Characterization of corrosion products on contemporary bronze artwork by using voltammetry of microparticles and PCA

Voltammetry of Microparticles (VMP) is a solid-state electrochemical technique that has proven to be helpful in the examination of cultural heritage metallic objects. Herein, VMP procedure was firstly applied to the electrochemical characterization of standard bronze corrosion products, such as tenorite (CuO), cuprite (Cu2O) and gerhardtite (Cu2(NO3)(OH)3), among others. Once a library of electrochemical fingerprints had been created, the procedure was applied to the characterization of surface materials of the Warrior with Shield by Henry Moore. Principal component analysis was used in order to discriminate between different species displaying more or less similar electrochemical responses. Peak potential and peak current values from square-wave voltammetric scans were used together with other parameters (i.e. peak width, half-peak potential, onset potentials), including Tafel slopes and ordinates at the origin. The electrochemical measurements were compared to FT-IR and SEMS-EDS analyses.