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Hot Electron - Understanding Electronic Excitation during Energy Dissipation and Conversion

It appears that when photons strike a metal surface (i.e., in the femtosecond regime), hot electrons are generated and diffuse into the metal before they can equilibrate with lattice vibrations. If the metal thickness is on the order of the electron mean free path, hot electrons can be collected during ballistic transport across the metal. We have demonstrated electronic excitation created during atomic or molecular processes at the surface, as shown in Figure 5. This diode scheme has been utilized to show the analogous photocurrent process and its potential application in future solar energy conversion technologies.

Our group found that surface plasmons enhance the hot electron flow generated upon absorption of photons. [Young Keun Lee, Chan Ho Jung, Jonghyurk Park, Hyungtak Seo, Gabor A. Somorjai* and Jeong Young Park*. Surface Plasmon-Driven Hot Electron Flow Probed with Metal-Semiconductor Nanodiodes. Nano Letters. 11, 4251 (2011).] We have looked into ways to improve conversion efficiency by tailoring the structures and materials of Schottky diodes. We found that hot electron flows generated on metal nanoparticles depend on the size of the Pt nanoparticles. [Hyosun Lee, Ievgen I. Nedrygailov, Changhwan Lee, Gabor A. Somorjai* and Jeong Young Park*. Chemical Reaction-induced Hot Electron Flows on Pt Colloid Nanoparticles under Hydrogen Oxidation: Impact of Nanoparticle Size. Angewandte Chemie. 54, 2340 (2015).]

Figure. Measurement of hot electron flows on Pt nanoparticles on catalytic nanodiodes.