Electrochemical oscillatory behavior under a scanning electrochemical microscopic configuration

Abstract

Diffusion coupled oscillatory behavior of the Au|HCI system was investigated in the presence of substrate “feedback” of the scanning electrochemical microscopic (SECM) system. It is shown that the amplitude of current oscillation can be increased significantly with a slight decrease in the oscillation frequency when the Pt substrate is positioned close to the small Au oscillating electrode. Such a “feedback” effect of the substrate may also become the driving force to induce current oscillation at the potential where normally electrodissolution occurs. The use of SECM to distinguish the types of oscillation mechanism of chosen systems is demonstrated by further fulfillment of a similar experiment on the surface process controlled potential oscillation system of Pt|HCHO. For this purpose, a special home-made galvanostat-potentiostat was employed which is generally necessary for studies of surface process controlled oscillation and may also be useful for studies of diffusion coupled oscillation under current control. It is shown that such an investigation under SECM configuration may provide insight into the oscillatory behavior from a new point of view.