低维纳米尺度金属（Cu、Ni）的腐蚀行为及电化学特征研究

An understanding of the stability and corrosion of metal particles, wires and thin films at nanometer scale in the reaction environments, compared with their bulks, is of great importance due to their increasing demands in nanoelectronic devices, heterogeneous catalysis, sensor, fuel cell, solar cell and biological medicine applications. The increased surface to volume ratio of nano-scale metals achieved by particle size reduction leads to exceptional corrosion and unusual electrochemical behaviours that differ from those of their bulk macroscopic counterparts. In this proposal, focused ion beam (FIB) micro/nano-fabrication, environmental scanning electron microscopy(ESEM) and microelectrode electrochemical measurement techniques are combined to develop experimental methods for the study of corrosion and electrochemistry of nano-scale metals. The corrosion behaviours of Cu and Ni nanoparticles and nanowires, and their nano-layer specimens in aqueous solutions are to be investigated in detail. The morphology and microstructure of corrosion products and passive films formed on the surface of nano-scale metals will then be characterized using high resolution electron microscopy. The electrochemical tests such as corrosion potential, cyclic voltammetry and potentiodynamic polarization curves of individual metal nanowire and nano-layer sample are proposed to study the electrochemical corrosion mechanism of these nanomaterials. Based on the experimental results and the thermodynamic calculations, we will be able to clarify the intrinsic relation between microstructure and surface property of such nano-scale metals and their corrosion behaviours. Moreover, the adsorption and diffusion of water and oxygen molecular and typical ions such as H+,OH-,Cl-, etc. at the interface between nanometal surface and solution , together with the kinetics of nanometal electrode process, will be well understood. Through the comprehensive research in this proposal, it is expected to better understand the corrosion behaviours of nano-scale metals in the aqueous solutions and establish fundamental theoretical models of corrosion and electrochemical processes, which will not only be beneficial to the application of such nanomaterials, but also advance the development of corrosion research in micro/nano-scale.

针对低维金属材料尺寸纳米化所表现出来的特异腐蚀现象及电化学行为，本课题通过将聚焦离子束（FIB）纳米微加工技术、环境扫描电子显微系统（ESEM）原位观察分析技术以及微电极电化学测试技术等先进实验手段综合集成，发展建立纳米尺度金属腐蚀和电化学研究实验方法；基于高分辨电子显微分析技术，系统研究常用金属Cu、Ni的纳米颗粒、纳米线以及纳米薄层试样在NaCl水溶液体系中的腐蚀行为，并通过单体纳米金属材料电化学测试分析，研究Cu、Ni低维纳米金属的腐蚀电化学过程机制；结合热力学计算和理论分析，深入研究纳米金属微观结构和表面物理化学特性与其腐蚀行为的内在关系，探讨纳米金属表面/溶液界面吸附、扩散理论，阐释纳米金属电极过程动力学机制，初步建立Cu和Ni等低维纳米金属腐蚀及电化学理论模型，为实现该类金属纳米材料的大规模实际应用和促进腐蚀学科向微观体系创新发展奠定理论和实验基础。

纳米尺度金属的小尺寸效应、超高比表面积以及表面大量缺陷、悬空化学键等活性反应位，使其具有完全不同于传统块体金属的优异化学反应活性。金属纳米材料在实际应用中绝大部分是在溶液环境下，或处于有液体接触的复杂多相体系中，腐蚀问题不可避免。目前关于纳米尺度金属材料在溶液体系环境中的腐蚀规律和机理、以及纳米尺度金属腐蚀电化学行为等方面的研究还十分匮乏，而纳米金属材料在溶液中的腐蚀失效问题是该类材料实现真正大规模实际应用必须要面对和解决的关键问题。. 本课题研究发展建立了一套包括纳米金属电极制样、组装、测试及微观分析的系统化材料腐蚀纳米尺度研究方法，首次采用离子束刻蚀微纳加工技术，成功制备了尖端尺度约为20-50nm的针状金属电极试样，该类纳米针状试样具有很好的电子穿透性，通过HR-TEM准原位观察纳米金属电极试样在电化学极化处理前后的表面微观结构变化，可以对金属在各种环境条件下所形成的表面氧化膜、钝化膜或腐蚀产物提供直接的观察分析，对研究金属氧化、腐蚀行为和机理具有重要的实际意义。. 通过微纳米电化学和高分辨电子显微分析相结合，系统研究了金属Cu、Ni、不锈钢等在NaCl水溶液和含硫水溶液环境中腐蚀行为及钝化膜微观结构，首次采用制备的纳米电极试样获得了Cu、Ni、不锈钢等结构材料钝化膜的高分辨电子像，为研究金属钝化膜结构提供了直接证据；基于纳米电化学测试技术，深入研究了单根Cu纳米线在空气和水溶液中的电化学腐蚀行为，显示了传统块体材料完全不同的腐蚀特征和机理.. 本课题通过发展微纳米材料电化学和高分辨电子显微分析研究方法，为在纳米尺度上研究金属腐蚀奠定了良好的基础，对促进腐蚀学科向微观原位发展起到积极的促进作用。本课题共发表论文19篇（14篇SCI，15篇EI），在国内外学术会议做口头报告9次，培养博士研究生两名，硕士研究生四名。