纳米金基贵金属电催化晶体材料的调控机制及自组装研究

In order to solve the increasingly serious energy crisis and environmental pollution problems, the research and application of fuel cells with non-pollution and high efficient has been attracted broad attention. Noble metals, platinum, palladium and their composites, are commonly used as the anode and cathode electro-catalyst in low temperature fuel cells. In this project, electro-catalyst of Au-based noble metals nanocrystals with controllable size, composition and shape will be planned to synthesize easily by liquid phase method. Systematic study into the regulatory mechanism will be designed，including the rate of nucleation and growth of nanocrystals and action reaction thermodynamics and kinetics. Gold as a carrier can not only reduce the consumption amount of platinum, palladium but also promote poisoning resistance of nanocrystals catalyst. Moreover, the investigation about the relationship between composition and distribution of the surface element, arrangement of the surface atoms and crystal face of high are also scheduled, which should be increase the electrochemical active and electrochemical active surface area (ECSA). Furthermore, we will explore the influence factors and rules for self-assembly of Au-based noble metals nanocrystals and preparation of the two-dimensional thin nanofilm and three-dimensional super crystal material, which will be promote the stability of electrocatalyst and achieve the synthesis of block electrochemical crystal materials. As well，the research could clarify the relation between electro-catalytic performances and the structure of crystal materials after assembling. We hope that the results will be offered to explore electro-catalyst of Au-based noble metal nanocrystals and a contribution would be made to the development of electro-catalysis nano-techniques after the project proceeding.

为了解决日益严重的能源危机和环境问题，基于无污染和高效的燃料电池的研究和应用被广泛关注。其中，贵金属铂、钯及其复合材料是目前低温燃料电池中常用的阳极和阴极的电催化剂。本项目拟采用液相法，调控纳米晶体的成核和生长速率、反应热力学和反应动力学等因素，深入了解其调控机制，实现组成、尺寸和形貌可控的纳米金（Au）基贵金属（Pt、Pd）电催化晶体材料的制备。揭示其元素组成与分布、表面原子排列、电子能级结构和晶面指数与电催化性能的关系，实现以金为载体的铂、钯纳米晶催化剂的催化活性、催化活性表面积、稳定性和抗中毒能力的显著提高。深入了解其自组装影响因素和规律，探索二维纳米薄膜和三维超晶体材料的组装，在克服纳米晶间团聚造成的催化稳定性下降的同时，可以实现其有别于独立的纳米晶催化性能的块体电催化晶体材料的制备，并阐明其组装结构与电催化性能间的构效关系。为此类催化剂的应用和纳米电催化器件的制备提供基础参考。

可控制备低贵金属用量、高功率密度和高稳定性的燃料电池催化剂是解决能源危机和环境问题的关键问题。本项目首先探讨了贵金属纳米晶的可控制备。在室温下，利用一步种子生长法制备了快速、简便的制备了高产率、单分散的17-325 nm的类球形金纳米晶。探讨了助配体氨基丁三醇在抑制二次成核和调控金纳米晶形貌方面的作用。然后为了降低铂、钯贵金属的用量和提高催化剂的催化性能，制备了铂镍金属气凝胶、三维聚苯胺凝胶负载铂纳米晶和二维钯银纳米薄膜电催化剂。利用铂-镍金属间的协同效应和气凝胶的自支撑多孔体系，增加了内部的活性位点与介质的接触，促进了电催化反应中电子传输与转移，制备的铂镍金属气凝胶在乙醇催化和氧还原反应（ORR）中具有高的电催化活性和稳定性。研究了铂镍气凝胶的形貌、组成和结构对金属气凝胶内部微结构和电催化性能的影响；阐明了铂镍纳米晶单体到水凝胶的自组装历程；并揭示了金属气凝胶的微观原子结构和宏观多孔构架与电催化性能的构效关系。利用三维网状聚苯胺凝胶的导电性能和多孔性，负载了超高密度的2-3 nm的铂纳米晶，防止小尺寸铂纳米晶的团聚，实现了其在甲醇催化方面的性能的提升。此外，将中空Pd/Ag纳米晶在界面组装成单层二维薄膜材料，并对其催化乙醇氧化的性能进行了研究。探讨了配体长度和密度等因素对纳米晶组装特性的影响；研究了加热温度和时间对纳米晶组装二维薄膜材料的影响。上述研究，为不同类型的催化剂在电催化和能源等领域的应用提供了数据依据。