Scanning capillary microscopy/mass spectrometry for mapping spatial electrochemical activity of electrodes.

A new technique for microscopic imaging of electrochemically active surfaces is introduced. The technique combines concepts of probe microscopy and advances in mass spectrometry. The technique is based on a miniature electrochemical flow cell scanner. A liquid feed stream containing a redox component is introduced to the vicinity of the examined location through the annulus of a coaxial capillary set. The incoming reagent interacts with the target location, and the generated product stream is transferred through the inner capillary to an electrospray mass spectrometer, ESI-MS. Thus, a multicomponent, potential-dependent image of the products' distribution versus the location on the electrode is generated. The use of the technique is demonstrated by scanning the electrochemical heterogeneity of model electrodes.