Effect of chloride and pH on the electrochemical surface oxidation enhanced Raman scattering

Abstract In the present work, electrochemical surface oxidation enhanced Raman scattering (EC-SOERS) was studied using time resolved Raman spectroelectrochemistry. This multiresponse technique allows us to obtain dynamic information about the processes taking place during the electrochemical oxidation of a silver substrate. EC-SOERS is particularly found in specific electrolytic conditions, namely, HClO 4 0.1 M + KCl 5·10 −3 M, and has a clear dependence on chloride concentration and pH, being the optimum values between 5·10 −3 M and 1·10 −2 M for chloride and pH = 1. In light of the results of this study, the appearance of the phenomenon is related to the modification of the electrode surface, yielding Ag/AgCl cubes as plasmonic structures, and the stability of such structures at low pH values. The results presented in this work could shed more light into the intricate EC-SOERS phenomenon which can be summarized as the increase of the Raman signal for a Raman probe molecule exclusively during the electrochemical oxidation of silver electrodes.