Kexun Chen

Date of Award

Fall 2023

Document Type

Open Access Dissertation


Chemistry and Biochemistry

First Advisor

Hui Wang


We employ surface-enhanced Raman scattering (SERS) as an in situ spectroscopic tool, in conjunction with density functional theory (DFT) calculations, to develop a detailed mechanistic understanding of plasmon-driven photocatalytic reactions and heterogeneous transfer hydrogenolysis reactions of molecular adsorbates on metallic nanostructure surfaces. The excitation and decay of plasmon resonances in metallic nanostructures give rise to intriguing photophysical and photochemical effects, including the generation of hot charge carriers, local field enhancements, and photothermal transduction. These effects can be intentionally harnessed to drive or enhance interfacial molecular transformations along unconventional reaction pathways. The first part of the thesis focuses on the plasmon-driven photocatalytic dimerization of aniline and nitrobenzene derivatives, elucidating the relationship between the chemical nature of adsorbate-metal interactions and reaction reactivities. Additionally, we utilize the dimerization reaction of para-nitrothiolphenyl as a model system to assess the relative contributions of photothermal and nonthermal effects. As a highly sensitive vibrational spectroscopic technique, SERS provides fingerprints of molecular structures, offering valuable chemical and structural information. With sufficient temporal resolution, SERS serves as an ideal tool to identify reaction intermediates and resolve the reaction kinetics of heterogeneous catalytic reactions. Similarly, to the first part, we investigate the impact of adsorbate-metal interactions on chemical reactions. However, instead of plasmon-driven photocatalytic reactions, we focus on studying the metal-surface catalyzed transfer hydrogenolysis of nitrobenzene derivatives. We further demonstrate the feasibility of plasmonically enhancing the reaction, leading to an increased reaction rate and shortened induction time.


© 2024, Kexun Chen

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