RGB video electrochemistry of copper electrodeposition/electrodissolution in acid media on a ternary graphite:copper:polypropylene composite electrode

Highlights: • Spectroelectrochemical information of the whole surface is acquired at each time. • Ohmic drop effect on the electrodeposition is measured by color changes. • The profile of covering fraction is obtained at each time by measuring color intensity. • Peaks of standard deviation of the surface are associated to the growth of new layers. -- Abstract: Galvanostatic copper electrodeposition and electrodissolution on graphite:copper:polypropylene composite electrodes in acidic media have been investigated to extend the technological applicability of ternary composites. Both electrochemical processes were monitored by RGB video electrochemistry. The analysis of digital images allowed the color changes on the electrode surface to be investigated. We estimate the growth rate of the copper layer in two different electrode geometries. The relatively high resistance of this composite causes a gradient of the electric resistance along the electrode involving a non-homogeneous electrodeposit growth in CuSO₄/H₂SO₄ aqueous solutions. Copper electrodissolution was studied in HCl and H₂SO₄ aqueous solutions. Whereas chloride anions stabilized cuprous cation, the electrodissolution process in HCl takes place apparently by a more complicated mechanism. Dispersion of color estimated from the standard deviation of the RGB color images was also analyzed and it has been postulated as a tool for identifying possible intermediate species on the electrode surface.