Nanoelectrodes, scanning electrochemical

Nanoelectrodes in SECM — For the improvement of the lateral resolution in - scanning electrochemical microscopy (SECM) the size of the - ultramicro electrode... 

Hussien EM, Schuhmarm W, Schulte A (2010) Shearforce-based constant-distance scanning electrochemical microscopy as fabrication tool for needle-type carbon-fiber nanoelectrodes. Anal Chem 82(13) 5900-5905... 

Kranz C (2014) Recent advancements in nanoelectrodes and nanopipettes used in combined scanning electrochemical microscopy techniques. Analyst 139 336-352... 

Yamada, H., D. Haraguchi, and K. Yasunaga, Fabrication and characterization of a K+-selective nanoelectrode and simultaneous imaging of topography and local K+ flux using scanning electrochemical microscopy, Anal. Chem., Vol. 86, 2014 pp. 8547-8552. 

Other applications snch as the measuranent of local concentrations in environmental analy-sis44,45 using potentiometric probes as detectors in various types of scanning electrochemical microscopies inclnding probes with dnal functionality are emerging, but are stiU largely limited to micrometer-size electrodes due to inherent difficulties of using nanoelectrodes. 

B.B. Katemann, A. Schulte, W. Schuhmann. Constant-distance mode scanning electrochemical microscopy. Part II High-resolution SECM imaging employing Pt nanoelectrodes as miniaturized scanning probes. Electroanalysis 16 60 (2004). 

Etienne, M., Anderson, E. C., Evans, S. R., Schuhmann, W., Eritsch, 1., Eeedback-independent Pt nanoelectrodes for shear force-based constant-distance mode scanning electrochemical microscopy. Anal. Chem. 2006, 78, 7317-7324. 

For slow scan rates, i.e., a few volts per second or slower, the voltammetric response of a miniaturized electrode is a sigmoid-shaped steady-state voltammogram [8]. Peak-shaped responses are observed (Mily when the scan rate is sufficiently high so that the depletion layer thickness is smaller than the critical dimension of the electrode. For example, a 50-nm-radius nanoelectrode requires the sweep rate to be of the order of 10,000 Vs to show the classical peak-shaped responses typically observed for electrochemically reversible systems at macroelectrodes at mVs scan rates. The theory describing mass transport to micro- and... 

The essence of SECM is bringing a small electrode, i.e., micro- or nanoelectrode, close to an interface while recording its faradic current, fii most cases the solution consists of one state of a redox couple that is being oxidized or reduced at the microelectrode. A typical setup of SECM is shown in Fig. 1. Once the interface enters the diffusion layer of the microelectrode, the latter can laterally scan the interface to obtain topographical and electrochemical information. Several modes of operation of SECM have been... 

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