Tuning of the spacing and thickness of metal latticeworks by modulation of self-organized potential oscillations in tin (Sn) electrodeposition

Potentiostatic current and galvanostatic potential oscillations during electrodeposition of cadmium

Cathodic current and potential oscillations were observed during electrodeposition of cadmium from a cyanide electrolyte on a vertical platinum electrode, in potentiostatic and galvanostatic experiments. Electrochemical impedance spectroscopy experiments revealed a region of negative real impedance in a range of non-zero frequencies, in the second descending branch with a positive slope of the N-shape current-potential curve. This kind of dynamical behaviour is characteristic of the HN-NDR oscillators (oscillators with the N-Shape current-potential curve and hidden negative differential resistance). The oscillations could be mainly attributed to the changes in the real active cathodic area, due to the adsorption of hydrogen molecules and their detachment from the surface. The instabilities of the electrochemical processes were characterized by time series, Fast Fourier Transforms and 2-D phase portraits showing quasi-periodic oscillations.

Oscillatory electrodeposition of metal films at liquid/liquid interfaces induced by the large surface energy of growing deposits

Electrodeposition of zinc (Zn) at an aqueous ZnSO4/n-butylacetate (BuAc) interface (liquid/liquid (LL) interface) showed a potential oscillation in the region of the current density exceeding the diffusion-limited one, accompanied by formation of two-dimensional Zn film with a concentric pattern at the LL interface. In-situ optical microscopic inspections revealed that the oscillatory growth of the Zn film synchronized with meniscus oscillation of the LL interface. The vigorous growth of the deposits occurs only when the shape of the meniscus becomes hollow on the negative potential side of the potential oscillation. On the other hand, on the positive side, the meniscus becomes almost flat and the deposits formed in the preceding stage are thickened. A mechanism is proposed to explain the oscillatory Zn electrodeposition coupled with the meniscus oscillation, on the basis of the fact that the interfacial tension at the growing metal/aqueous solution interface is extremely large.