This method is also suitable for heteroepitaxy. Palladium-platinum core-shell bimetallic nanospheres were successfully prepared and applied to the hydrogenation of nitrophenols. The K1 value of palladium nanospheres with the side length of 6.4nm is 60.2s-1g-1L, which is 2.2 and 33.4 times higher than that of palladium nanoparticles and commercial palladium black, respectively, and the palladium nanocyclic has a activity of 89.3% after 10 reactions.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

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