Exploring the Unique Electrochemical Reactivity of Metallic Nanoparticles Less Than 4 nm in Diameter

来自路易斯维尔大学的弗朗西斯P. Zamborini得到了大分子，超分子和纳米化学计划的支持，以探索金属纳米颗粒独特的电化学反应性，重点关注直径小于4 nm的氧化和电置换反应。 该团队已经表明，随着直径从250 nm减小到4 nm，Au纳米颗粒的氧化电位出现负移。 位移在4 nm以下显著增加。 工作的一个目标是表征氧化电位的特定偏移的Au纳米颗粒的直径范围从250 nm到1 nm。 质谱和电化学方法的组合被用来关联的确切的纳米粒子/簇的大小与氧化电位。 这提供了重要的基本信息的稳定性的金属纳米粒子对氧化作为一个功能的大小和一个新的电化学方法来表征金属纳米粒子的大小。 他们已经发现，小金属纳米颗粒的氧化还取决于电极材料、附着到电极的方法、它们的聚集状态以及用于帮助它们氧化的配体。 他们正在系统地探索这些参数，以充分了解影响金属纳米颗粒氧化的所有因素。 电偶置换是一种电化学反应，涉及用另一种金属替换一种金属，其已用于形成有趣的合金，但尚未充分研究尺寸的函数。 这种反应也正在探索不同尺寸的纳米颗粒，重点是那些低于4纳米。 由于氧化行为在4 nm以下显著变化，因此预期电流位移反应将在该尺寸范围内显示出独特的反应性，从而允许纳米颗粒转变和合金形成，而这在较大尺寸下是不可能的。 对微小金属纳米粒子的氧化和电位移的探索将导致新化学的发现，独特的金属纳米材料的合成，以及金属纳米粒子表征的新方法的发展。该项目在许多方面具有广泛的意义和重要性。 就对科学界的影响而言，这项研究与发现涉及小金属纳米颗粒的新化学、表征金属纳米颗粒尺寸的新方法以及合成独特金属合金纳米材料的新方法有关。 它还提供了有关金属纳米颗粒稳定性的重要基础信息，这对于医学，化学分析和能源中的许多潜在应用至关重要。 它还提供了所有级别的学生，包括高中，本科，研究生和研究生的重要，多学科的培训。 这项研究的结果正在纳入本科化学课程，以教育学生有关材料的重要尺寸依赖特性，这是纳米技术研究的核心。 这些资料正在提供给其他教育机构，以便更广泛地传播。 正在主办一个为期一天的专题讨论会，专门讨论科学界的妇女，重点是生物技术和纳米技术研究。 这包括从中学生到科学专业人员的参与，包括海报和口头介绍以及一位著名女科学家的主旨演讲。 该方案正在宣传，以扩大影响。

Francis P. Zamborini from the University of Louisville is supported by the Macromolecular, Supramolecular and Nanochemistry program to explore the unique electrochemical reactivity of metal nanoparticles, focusing on oxidation and galvanic displacement reactions for those with diameters below 4 nm. The team has shown that there is a negative shift in oxidation potential for Au nanoparticles with decreasing size from diameters of 250 nm to 4 nm. The shift increases significantly below 4 nm. A goal of the work is to characterize the specific shift in oxidation potential for Au nanoparticles ranging from 250 nm down to 1 nm in diameter. A combination of mass spectrometry and electrochemical methods is being used to correlate the exact nanoparticle/cluster size with the oxidation potential. This provides important fundamental information about the stability of metal nanoparticles against oxidation as a function of size and a new electrochemical method for characterizing the size of metal nanoparticles. They have discovered that the oxidation of small metal nanoparticles also depends on the electrode material, the method of attachment to the electrode, their aggregation state, and the ligands used to assist in their oxidation. They are exploring these parameters systematically in order to gain a full understanding of all of the factors affecting metal nanoparticle oxidation. Galvanic displacement is an electrochemical reaction involving the replacement of one metal with another metal, which has been used to form interesting alloys, but has not been fully studied as a function of size. This reaction is also being explored with nanoparticles of varied size and focusing on those below 4 nm. Since the oxidation behavior changes dramatically below 4 nm, it is expected that the galvanic displacement reaction will show unique reactivity in this size regime, allowing for nanoparticle transformations and alloy formation not possible with larger sizes. The exploration of the oxidation and galvanic displacement of very small metal nanoparticles will lead to the discovery of new chemistry, synthesis of unique metal nanomaterials, and development of a new method of metal nanoparticle characterization.This project has broad significance and importance in many ways. In terms of the impact on the scientific community, this research is relevant to the discovery of new chemistry involving small metal nanoparticles, a new method for characterizing the size of metal nanoparticles, and new methods of synthesizing unique metal alloy nanomaterials. It also provides important fundamental information about metal nanoparticle stability, which is crucial for the numerous potential applications in medicine, chemical analysis, and energy. It further provides significant, multidisciplinary training of students of all levels, including high school, undergraduate, graduate, and post-graduate students. The results of this research are being incorporated into the undergraduate chemistry curriculum to educate students about the important size-dependent properties of materials, which is at the heart of nanotechnology research. This information is being made available to other educational institutions for broader dissemination. A one-day symposium is being hosted dedicated to women in science, with an emphasis on biotechnology and nanotechnology research. This includes participation from middle school students up to science professionals, including poster and oral presentations and a keynote lecture from a prominent female scientist. The program is being publicized to broaden the impact.