Correlative Voltammetric Microscopy: Structure–Activity Relationships in the Microscopic Electrochemical Behavior of Screen Printed Carbon Electrodes
journal contributionposted on 2019-08-09, 11:33 authored by Daniel Martín-Yerga, Agustín Costa-García, Patrick R. Unwin
Screen-printed carbon electrodes (SPCEs) are widely used for electrochemical sensors. However, little is known about their electrochemical behavior at the microscopic level. In this work, we use voltammetric scanning electrochemical cell microscopy (SECCM), with dual-channel probes, to determine the microscopic factors governing the electrochemical response of SPCEs. SECCM cyclic voltammetry (CV) measurements are performed directly in hundreds of different locations of SPCEs, with high spatial resolution, using a submicrometer sized probe. Further, the localized electrode activity is spatially correlated to colocated surface structure information from scanning electron microscopy and micro-Raman spectroscopy. This approach is applied to two model electrochemical processes: hexaammineruthenium(III/II) ([Ru(NH3)6]3+/2+), a well-known outer-sphere redox couple, and dopamine (DA), which undergoes a more complex electron–proton coupled electro-oxidation, with complications from adsorption of both DA and side-products. The electrochemical reduction of [Ru(NH3)6]3+ proceeds fairly uniformly across the surface of SPCEs on the submicrometer scale. In contrast, DA electro-oxidation shows a strong dependence on the microstructure of the SPCE. By studying this process at different concentrations of DA, the relative contributions of (i) intrinsic electrode kinetics and (ii) adsorption of DA are elucidated in detail, as a function of local electrode character and surface structure. These studies provide major new insights on the electrochemical activity of SPCEs and further position voltammetric SECCM as a powerful technique for the electrochemical imaging of complex, heterogeneous, and topographically rough electrode surfaces.
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micro-Raman spectroscopymodel electrochemical processesposition voltammetric SECCMelectrochemical sensorsCarbon Electrodes Screen-printed carbon electrodesCorrelative Voltammetric Microscopysurface structureSPCEelectrode activityuse voltammetric scanning electrochemical cell microscopyelectrode surfaceselectrochemical activityelectrochemical responseouter-sphere redox couplescanning electron microscopyDA electro-oxidationelectrochemical imagingCVelectrochemical behaviorSECCM cyclic voltammetrycolocated surface structure informationelectrode characterelectrode kineticsMicroscopic Electrochemical Behaviorsubmicrometer scaleelectrochemical reduction