Development of Integrated Scanning Electrochemical Cell Microspectroscopy for Characterization of Redox and Reactive Electrochemistry

Abstract

Understanding molecular-level transformations resulting from electrochemical reactions is important for designing efficient and reliable systems for energy conversion and storage. In this work, an integrated scanning electrochemical cell microspectroscopy (iSECCMS) platform is developed by combining a high spatial resolution electrochemical scanning probe technique with in situ ultraviolet visible (UV-VIS) absorption/fluorescence spectroscopy. The iSECCMS platform is used for spatially-resolved characterization of electrochemically-active redox systems and the results are compared to those obtained with conventional ex situ 3-electrode electrochemical measurements to establish the reliability of the technique. Using 6- carboxyfluorescein as a fluorescent probe, the iSECCMS platform is employed to measure the effect of detrimental generation of reactive oxygen species (ROS)/H2O2 on the active sites for the oxygen reduction reaction (ORR). Carbon-supported tantalum-doped titanium oxide catalysts, a cathode employed in low temperature polymer electrolyte fuel cells (PEFCs), are examined as a model system. We establish that the iSECCMS platform provides an opportunity for spatially-resolved mapping of both electrochemical activity and capture transient intermediate species (e.g. ROS) in functional electrochemical interface.