National Physical Laboratory

Local Electrochemical Techniques (Scanning Electrochemical Microscopy)

Scanning electrochemical microscopy contour map
Figure 1: Scanning electrochemical microscopy
contour map of a model proton exchange
membrane fuel cell catalyst film. The differing
colours relate to varying rates film activity towards
hydrogen oxidation.

While measurement techniques to characterise surface morphology, mechanical properties and chemistry at the micro- to nano-scale are comparatively well established, though under progressive evolution, measurement techniques to investigate the reactivity of surfaces, the kinetics of dynamic processes, and mass transport on a highly localised scale are still relatively in their infancy.

Scanning micro- and nano-probe electrochemical microscopy provides the basis for such local characterisation and is undergoing a rapid transition as it adapts to the many possibilities offered by developments in probe technology and associated instrumentation. The range of possible applications and the potential insights derived from electrochemical-scanning probe microscopy (e-SPM) are remarkable and relate to the capability for spatial mapping and quantification of local kinetics and transport. Investigations include molecular imaging, kinetics of enzyme activity, kinetics of homogeneous reactions and of heterogeneous reaction (corrosion, catalysis), imaging of molecular transport through pores in polymer and biological membranes, quantification of fluxes though pores, charge transfer at immiscible liquid-liquid interfaces, micro- and nano-patterning, electrochemical switching of molecular wires, and sensors. The range of innovative applications has continued to expand as the potential of e-SPM has become increasingly recognised.

NPL has a scanning electrochemical microscopy capability with a resolution in the order of micrometres (5-25 ┬Ám). In addition, research is under way to extend e-SPM measurements into the nanometre realm, principally by the development of nanometre sized electrodes, and to combine it with local structure measurement at the same scale. Measurements at modest temperatures (circa 60C) is also a current research aim. This research underpins NPL's current and future activities on fuel cells, photovoltaics, biomaterials and corrosion that require micro- and nano-scale characterisation of reactivity, transport processes and sensing capability.


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Last Updated: 5 Nov 2015
Created: 9 Jun 2009


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