Heterogeneity in metal dissolution reaction and passive film breakdown

Description:
Electrochemical metal dissolution reactions are fundamentally important in battery and corrosion processes. Their kinetics is highly dependent on surface structures and the presence of passive films. In this talk, I will present the study on the initiation of metal dissolution reactions on Ag and Ni, representing model systems for oxide-free and oxide-covered metals, respectively. The local dissolution kinetics is voltammetrically mapped via scanning electrochemical cell microscopy (SECCM). Co-localized characterization of crystal orientation reveals slower dissolution on {111} close-packed planes. The local dissolution kinetics on grain boundaries can also be directly measured, which shows a faster dissolution rate on some but not all grain boundaries. The dependence of passive film breakdown on the local electron transfer kinetics is obtained using outer-sphere redox molecules. Correlation between the local rate of electron transfer and susceptibility to breakdown is obtained. We demonstrate that correlative electrochemical and structural imaging are powerful tools for studying heterogeneity at complex electrochemical interfaces.

Speaker: Hang Ren - The University of Texas at Austin