Porous structure copper foam

One is the porous structure of foam wall. The wall of copper electro-deposits includes a number of small pores between branches, as seen in Fig. 4(b), whereas that of tin electro-deposits shows little pores inside, as seen in Fig. 6(b). As discussed earlier, hydrogen gas plays a critical role, as a dynamic template, in forming porous structure. In the course of copper deposition, hydrogen gas... 

Shin, H. C., and Liu, M. L. (2004]. Copper foam structures with highly porous nanostructured walls, Chem. Mater., 16, pp. 5460-5464. 

In order to increase the specific surface area and enhance the effectiveness/ activity of the porous electrodes, it is necessary to reduce the size of the pores, as well as the branches in the foam or agglomerates of copper grains in the honeycomb-Uke structures [26]. One of the ways to improve micro- and nanostructural characteristics of open porous electrodes is the addition of additives to the electroplating solution [26]. The decrease of diameter of holes, as well as the increase of their number in 3D foam copper structures, can be realized by the addition of acetic acid to the copper sulfate solution [26]. Also, the addition of chloride ions dramatically reduces the size of the copper branches in the walls of holes. The reduction in pore size is a result of lowering hydrophobic force of the generated hydrogen gas by adding bubble stabilizer (e.g., acetic acid) that suppresses the coalescence of bubbles, while the decrease in branch size in the foam wall is a consequence of the catalytic effect of chloride ions on the copper deposition reaction. 

To increase the specific surface area and enhance the effectiveness/ activity of the porous electrodes, it is necessary to reduce the size of the pores, as well as the branches in the foam or agglomerates of copper grains in the honeycomb-like structures [4]. 

Since tin is apt to grow dendritically dnring the electrochemical deposition, tin electro-deposit is very likely to have a porous wall similar to 3-D copper. Shown in Fig. 6 are some typical tin electro-deposits at a cathodic current density of 3 A cm in the electrolyte solution of 1 M sulfuric acid + 0.15 M tin sulfate. The overall foam structure is nearly identical to that of copper. 

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