(240a) Elucidating Mechanisms of Plasmon Decay in Multimetallic Nanostructures for the Rational Design of Plasmonic Photocatalysts

Plasmonic metal nanoparticles are promising platforms for manipulating the flow of electromagnetic energy at the nanometer length scale. Upon light illumination, plasmonic nanoparticles act to confine the energy of incoming radiation in the form of amplified electromagnetic fields at their surface. The energy of these fields can then be dissipated either through radiative scattering of photons or non-radiative excitation of energetic charge carriers (i.e. absorption) in the metal nanoparticle. Recently, there has been increasing interest in controlling these plasmon decay processes with the ultimate goal of designing nanostructures with highly localized charge carrier generation at specific locations in the nanoparticle. For example, manipulating the location of the charge carrier excitation (photon absorption) in terms of surface versus bulk excitations is critical in a number of applications, including plasmonic photocatalysis.

In this contribution, we shed light on the physical framework describing the flow of energy in multimetallic plasmonic nanoparticles. We do so by systematically investigating, through experimental and modeling approaches, the LSPR decay mechanisms in Ag-Pt and Au-Pt core-shell nanoparticles of different shapes and sizes. We demonstrate that coating plasmonic nanostructures with non-plasmonic metals can in the preferential dissipation of energy through the surface layers of the nanoparticles. We show that the extent of this energy dissipation depends heavily on the electronic structure of the constituent metals. We conclude by providing insights into how this physical framework can aid the rational design of multicomponent plasmonic for plasmonic photocatalysis.