Transmission Electron Microscope to Study Plasma-Driven Solution Electrochemistry
Abstract
This research infrastructure program proposal is to extend the diagnostic capabilities used in the MURI ÒPlasma-driven solution electrochemistryÓ with high resolution in liquid ex situ Transmission Electron Microscopy (TEM) and enable the development of a first-of-its-kind in situ TEM plasma electrolysis capability inspired by and advancing the state-of-the-art in situ electrolysis TEM studies. This new capability will enable, for the first time, in situ investigations of electrochemical reactions near the plasma-liquid interface leading to the formation of nanomaterials. Plasma-driven solution electrochemistry (PDSE) is a new field with many unsolved important fundamental questions. Plasma-induced solution chemistry can be driven by electrons, ions, photons, and radicals. In thermal catalytic, electrocatalytic, and plasmon-driven chemical transformations, metal surfaces play key roles. In contrast, in plasma-driven processes, electrons are produced in a gas phase plasma and injected into the interfacing liquid without the need for a solid electrode. The high-power density in plasmas enables exceptionally large yields of electrons, some having energies as high as 10 eV or more, leading to a high concentration of electrons in a near plasma-liquid interfacial region with a thickness up to a few tens of nm. These conditions enable unique chemical transformations. Controlling these hot electron-driven chemical transformations in the liquid requires an in-depth understanding of the underpinning processes, an understanding that is currently lacking and is the research focus of the MURI. The high resolution TEM requested in this research infrastructure program will enable answering key scientific questions about the nucleation and growth of nanoparticles formed in plasma-driven solution electrochemistry. Answering these key science questions is not possible through traditional ex situ TEM, in which the evaporation of the solution in the vacuum of the TEM causes particles to agglomerate, making it impossible to observe particles in their native state. Hence, ex situ in liquid TEM analysis, enabled by the requested TEM, will be advantageous over vacuum ex situ TEM, and offer the possibility of extending TEM studies beyond nanoparticle growth to plasma electrolysis for polymerization. Moreover, in situ liquid TEM will enable first in their kind insights into the earliest stages of particle growth. A key hypothesis, supported by modeling, is that plasma induced cluster formation and particle growth proceed on microsecond to second time scales making them accessible by in situ TEM. The proposed in situ TEM would enable us to bridge a notorious gap in the in situ detection of small particles by complementing available optical diagnostics capabilities, which focus on monitoring initial precursor chemistry of nucleation and on larger particles. This will lead to transformational advances in new materials synthesis and in our ability to use plasmas for selective, efficient, green chemical transformation. The proposed TEM has the capabilities that are required to answer the MURIÕs fundamental scientific questions, including �ngstrom-level spatial resolution for imaging and chemical analysis through Energy Dispersive X-ray Spectroscopy (EDS). The newly proposed in situ plasma-solution electrolysis TEM analysis, which expands on current in situ electrolysis TEM methods, has the potential to provide a treasure trove of new fundamental insights that will provide unique experimental benchmark information for theoretical work on computational nucleation theory and plasma-liquid interaction modeling performed within the MURI.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 31, 2020
- Source ID
- W911NF2010322
Entities
People
- Peter J Bruggeman
Organizations
- Army Contracting Command
- United States Army
- University of Minnesota