CAREER: Electro-Shock Synthesis of High Entropy Alloy Nanoparticles from Sub-Femtoliter Reactors

在美国国家科学基金会化学部大分子、超分子和纳米化学（MSN）项目的支持下，北卡罗来纳大学教堂山分校的Jeffrey E. Dick博士致力于开发一种在室温下合成高熵合金纳米颗粒的创新方法。高熵合金纳米颗粒含有5种或5种以上均匀分布在颗粒中的等摩尔金属元素。这种纳米颗粒可能表现出不同寻常的化学性质，在催化、能量储存和转换装置中具有重要意义。然而，要在室温下合成这些纳米颗粒，并精确控制它们的形状、大小、组成和在不同基质上的表面覆盖，是一项挑战。迪克博士的团队正在开发一种新的电化学方法，在室温下将高熵合金纳米颗粒沉积在导电表面上。本研究努力实现电沉积过程的机理理解，以便精确控制纳米颗粒的结构和性能。参与该项目的学生将获得合成纳米材料的经验。学生还将使用最先进的纳米科学工具来研究高熵合金纳米颗粒及其反应性。该项目将通过纳米材料教育、研究和科学参与（NANOVERSE）项目，加强代表性不足的少数民族的参与。NANOVERSE项目将吸引北卡罗来纳州传统黑人学院和大学（HBCUs）的学生。工作坊活动的目的是激发他们从事纳米科学、电化学和材料科学的研究生工作。最后，NANOVERSE计划将为中等教育STEM教师提供资源，以便在高中课堂上向学生介绍纳米科学。目前正在开发的电击合成技术涉及到在悬浮于非水相的亚飞升水滴中由金属盐前体电沉积高熵合金纳米颗粒。该项目的总体目标是了解电沉积机制和影响纳米颗粒形状、大小、形态、微观结构和表面覆盖的因素。高水平的控制需要详细了解反应性和水滴，油连续相和电极表面之间的边界。第一个目标是在单个纳米颗粒水平上理解和量化成核和生长机制，并探测离子转移热力学和动力学。第二个目标是了解表面活性剂、应用电位和退火对纳米颗粒形貌和微观结构的影响。第三个目标是探索衬底效应，以及表面如何影响纳米液滴的几何形状和由此产生的高熵合金纳米颗粒。这些结果可能在电催化、能量储存和转换、纳米材料以及利用高熵合金纳米颗粒的下一代生物传感器等领域具有广泛的意义。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program of the Division of Chemistry at the National Science Foundation, Dr. Jeffrey E. Dick of the University of North Carolina at Chapel Hill aims to develop an innovative approach to the synthesis of high entropy alloy nanoparticles at room temperature. High entropy alloy nanoparticles contain five or more equimolar metallic elements homogenously distributed through the particle. Such nanoparticles may display unusual chemical properties and have implications in catalysis, energy storage and conversion devices. However, it is challenging to synthesize these nanoparticles at room temperature with precise control of their shape, size, compostion, and surface coverage on different substrates. Dr. Dick's group is developing a novel electrochemical methodology to deposit high entropy alloy nanoparticles on conductive surfaces at room temperature. This research strives to achieve a mechanistic understanding of the electrodeposition process in order to enable precisel control of the nanoparticle structure and properties. Students working on this project will gain experience in synthesizing nanomaterials. Students will also use state-of-the-art nanoscience tools to study high entropy alloy nanoparticles and reactivity. This project will enhance the participation of underrepresented minorities through the Nanomaterials Outreach via Education, Research, and Scientific Engagement (NANOVERSE) program. The NANOVERSE program will engage students in Historically Black Colleges and Universities (HBCUs) in North Carolina. The workshop activities are designed to inspire them to pursue graduate work in nanoscience, electrochemistry, and materials science. Finally, the NANOVERSE program will give secondary education STEM teachers resources to introduce students to nanoscience in their high school classrooms. The Electro-Shock synthesis being developed involves the electrodeposition of high entropy alloy nanoparticles from metal salt precursors in sub-femtoliter water droplets that are suspended in a non-aqueous phase. The overarching goal of this project is to understand the electrodeposition mechanism and factors that influence the nanoparticle shape, size, morphology, microstructure and surface coverage. A high level of control requires a detailed understanding of the reactivity and the boundary between the water droplet, the oil continuous phase, and the electrode surface. The first goal is to understand and quantify the nucleation and growth mechanisms at the single nanoparticle level and probe ion transfer thermodynamics and kinetics. The second goal is understanding the effect of surfactant, applied potential, and annealing on nanoparticle morphology and microstructure. The third goal is probing substrate effects and how surfaces influence the nanodroplet geometry and the resulting high entropy alloy nanoparticle. These results could have broad implications on the fields of electrocatalysis, energy storage and conversion, nanomaterials, and next-generation biosensors that take advantage of high entropy alloy nanoparticles.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.