Bryn Merrill
Hot Electron Chemistry on Bimetallic Plasmonic Nanoparticles
Overview: The energetic electron field surrounding gold nanoparticles is exploited by the addition of a transition metal shell, such as ruthenium, to create an energized platform on which toxic molecules can react efficiently. The electron field is excited with light to push high-energy reactions towards more environmentally-friendly and breathable products.Abstract: Catalysis provides pathways for efficient and selective chemical reactions through the lowering of energy barriers for desired products. Gold nanoparticles (AuNP) show excellent promise as plasmonic catalysts. Plasmon resonances are oscillations of the nanoparticle electrons that generate energetically intense electric fields and rapidly decay into energetically excited electrons. The excited electrons have the potential to destabilize strongly bound oxygen atoms through occupation of accessible anti-bonding orbitals. Tuning the anti-bonding orbitals to make them accessible for occupancy will be achieved by coating the AuNP in a thin layer of another transition metal, such as ruthenium, silver, or platinum, creating a bimetallic nanoparticle. We will initially study the carbon monoxide (CO) oxidation reaction, where the oxygen species is strongly bound and limits reactivity, in the presence of ruthenium-gold bimetallic nanoparticles (Ru-AuNPs). The bond between oxygen and ruthenium is typically strong, which inhibits reaction rates. Excited electrons from the AuNPs can transfer to the oxygen-ruthenium anti-bonding orbital. Electrons occupy the anti-bonding orbital, weakening the bond between the atomic oxygen and the Ru-AuNPs and making the atomic oxygen much more reactive. We will be studying the physical and chemical characteristics of the synthesized Ru-AuNP catalysts with spectroscopic and microscopic techniques including: UV Vis spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM).
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