Scanning Electrochemical Cell Microscopy; Measurement Process Optimization to the Electrochemical Response Based on Experimental Parameters

Abstract

As the development of scanning probe microscopy (SPM) continues, the spatial resolution and sensitivity for various material properties steadily improve. Therefore, SPM images morphological features as well as electrical, mechanical, magnetic, and chemical properties with a nanoscale resolution. Among the various SPM techniques, pipette-based SPM offers new possibilities and insights into the sample’s electrochemical properties. Since the invention of scanning electrochemical microscopy (SECM), the first-generation pipette-based SPM for electrochemical measurement, it has been extensively used in many research fields, e.g. for visualizing chemical reactions at surfaces and interfaces. However, the difficult distance control between the pipette probe and the sample surface limits the application of SECM.Here, we introduce scanning electrochemical cell microscopy (SECCM): a latest pipette-based SPM method, which investigates electrochemical responses on target materials in a point-by-point approach using the ionic current for distance control. We present experimental and theoretical data on contributing factors to the electrochemical response, including pipette configuration, redox species, scan rate and choice of substrate. A variety of pipette inner diameters (range from ~150 nm to ~ 1 μm), buffer concentrations, and voltammetric sweep rates are reviewed using well-defined conductive substrates and electrodes. Based on our results, we propose optimized experimental parameters for various measurement conditions. We believe that SECCM has great potential in providing new insights to electrochemical properties of surfaces and interfaces required for research on chemical energy storage, among others. Figure 1