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Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters
Published on: July 8, 2013
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Hot carrier multiplication in plasmonic photocatalysis
Linan Zhou1,2, Minhan Lou2, Junwei Lucas Bao3,4
1Department of Chemistry, Rice University, Houston, TX 77005.
Summary
This study reveals that thermalized hot carriers, not nonthermal ones, primarily drive the H2-D2 exchange reaction photocatalyzed by copper nanoparticles. The findings suggest hot carrier multiplication and a vibrational excitation mechanism for enhanced photocatalysis.
Area of Science:
- Photocatalysis
- Plasmonics
- Nanomaterials
- Surface Chemistry
Background:
- Metal nanostructures generate light-induced hot carriers via surface plasmons for photocatalysis.
- The distinct roles of nonthermal and thermalized hot carriers in photocatalytic reactions remain largely unidentified.
Purpose of the Study:
- To elucidate the specific roles of hot carriers in the H2-D2 exchange reaction photocatalyzed by copper nanoparticles.
- To investigate the mechanism driving this photocatalytic process.
Main Methods:
- Experimental observation of the H2-D2 exchange reaction using Cu nanoparticles under light irradiation.
- Analysis of external quantum yield and its intensity dependence.
- Development and application of a simplified model for thermalized hot carrier quantum yield.
- Quantum mechanical studies of surface bond excitations.
Main Results:
- The H2-D2 exchange reaction is predominantly driven by thermalized hot carriers.
- An S-shaped intensity dependence of the external quantum yield was observed, exceeding 100% at high intensities, indicating hot carrier multiplication.
- A simplified model successfully reproduced the reaction's kinetic features, supporting the thermalized hot carrier mechanism.
- Quantum mechanical calculations identified vibrational excitations of the Cu-H bond as the likely activation mechanism.
Conclusions:
- Thermalized hot carriers are the primary drivers of the H2-D2 exchange reaction photocatalyzed by Cu nanoparticles.
- Hot carrier multiplication likely contributes to the high quantum yields observed.
- The photocatalytic mechanism involves vibrational excitations of the surface Cu-H bond, highlighting the role of low-energy thermalized hot carriers.
