Study of Charge Accumulation and Kinetic Reactions on Copper Electrodes Surfaces by Electrochemical and Optical Polarization Techniques

Abstract

Understanding surface and interface processes at the atomic level occurring in metals with a crystalline structure are of scienti c and technological relevances. Especially in electrochemical environments, metal surfaces play a crucial role whose primary interest lies in the physical-chemical phenomena fundamentals. Moreover, a precise knowledge of atomically controlled interfaces can be extended to cases stemming from amorphous or polycrystalline composites as in the majority of industrial applications; such as in renewable energies, pharmaceuticals, and petrochemical, to name a few. The study undertaken in this thesis tackles fundamental issues on the electronic processes taking place in both copper (110) and (111) surfaces in electrochemical environments based on hydrochloric acid (HCl) and the forming Helmholtz double layer. This study was carried out using two linear optical spectroscopies, namely re ectance anisotropy (RAS-RDS) and ellipsometry (SE), both operating in-situ and real-time and in the spectroscopic mode as well. Simultaneously, measurements based on cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chrono-amperometry (CA) were also performed. Clear correlations were found among the aforementioned techniques. The outline can be summarized as i) in-depth adsorbate Frumkin (Flori-Huggins) isotherm analysis by RAS on Cu (110) in HCl, (ii) observation of HCl-induced surface states at di erent potentials and their correlation with electrochemical scanning tunneling microscopy (EC-STM), and (iii) a study regarding the evolution of Cl������� adsorption process using CA and SE, for both (111) and (110) surfaces. This thesis reports for the rst time, at least for the authors knowledge, a systematic optical and electrochemical study of Cu(110) and Cu(111) with several experimental tools, rendering RAS and SE as complementary probes for analytical studies in electrochemical processes.