Electrochemical SERS Measurement Revealed Interfacial Molecular States During Dynamic Changes in the 2D Diffusion and Chemical Reaction

In my study, I demonstrate that the 2D diffusion of 4,4'-bipyridine molecules on metal surfaces is strongly influenced by the electrochemical potential of the electrode and surface charge, leading to significant changes in molecular orientation.[2] In addition, optically induced potentials cause molecular condensation even in the absence of electrochemical reactions.[3] Furthermore, by focusing on the simple electrochemical reaction of H2O reduction, I observed the chemical states of water during electron transfer to interfacial water molecules from the electrode, as well as changes in hydration states at the interface. The combination of isotope effects with in-situ SERS measurements allowed us to elucidate the elementary steps of the reduction process, suggesting that hydrogen bond decoupling plays a significant role in influencing the reaction pathway. Overall, the in-situ SERS measurements provided a comprehensive understanding of molecular adsorption states and enabled precise control over chemical reactions at the interface.

[1] Kei Murakoshi et al, Present and Future of Surface-Enhanced Raman Scattering, ACS Nano 2020, 14, 1, 28–117.[2] Nobuaki Oyamada et al., In Situ Observation of Unique Bianalyte Molecular Behaviors at the Gap of a Single Metal Nanodimer Structure via Electrochemical Surface-Enhanced Raman Scattering Measurements, J. Phys. Chem. C 2019, 123, 40, 24740–24745.[3] Nobuaki Oyamada et al., Room-Temperature Molecular Manipulation via Plasmonic Trapping at Electrified Interfaces, J. Am. Chem. Soc. 2022, 144, 6, 2755–2764.