Chapter 12
Localized or Spatially Selective
Electrodeposition Methods
12.1 Electrodeposition in Ultrathin Solution Layers Along
the Edge of the Cell
12.1.1 Transport and Fluid Motion in Thin-Layer Cells
of Various Orientations
A correct view of the transport phenomena in thin-layer electrochemical cells is
essential to understand the processes taking place and the growth dynamics of
deposits forming therein. Below, a short summary is devoted to this topic for underpinning the forthcoming sections. This overview is restricted to the case when the
current in the cell (and, hence, the direction of the growth) is parallel to the solution
layer plane. The two basic possible arrangements are the horizontal and the vertical
solution layers, which terms also refer to the current direction. The electrodes fill the
entire cell cross section horizontally along the edge of the cell at the initial phase of
the deposition in the case of both arrangements. It is also common in the two cases
that, in addition to the concentration gradient, a density gradient (which is, in turn,
proportional to the concentration gradient in the first approximation) may lead to a
gravity-induced convection.
In horizontal thin-layer cells, it is very tempting to treat the transport as a onedimensional diffusion and migration problem. It has long been recognized that this
one-dimensional treatment is not necessarily acceptable [1]. The conclusion of the
above-mentioned work is summarized here shortly. It has been shown that two distinct
regimes may be present, depending on the relative rates of the horizontal expansion of
the diffusion field and gravity-induced convection. The latter effect modifies the horizontal composition gradient to a tilted or vertical one by a circular flow of the solution
within the cell. It was shown that, after applying the current, convection should first
appear. This period was called the “immiscible-fluid regime”, indicating that the alleviation of the concentrations due to diffusion was negligible. The immiscible-fluid
regime is present to layer thicknesses down to 70 µm. The circular gravity-induced
© Springer Nature Switzerland AG 2021
L. Péter, Electrochemical Methods of Nanostructure Preparation,
Monographs in Electrochemistry, https://doi.org/10.1007/978-3-030-69117-2_12
423
Localized or Spatially Selective
Electrodeposition Methods
12.1 Electrodeposition in Ultrathin Solution Layers Along
the Edge of the Cell
12.1.1 Transport and Fluid Motion in Thin-Layer Cells
of Various Orientations
A correct view of the transport phenomena in thin-layer electrochemical cells is
essential to understand the processes taking place and the growth dynamics of
deposits forming therein. Below, a short summary is devoted to this topic for underpinning the forthcoming sections. This overview is restricted to the case when the
current in the cell (and, hence, the direction of the growth) is parallel to the solution
layer plane. The two basic possible arrangements are the horizontal and the vertical
solution layers, which terms also refer to the current direction. The electrodes fill the
entire cell cross section horizontally along the edge of the cell at the initial phase of
the deposition in the case of both arrangements. It is also common in the two cases
that, in addition to the concentration gradient, a density gradient (which is, in turn,
proportional to the concentration gradient in the first approximation) may lead to a
gravity-induced convection.
In horizontal thin-layer cells, it is very tempting to treat the transport as a onedimensional diffusion and migration problem. It has long been recognized that this
one-dimensional treatment is not necessarily acceptable [1]. The conclusion of the
above-mentioned work is summarized here shortly. It has been shown that two distinct
regimes may be present, depending on the relative rates of the horizontal expansion of
the diffusion field and gravity-induced convection. The latter effect modifies the horizontal composition gradient to a tilted or vertical one by a circular flow of the solution
within the cell. It was shown that, after applying the current, convection should first
appear. This period was called the “immiscible-fluid regime”, indicating that the alleviation of the concentrations due to diffusion was negligible. The immiscible-fluid
regime is present to layer thicknesses down to 70 µm. The circular gravity-induced
© Springer Nature Switzerland AG 2021
L. Péter, Electrochemical Methods of Nanostructure Preparation,
Monographs in Electrochemistry, https://doi.org/10.1007/978-3-030-69117-2_12
423