Ring-disk microelectrodes for simultaneous constant-distance and constant-current mode scanning electrochemical microscopy

Ring-disk microelectrodes are proposed to be applied in a double constant-current mode using simultaneously an irreversible and a reversible reaction at the SECM tip. This allows an independent determination of the tip-to-sample distance concomitantly with the visualization of the lateral electrochemical reactivity of the investigated sample surface. The principle feasibility is demonstrated using a large and topographically as well as electrochemically challenging model sample.

► Constant-current mode for the investigation of topography and electrochemical activity.
► Utilization of a reversible and irreversible redox species.
► Ring-disk electrodes for the independent detection of two different redox mediators.
► Constant-distance mode for large surface areas.