Electrochimica Acta, Vol.197, 318-329, 2016
Combined detection of electrochemical reactions and topographical effects - imaging with scanning ohmic microscopy
The ohmic principle for the detection of local current densities with capillary-based microreference electrodes was used for reactivity imaging. Specifically, reactions of adlayers and ion-intercalation and ion deintercalation reactions were imaged that are not directly visible to other electrochemical imaging methods such as scanning electrochemical microscopy. The microreference electrodes were inclined by 45 degrees vs. the surface normal. During the scanning process, cyclic voltammograms (CVs) were performed at each grid point of the image while the voltage between the two reference electrodes was recorded and processed by a lock-in-amplifier. Images of specific electrochemical reaction rates were generated by integration of the corresponding data segments within the CVs. The setup was coupled with a shear force distance control to correlate the electrochemical reactivity with topographical data. The results clearly show that processes like adsorption and intercalation reactions, invisible to SECM, can be imaged by scanning ohmic microscopy with a resolution in the low micrometer range. (C) 2015 Elsevier Ltd. All rights reserved.
Keywords:scanning ohmic microscopy;reactivity imaging;scanning electrochemical microscopy;adlayer formation;ion intercalation;microelectrode arrays;Prussian Blue