Dish-like holes

Figure 28. Copper deposits obtained at an overpotential of 1,000 mV from 0.60 M CUSO4 in 0.50 M H2 SO4 (a) dish-like holes, (b) the bottom, and (c) the wall of the dish-like hole, and (d) dendrite formed between holes. Quantity of the electricity 2.5 mAh cm-2. (Reprinted from Ref. 58 with permission from Elsevier).

The electrodeposition processes at an overpotential of 1,000 mV from 0.60 M Q1SO4 in O.5OMH2SO4 led to the formation of dishlike holes only. The typical dish-like holes formed with the quantity of the electricity of 2.5 mAh cm-2 are shown in Fig. 28a, from which it can be seen that copper dendrites were formed at their... 

On the basis of the presented analysis of the electrodeposition processes at an overpotential of 1,000 mV (Figs. 26-28), it is obvious that increasing the concentration of Cu(II) ions leads to a change in the shape of the holes from those forming a honeycomb-like structure to dish-like holes. 

Dish-like holes were formed from the more concentrated solution (0.60 MCUSO4 in 0.50 M H2SO4), accompanied by a considerably lower quantity of evolved hydrogen (jjav(I h) = 4.6%) than was the case with the holes forming a honeycomb-like structure (0.075 M and 0.15 M Q1SO4 in 0.50 M H2S04). 

The acceleration of electrochemical processes through the increase of concentration of Cu(II) ions above 0.15M CuSC>4 (in 0.50 M H2SO4) showed an unfavorable effect to the formation of the honeycomb-like structure due to the formation of dish-like holes with the higher concentrations of Cu(II) ions.58... 

Nikolic ND, Pavlovic LjJ, Pavlovic MG, Popov KI (2007) Formation of dish-like holes and a channel structure in electrodeposition of copper tmder hydrogen co-deposition. Electrochim Acta 52 8096-8104... 

I) The range of the average current efficiencies of hydrogen evolution, 7i,av(H2), between 0 and 10.0%—the dominant presence of branchy dendrites, independently formed cauliflower-like forms, and the possible formation of individual holes of detached hydrogen bubbles (dish-like hole) [30, 31, 38, 41]. 

The concentration of 0.30 M CUSO4 (in 0.50 M H2SO4) is the transitional concentration between lower and higher concentrations of Cu(ll) ions. The mixture of holes forming the honeycomb-like structure and dish-like holes was obtained by electrodeposition from this solution at an overpotential of 1,000 mV (Fig. 4.6) [19]. 

Using7a of 0.44 A/cm, the honeycomb-like structures are formed with deposition pulses of 7 ms and longer and the typical honeycomb-like structure obtained with a deposition pulse of 10 ms is shown in Fig. 4.20a. The mixture of dish-like holes and holes constructing the honeycomb-like structure was formed with a deposition pulse of 4 ms (Fig. 4.20b). Finally, as already mentioned, dishlike holes and independently formed agglomerates of copper grains were formed with a deposition pulse of 1 ms (Fig. 4.19b). 

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