Scanning Electrochemical Cell Microscopy: Theory and Experiment for Quantitative High Resolution Spatially-Resolved Voltammetry and Simultaneous Ion-Conductance Measurements
- 17 February 2012
- journal article
- research article
- Published by American Chemical Society (ACS) in Analytical Chemistry
- Vol. 84 (5), 2483-2491
- https://doi.org/10.1021/ac203195h
Abstract
Scanning electrochemical cell microscopy (SECCM) is a high resolution electrochemical scanning probe technique that employs a dual-barrel theta pipet probe containing electrolyte solution and quasi-reference counter electrodes (QRCE) in each barrel. A thin layer of electrolyte protruding from the tip of the pipet ensures that a gentle meniscus contact is made with a substrate surface, which defines the active surface area of an electrochemical cell. The substrate can be an electrical conductor, semiconductor, or insulator. The main focus here is on the general case where the substrate is a working electrode, and both ion-conductance measurements between the QRCEs in the two barrels and voltammetric/amperometric measurements at the substrate can be made simultaneously. In usual practice, a small perpendicular oscillation of the probe with respect to the substrate is employed, so that an alternating conductance current (ac) develops, due to the change in the dimensions of the electrolyte contact (and hence resistance), as well as the direct conductance current (dc). It is shown that the dc current can be predicted for a fixed probe by solving the Nernst-Planck equation and that the ac response can also be derived from this response. Both responses are shown to agree well with experiment. It is found that the pipet geometry plays an important role in controlling the dc conductance current and that this is easily measured by microscopy. A key feature of SECCM is that mass transport to the substrate surface is by diffusion and, for charged analytes, ion migration which can be controlled and varied quantifiably via the bias between the two QRCEs. For a working electrode substrate this means that charged redox-active analytes can be transported to the electrode/solution interface in a well-defined and controllable manner and that relatively fast heterogeneous electron transfer kinetics can be studied. The factors controlling the voltammetric response are determined by both simulation and experiment. Experiments demonstrate the realization of simultaneous quantitative voltammetric and ion conductance measurements and also identify a general rule of thumb that the surface contacted by electrolyte is of the order of the pipet probe dimensions.Keywords
This publication has 59 references indexed in Scilit:
- Single-Nanopore Investigations with Ion Conductance MicroscopyACS Nano, 2011
- Visualizing Zeptomole (Electro)Catalysis at Single Nanoparticles within an EnsembleJournal of the American Chemical Society, 2011
- Localized High Resolution Electrochemistry and Multifunctional Imaging: Scanning Electrochemical Cell MicroscopyAnalytical Chemistry, 2010
- Electron Transfer Kinetics at Single-Walled Carbon Nanotube Electrodes using Scanning Electrochemical MicroscopyThe Journal of Physical Chemistry C, 2010
- Interrogation of living cells using alternating current scanning electrochemical microscopy (AC-SECM)Physical Chemistry Chemical Physics, 2007
- Imaging Proteins in Membranes of Living Cells by High‐Resolution Scanning Ion Conductance MicroscopyAngewandte Chemie, 2006
- Application of AC impedance techniques to Scanning Electrochemical MicroscopyJournal of Solid State Electrochemistry, 2004
- Precursor sites for localised corrosion on lacquered tinplates visualised by means of alternating current scanning electrochemical microscopyElectrochimica Acta, 2003
- Capillary-based droplet cells: limits and new aspectsElectrochimica Acta, 2001
- The scanning droplet cell and its application to structured nanometer oxide films on aluminiumElectrochimica Acta, 1997