Chapter 13
Preparation of Nanoporous Oxides
from Metals by Electrochemical
Anodization
13.1 Electrochemistry and High-Voltage Processes
Several processes have been discussed in the earlier chapters in which the total
cell voltage was unusually high (several tens of volts), which is clearly beyond the
potential difference scale that any cell with reversible electrodes in equilibrium may
produce. In spite of the relatively high cell voltage in the examples discussed earlier,
the electrode processes themselves could be elucidated with the classical terms of
electrochemical kinetics, i.e., with the exponential dependence of the reaction rate
constants on the electrode potential. In many cases, the large cell voltage was partly
due to the high cell resistance, mostly due to either the application of relatively dilute
solutions or small cross-sectional surface area of the cell.
The processes to be listed in Chaps. 13 and 14 have the common feature that
the elemental steps of the processes can hardly be described in terms of classical
electrochemical kinetics; i.e., the equations given in Chap. 2.8 cannot be taken valid.
In fact, the description of the impact chain of elemental processes is totally missing
in some cases. Hence, practically no quantitative analysis of these processes can
be given but one has to rely on experimental findings to correlate the technical
parameters of the sample preparation to the properties of the product.
Should these conditions seem to fall quite far from classical electrochemistry,
they fulfil the definition that some change in chemical state takes place as a result of
current applied. It is to be emphasized that in all processes presented in the present
and the next chapters, the nature of the current-induced chemical transformation is
highly specific, and no similar transformation can be achieved with any ancillary
effect of the high current passed through the system; for instance, the Joule heat of
the current alone would not lead to the same effect.
Two major process types are outlined in Part IV. The present chapter offers a
summary of metal anodization processes that lead to nanoporous structures. Chap. 14
will deal with electrical arc discharge processes resulting in nanostructure formation,
paying particular attention to various carbon nanostructures.
© 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_13
477
Preparation of Nanoporous Oxides
from Metals by Electrochemical
Anodization
13.1 Electrochemistry and High-Voltage Processes
Several processes have been discussed in the earlier chapters in which the total
cell voltage was unusually high (several tens of volts), which is clearly beyond the
potential difference scale that any cell with reversible electrodes in equilibrium may
produce. In spite of the relatively high cell voltage in the examples discussed earlier,
the electrode processes themselves could be elucidated with the classical terms of
electrochemical kinetics, i.e., with the exponential dependence of the reaction rate
constants on the electrode potential. In many cases, the large cell voltage was partly
due to the high cell resistance, mostly due to either the application of relatively dilute
solutions or small cross-sectional surface area of the cell.
The processes to be listed in Chaps. 13 and 14 have the common feature that
the elemental steps of the processes can hardly be described in terms of classical
electrochemical kinetics; i.e., the equations given in Chap. 2.8 cannot be taken valid.
In fact, the description of the impact chain of elemental processes is totally missing
in some cases. Hence, practically no quantitative analysis of these processes can
be given but one has to rely on experimental findings to correlate the technical
parameters of the sample preparation to the properties of the product.
Should these conditions seem to fall quite far from classical electrochemistry,
they fulfil the definition that some change in chemical state takes place as a result of
current applied. It is to be emphasized that in all processes presented in the present
and the next chapters, the nature of the current-induced chemical transformation is
highly specific, and no similar transformation can be achieved with any ancillary
effect of the high current passed through the system; for instance, the Joule heat of
the current alone would not lead to the same effect.
Two major process types are outlined in Part IV. The present chapter offers a
summary of metal anodization processes that lead to nanoporous structures. Chap. 14
will deal with electrical arc discharge processes resulting in nanostructure formation,
paying particular attention to various carbon nanostructures.
© 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_13
477