Potential-Dependent Coadsorption of Pyridine Molecule and α-Pyridyl Radical at the Pt Electrode/Electrolyte Interface

Recently, attention on pyridine adsorption and reaction at the electrode/electrolyte interface has been revitalized in the context of pyridine-mediated reactions such as CO2 reduction. Taking Pt as an example, although numerous efforts have been made, disagreements are still unresolved regarding the potential-dependent adsorption of pyridine on the Pt electrode, which further prevents an explicit understanding of the pyridine-mediated electrochemical process at a molecular level. Here, we employed an operando electrochemical surface-enhanced Raman spectroscopy method, in combination with the density functional theory calculation and isotopic labeling of the molecule, to thoroughly study how pyridine interacts with the Pt electrode/electrolyte interface. For the first time, it is corroborated that pyridine is adsorbed on the Pt electrode in both pyridine molecule (Py) and α-pyridyl radical (α-Pyl) states. On the basis of a systematic investigation of the potential-dependent vibrational spectra, we further ...