Scanning Electrochemical Microscopy

Abstract Scanning electrochemical microscopy (SECM) involves the measurement of current through an ultramicroelectrode (UME) tip when it is held or moved in a solution in the vicinity of a substrate. The substrate perturbs the electrochemical response of the tip, and this perturbation provides information about the nature and properties of the substrate. SECM has the advantage of very high spatial resolution and versatility for the detection of both electroactive and nonelectroactive species. It combines the virtues of electrochemistry at UMEs with those of an adjustable thin‐layer cell and allows one to make steady‐state measurements of the type carried out with the rotating ring‐disk electrode (RRDE), but with greater ease in fabrication, comparable rates of mass transfer, and without the requirement of forced convection. SECM has been applied to studies involving many different kinds of systems including electrode surfaces, liquid–liquid interfaces, and biological samples with micrometer and nanometer resolution. Commercial SECM systems exist, which facilitate such investigations.