Zusammenfassung
In the present report the well-known advantages of hydrodynamic mass transport in electrochemical systems are used in combination with scanning electrochemical microscopy (SECM). The hydrodynamic SECM system integrates a high-precision stirring device into the experimental setup. The well-defined stirring of the SECM electrolyte results in steady state diffusion layer characteristics in the ...
Zusammenfassung
In the present report the well-known advantages of hydrodynamic mass transport in electrochemical systems are used in combination with scanning electrochemical microscopy (SECM). The hydrodynamic SECM system integrates a high-precision stirring device into the experimental setup. The well-defined stirring of the SECM electrolyte results in steady state diffusion layer characteristics in the vicinity of large substrate electrodes operated in chronoamperometric measuring mode. For a range of rotation frequencies of a rotating cylinder the thickness and the stability of the diffusion layer was studied by hydrodynamic SECM in the substrate generation/tip collection (SG/TC) as well as in the competition mode using ferrocene methanol as redox mediator. Different UME probe dimensions ranging from Pt diameters of 20 mu m down to 0.6 mu m were used. The smallest probe with d(pt) = 0.6 mu m was found most suitable for these studies due to the almost convection-independent amperometric response associated with sub mu m electrodes. Additionally, preliminary studies of hydrodynamic SECM imaging of a 2 mm Pt disk electrode surface in the SG/TC mode based on in situ produced hydrogen as a mediator are presented. Comparative images measured in the conventional positive feedback mode in quiescent solution show that hydrodynamic SECM offers attractive complementary information.
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