Crossing VIMP and EIS for studying heterogeneous sets of copper/bronze coins

Abstract

Electrochemical impedance spectroscopy (EIS) and voltammetry of immobilized particles (VIMP) measurements using air-saturated mineral water and 0.10\xa0M NaClO4 aqueous solution as electrolytes were applied to eurocent coins and a set of copper/bronze coins from the late nineteenth century exhibiting significant heterogeneity in their degree and type of corrosion. The obtained data presented satisfactory repeatability being fitted to relatively simple equivalent circuits which were dependent on the electrolyte and bias potential, the more satisfactory conditions being obtained using the reduction of dissolved oxygen as a redox probe. Consistent data were obtained using VIMP and EIS characterizing different corrosion patterns, and establishing the possibility of discriminating different monetary emissions in favorable cases of high level of corrosion.