Copper deposits obtained by pulsating overpotential regime with a long pause and pulse duration from sulfated solutions

The morphologies of the copper deposits obtained by pulsating overpotential regime with prolonged pulse and pause durations from the solution of 0.15 M CuSO4 in 0.50 M H2SO4 at overpotentials lower, higher and belonging to the plateau of limiting diffusion current density were compared with those obtained by the same electrodeposition regime from solutions of 0.075 and 0.30 M CuSO4 in 0.50 M H2SO4 and 0.15 M CuSO4 in 0.25 and 1.00 M H2SO4 at overpotentials outside the plateau of limiting diffusion current density. These samples were characterized by scanning electron microscopic (SEM) analysis and the cathodic polarization characteristics from solutions compared. Increasing the Cu(II) concentration led to an increase in the limiting diffusion current density. Decreasing the H2SO4 concentration shifts both beginning and the end of the plateau of the limiting diffusion current density towards higher electrodeposition overpotentials. Also, electrodeposition in solutions of 0.15 M CuSO4 in 0.25 and 1.00 M H2SO4 led to the formation of morphological forms of copper deposits characteristic for electrodeposition of copper from higher CuSO4 or lower H2SO4 in solution at some higher overpotentials.

Cross-section analysis of the morphology of electrodeposited copper obtained in the hydrogen co-deposition range

Cross-section analysis of copper deposits electrodeposited in the hydrogen co-deposition range at a constant overpotential and in a pulsating overpotential (PO) regime was performed. It was shown that a complete structural analysis of these technologically very important electrodes is impossible without an analysis of their internal structure. An insight into the compactness (or porosity) of the deposits, as well as into the depth of the holes, can only be obtained by this type of analysis.

Mass transfer during electrodeposition of metals at a periodically changing rate

1. Introduction 2. Mass transfer in the steady state periodic condition 2.1. Reversing current 2.2. Pulsating current 2.3. Alternating current superimposed on direct current 3. The influence of the charge and discharge of the electrical double layer 4. The validity of the mathematical model 4.1. Reversing current in the millisecond range 4.2. Reversing current in the second range 4.3. Pulsating current 4.4. Pulsating overpotential 5. Conclusion