Mechanism of electrodeposition and dissolution processes of copper in aqueous solutions

Abstract

Kinetic studies on the short time deposition and dissolution of copper in solutions of cupric sulphate, chloride, perchlorate, acetate and aminosulphonate, and their corresponding acids, were carried out by means of a galvanostatic transient method at 30°C, using electrodes prepared by melting in helium (A-type) or by electrodeposition @-type).Tafel relations were observed on B-type electrodes (&a 120 and b a ~ 40 mv). Overpotentialtime transients indicated deviations from a simple double-layer charging model, and these were greatest on A-type electrodes. 3 In i0/3 In a c u z + ~0 -5 ; anion effects increased with increasing size of the ions.Two rate-determining steps are assumed under specific conditions : surfaw diffusion when the surface has a relatively low number of surface dislocations, and charge transfer, Cu2++e-+Cu+, respectively. The number of growth sites is calculated. A-type electrode$ have a lesser dislocation density than B-type. The transfer reaction suggested is consistent with the large rise time of overpotential on B-type electrodes, because electricity is needed to equilibrate the " fast ,' step Cu++e+Cu. The concentration dependence of io is interpreted in terms of an increasing rate-controlling influence of the Cu++e+Cu step at the highest concentrations. The asymmetric i against 7 relation observed on A-type electrodes depends on an approach to saturation (with adions) of the electrode surface. Differences of io for the transfer reaction on A and B electrodes are due to secondary causes, e.g., surfaces of A electrodes spend less time ia contact with solution. Anion effects u e consistent with a simple blocking of sites by specifically adsorbed anions.Deposition and dissolution at the Cu/aq. CuSO4, H2S04 interface was studied by Mattsson and Bockris.* The galvanostatic transient studies reported here are concerned with the dependence of the velocity of the metal-solution exchange reaction on metal ion concentration and anions present in solution. EXPERIMENTAL APPARATUSThe cell used was similar to that reported elsewhere.l.2 Air was removed by purzed helium.3 The traps with active charcoal used in gas purification were heated frequently. The cell was thermostatted at 30f03"C. ELECTRODESThese were prepared and used as reported 1 9 4 (spectroscopically pure). The electrodes attained reversible potential in a short time after they were immersed in the solution and their glass sheaths broken. A glass tube covered the wire connecting the spherical electrode to the holder. The reference electrode was a copper Wire.

Copper Electrodeposition Kinetics Measured by Alternating Current Voltammetry and the Role of Ferrous Species

“…Of the two electron transfer steps involved in copper reduction, the first (reaction 3) is reported as rate-limiting. 12,13 Under certain conditions, such as near neutral pH electrolytes, copper electroreduction signals only exhibit one electron transfer event.…”

Inhibiting action of α‐pyrophthalone in copper corrosion

“…It is known from the literature data that the copper corrosion in weakly acid and nearly neutral solutions is determined in the initial steps by the reactions: (1 b) is the rate determining step [16] and shows usually a Tafel slope of 40 eV.…”

Deposition and Dissolution of Metals and Alloys. Part B: Mechanisms, Kinetics, Texture, and Morphology

“…The pseudocapacitance determinations from galvanostatic transient analysis in the case of copper were first carried out by Bockris and Enyo (27); values of the order of 100 #LF cm-2 were found.…”