Potential Controlled Redox Cycling of 4-Aminothiophenol by Coupling Plasmon Mediated Chemical Reaction with Electrochemical Reaction

•We studied the interplay between plasmon mediated chemical reaction and electrochemical reactions in plasmonic junctions.•Electrochemical potential can regulate the competition between photo-oxidation and electrochemical reduction reactions.•Redox cycling between 4-ATP and its dimer DMAB is achieved in continuous electrode potential cycles under visible light.•The effect of electrochemical potential on the SERS spectral changes is separated to nonreaction and reaction mechanisms.