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

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.