Seeded Growth of Noble-Metal Nanocrystals

贵金属纳米晶体的种子生长

• 批准号: 1215034
• 负责人: Younan Xia
• 金额: $ 54.5万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1215034&HistoricalAwards=false
• 关键词: Seeded; Growth; Noble; Metal; Nanocrystals

TECHNICAL SUMMARY:This project, supported by the Solid State and Materials Chemistry (SSMC) program at NSF, will build a scientific basis for the synthesis of noble-metal nanocrystals with controlled properties for a variety of applications. The key approach is to separate and then independently control the nucleation and growth steps using a seed-mediated method. The research will be organized into four thrusts: i) Synthesis and characterization of single-crystal, cubooctahedral seeds made of Ag, Au, Pd, or Pt, and with sizes below 10 nm. The effects of capping agent, precursor, and oxidative etching on the crystallinity, yield, and size distribution of the seeds will all be examined. ii) Growth of metals same as the seeds. This work will seek to correlate the reduction kinetics with the growth modes, including site-selected overgrowth, conformal coating, and dendritic growth. It will also develop a screening method for rapid identification of capping agents capable of promoting the formation of specific facets. iii) Growth of metals different from the seeds. This work will address issues such as galvanic replacement that will occur spontaneously when the metal for seeds is more reactive than the metal to be grown by introducing a strong reducing agent to setback the replacement reaction. It will also fully explore the core-shell nanocrystals in terms of control over composition, shape, and shell thickness. iv) Properties and applications of the novel nanocrystals. In addition to a systematic study of the optical properties for nanocrystals with different sizes, shapes, and compositions, this work will investigate how the shells with various thicknesses shield the plasmonic excitation of the cores. It will also systematically investigate the effect of a substrate in forming hot spots with nanocrystals having different shapes. Furthermore, it will examine the catalytic and electrocatalytic properties of core-shell nanocrystals with both well-defined facets on the surface and tightly controlled thicknesses for the shellsNON-TECHNICAL SUMMARY:Interest in noble-metal nanocrystals with controlled sizes and shapes has grown steadily because of strong correlations between the size/shape of nanocrystals and chemical, physical, electronic, optical, magnetic, and catalytic properties. The interest has also been enhanced by the technological applications of these nanocrystals in areas ranging from catalysis (e.g., in fuel cells and catalytic converters) to biomedical research (e.g., as contrast and therapeutic agents). However, attempts to systematically and predictably control these properties have been met with limited success. One barrier is the lack of a mechanistic understanding and experimental control of the evolution pathway from atoms to nuclei, seeds, and finally nanocrystals. This work will bring significant advances to the field by unraveling the essential knowledge and design rules for synthesizing noble-metal nanocrystals with controlled sizes, shapes, morphologies, compositions, and structures crucial to various applications. This research will have profound impacts on the society in the following aspects: i) developing novel materials for sensing, biomedical applications, and catalysis that will address issues related to national security, health, environment, and energy; ii) forging links between different scientific fields that include solid state chemistry, condensed matter physics, surface science, materials science, colloid science, catalysis, and photonics; iii) enhancing both graduate and undergraduate education through multidisciplinary research and collaboration; iv) generating and disseminating new scientific knowledge resulting from the proposed work through peer-reviewed publications, reports, seminars, conference presentations, undergraduate and graduate teaching, summer school lectures, and websites; and v) promoting diversity in higher education by engaging women, minorities, and other underrepresented groups into the research program.

技术摘要：该项目在NSF的固态和材料化学（SSMC）计划的支持下，将建立科学基础，以综合具有各种应用程序具有控制性能的贵族金属纳米晶体。关键方法是使用种子介导的方法独立地分离并独立控制成核和生长步骤。这项研究将分为四个推力：i）由Ag，Au，Pd或Pt制成的单晶，Cuboctahedral种子的合成和表征，并且尺寸低于10 nm。封盖剂，前体和氧化蚀刻对种子的结晶度，产率和尺寸分布的影响均应研究。 ii）金属的生长与种子相同。这项工作将旨在将还原动力学与生长模式相关联，包括现场选择的过度生长，保形涂层和树突状生长。它还将开发一种筛选方法，用于快速识别能够促进特定方面形成的封盖剂。 iii）金属的生长与种子不同。这项工作将解决诸如电流替代品之类的问题，当种子的金属比金属更具反应性时，通过引入强还原剂来挫折替换反应来生长的金属更具反应性。它还将以控制成分，形状和壳厚度的控制来充分探索核壳纳米晶体。 iv）新型纳米晶体的特性和应用。除了对具有不同尺寸，形状和组成的纳米晶体的光学性质进行系统的研究外，这项工作还将研究具有各种厚度的壳的壳如何遮盖核心的等离子体激发。它还将系统地研究底物在形成具有不同形状的纳米晶体的热点方面的效果。此外，它将检查核心壳纳米晶体的催化和电催化特性，表面上都有明确定义的面和紧密控制的厚度，用于Shellsnon-technical-technical摘要：对贵族金属晶体的兴趣，具有控制尺寸和形状的高质量和塑形的质量，并且具有强度的尺寸，因为NINAN在NINAN之间稳定地均具有强度磁性和催化特性。这些纳米晶体在从催化（例如，在燃料电池和催化转化器中）到生物医学研究（例如，作为对比度和治疗剂）的技术应用也提高了兴趣。但是，实现了系统和预测的控制这些特性的尝试，成功的成功率有限。一个障碍是缺乏对从原子到核，种子再到纳米晶体的演化途径的机械理解和实验控制。这项工作将通过揭示与对各种应用至关重要的受控大小，形状，形态，形状，形状和结构的贵族金属纳米晶体的基本知识和设计规则，从而为现场带来重大进步。这项研究将在以下方面对社会产生深远的影响：i）开发新型材料，以解决与国家安全，健康，环境和能源有关的问题； ii）在不同的科学领域之间建立联系，包括固态化学，凝结物理学，表面科学，材料科学，胶体科学，催化和光子学； iii）通过多学科研究和合作来增强研究生和本科教育； iv）通过同行评审的出版物，报告，研讨会，会议演讲，本科和研究生教学，暑期学校的讲座和网站来产生和传播由拟议的工作产生的新科学知识； v）通过使妇女，少数民族和其他代表性不足的群体参与研究计划来促进高等教育的多样性。