氧化物纳米涂层的热稳定性及其与贵金属界面特性研究

This project proposes to investigate the deposition of some metal oxides (e.g., TiO2, ZnO, HfO2, Al2O3, etc.) nano coatings on nanostructures of noble metals (Ag, Au, etc.), which cover fully the nanostructures of noble metals, to improve the thermal stability in morphology of the metallic nanostructures, to improve their adsorption ability of specific molecules, and to create the ability to remove those molecules and other adsorptions by photocatalytic reduction. .The ideas of this study are: (1) by a thorough study on the coating materials and coating processing to find a way to coat the nanostructures of noble metals with ultra thin metal oxides layers completely, to improve the thermal stability of the metallic nanostructures in morphology, as the thermal stability of the metal oxides in morphology is much better at nanometer scale; (2) by coating completely the metallic nanostructures with metal oxides layers to improve the adsorption ability of specific molecules such as PCBs, or proteins, to enhance the Raman signal intensity of these molecules; (3) by using the photocatalytic activity of the metal oxides nano coatings to remove the adsorptions on the surface of the nano systems, to keep the surface of the metallic nanostructures clean for reuse. Another point of this study is the interface between the metallic nanostructures and the nano coatings of metal oxides, which may influence greatly the surface-enhanced Raman scattering ability of the system. .By carefully selecting the coating materials, a thorough study on the thermal stability of these coatings, and the interfacial reaction behavior of the coatings with the metallic nanostructures, it could be possible to produce surface-enhanced Raman scattering substrates with high sensitivity and high stability, which can be reused. This study could also deliver new knowledges and understandings on the thermal stability of metal oxides at nanometer scale, and on the interface properties between metal oxides and metals at such a tiny scale.

本项目拟开展特定氧化物纳米涂层的制备、热稳定性、以及涂层与贵金属纳米结构间的界面特性研究。目的在于利用氧化物纳米涂层较好的热稳定性（形貌、性能、结构等），实现对贵金属纳米结构的表面和形貌保护，提高贵金属纳米结构表面增强拉曼散射性能的时间稳定性；利用氧化物涂层特有的一些性质，如：对特定分子的高吸附特性、催化降解特性等，提高贵金属纳米结构对特定分子的吸附能力，增强其表面增强拉曼散射性能，以及利用涂层的催化降解作用去除吸附的检测分子和污染物，实现对贵金属纳米结构的可重复利用。本项目需要开展对氧化物涂层体系、制备技术和性能热稳定性的系统研究，并需要深入研究纳米尺度下氧化物涂层与贵金属纳米结构之间的界面特性，并发展相应的界面控制技术，实现对其界面状态的调控。本项目研究有助于理解纳米材料热稳定性的尺度效应以及氧化物/贵金属的界面效应，并有助于发展出可实用化的表面增强拉曼散射基片。

本项目主要针对贵金属纳米结构稳定性差，难以作为表面增强拉曼散射基片实际使用的问题，提出开展特定氧化物纳米涂层的制备、热稳定性、以及涂层与贵金属纳米结构间的界面特性研究，利用氧化物纳米涂层较好的热稳定性实现对贵金属纳米结构的表面和形貌保护，提高贵金属纳米结构表面增强拉曼散射性能的稳定性，同时为发展高性能表面增强拉曼散射基片的设计方法，并发展基于表面增强拉曼散射的痕量分析技术方法。本项目研究利用原子层沉积技术制备出了纳米厚度的氧化铝、氧化钛、氧化铪涂层，并实现了对银纳米棒的完整包覆，大大提高了复合结构的热稳定性、化学稳定性、存放稳定性等。通过原子层沉积工艺的调整，实现了对氧化物纳米涂层中针孔率的控制，研究获得了针孔率同复合纳米结构热稳定性之间的关联性，并利用具有针孔的氧化物纳米涂层包覆银纳米棒的复合结构实现了对不同性质分子表面增强拉曼测量。研究了Au纳米棒长程有序排布对于其多极子共振模式的影响规律，并利用该耦合作用进一步提高了拉曼检测敏感度。提出了基于主成分分析的“杠杆法则”和“三角形法则”，并利用对分子吸附动力学差异的校正，实现了对二元和三元体系中痕量待测分子的成分分析，并将此方法成功拓展到多元体系。这些工作，为高性能实用型表面增强拉曼散射几篇的设计和制备，以及基于表面增强拉曼散射的定性和定量分析打下了基础。