Modification of Electrode Surfaces by In Situ STM

In the following section, we focus on imaging single-crystal electrode surfaces that are of relevance to electrocatalysis. We will first deal with flat, defect-free terraces as well as with more real surfaces with monoatomic high steps as the most common active sites. We will then explore various strategies for nano structuring surfaces, for example, by repetitive oxidation-reduction cycles (ORCs). 

Soon after the invention of the STM as a tool for imaging surfaces in real space, it was discovered that the microscope could also be used (or misused) for surface manipulations, that is, for nano structuring of surfaces [5]. The extremely close vicinity of the STM tip and the sample surface required by the tunnel process 

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Lithography With the STM Electrochemical Techniques. The nonuniform current density distribution generated by an STM tip has also been exploited for electrochemical surface modification schemes. These applications are treated in this paper as distinct from true in situ STM imaging because the electrochemical modification of a substrate does not a priori necessitate subsequent imaging with the STM. To date, all electrochemical modification experiments in which the tip has served as the counter electrode, the STM has been operated in a two-electrode mode, with the substrate surface acting as the working electrode. The tip-sample bias is typically adjusted to drive electrochemical reactions at both the sample surface and the STM tip. Because it has as yet been impossible to maintain feedback control of the z-piezo (tip-substrate distance) in the presence of significant faradaic current (vide infra), all electrochemical STM modification experiments to date have been performed in the absence of such feedback control. 

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