Light-enhanced electrochemical reactions at nanoelectrodes: The interplay between plasmonically generated hot carriers and reactant mass transport
Abstract
Nanoscale electrodes can be potent electrocatalysts due to their large electrochemically active surface area, and the fact that they allow for facet specific redox chemistry. For example, gold nanoparticles, in contrast to relatively inert bulk gold, can catalyze industrially relevant reactions such as methanol oxidation and carbon dioxide reduction. Furthermore, electrodes composed of plasmonic metals such as gold can be used for light driven electrochemistry through the creation of hot charge carriers. In order to exploit plasmonically created hot carriers in electrochemical redox reactions, the role of reactant mass transport to the nanoparticle electrode must be quantified in complex electrolyte environments and in the presence of strong electromagnetic fields. It is therefore necessary to obtain a mechanistic understanding of how the electrochemical activity of a plasmonic nanoelectrode depends on an interplay between applied electrochemical potential, relative rates of hot carrier generation and interfacial transfer, and reactant diffusion. The Link and Landes research groups at Rice University have developed novel electrochemical and imaging tools that will allow these phenomena to be studied. It is hypothesized that in plasmonic electrocatalysis at low reaction rates, sites with high field enhancement will be more reactive, while at higher rates the reactions will become mass transfer limited and reactivity will be directed by diffusion regimes around the nanoelectrode. The objective of this proposal is therefore to spatially quantify the electrochemical reactivity for single plasmonic nanoelectrodes while controlling hot carrier generation and spatial distribution. This objective will be accomplished by completion of the following project aims: (i) Extend optical nanostructure morphology analysis based on machine learning to geometries compatible with electrochemical redox reactions. (ii) Apply machine learning to in-situ optical morphology analysis of plasmonic nanoelectrode reshaping and correlate single particle reaction rates with shape changes as a function of photoexcitation energy and intensity. (iii) Spatially map electrochemical activity using a novel integrated optical and scanning electrochemical microscope to correlate shape changes directly with reactive sites in and outside the mass transfer limit for reactants. Key outcomes of this project include: ¥ A generalized machine learning algorithm for real time size determination of plasmonic nanostructures in electrochemically relevant environments. ¥ An understanding of the role of mass transport in the design of high efficiency catalysts. ¥ The ability to tailor the shape of a nanostructure to optimize its catalytic properties. Successful completion of the project aims will result in fundamental knowledge that will enable the development of compact and efficient energy generation and storage solutions that would directly benefit both society and the Army. Page C
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 12, 2022
- Source ID
- W911NF2210295
Entities
People
- Stephan Link
Organizations
- Army Contracting Command
- Rice University
- United States Army