Electrochemical and Plasmonic Photochemical Oxidation Processes of para-Aminothiophenol on a Nanostructured Gold Electrode

The analysis of plasmonic photoelectrochemical reactions on nano-structured noble metal electrodes is an attractive field, but little is known about the detailed competition between the photochemical and electrochemical reaction processes, product selectivity, and synergistic kinetics. In this work, para-amino-thiophenol (PATP), as a probe molecule in surface-enhanced Raman spectroscopy (SERS), was used to investigate electrochemical and photochemical oxidation on nanostructured gold electrodes. Using electrochemical SERS (EC-SERS) and density functional theory (DFT) calculations, the sophisticated oxidation process and the selectivity of PATP oxidation (electrochemical oxidation and photochemical oxidation) under different conditions were determined. Moreover, based on the provided oxidation pathways of PATP on the gold electrode, the oxidation kinetics of PATP was studied by COMSOL simulation and a spectroscopic tool. The increasing rate constant of cationic radical formation due to hot holes at a high laser power has induced the selective generation of photochemical products. This work built a system to modulate the reaction selectivity and will inspire photoelectrochemical kinetic research in other plasmonic metal electrode-adsorbate systems of nanostructures.