Chemija / Chemistry
 ISSN 0235-7216 ISSN 2424-4538 (online) |
2015 m. Nr. 4 The initial stages of copper deposition onto glassy carbon electrode modified with selenium compounds
The initial stages of Cu deposition onto unmodified and modified GC electrodes with selenium compounds were investigated in a 0.5 M H2SO4 + 0.01 M CuSO4 solution over a wide range of potentials, covering both underpotential and overpotential regions. The electrochemical techniques, such as cyclic voltammetry and chronoamperometry along with structural investigation like scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and ex situ atomic force microscopy (AFM), were applied to study the nucleation and growth of Cu onto a GC electrode. On the basis of analysis of the potentiostatic current transients, it has been shown that in the potential region where Cu underpotential deposition (UPD) onto a foreign substrate is usually observed, the initial stages of Cu electrocrystallization onto the GC electrode modified with selenium compounds quite well fit the instantaneous 2D nucleation and growth model developed by Bewick et al. In the overpotential region (OPD) Cu deposition was shown to proceed by the instantaneous 3D nucleation and diffusion-controlled growth model developed by Scharifker and Hills on both the unmodified and modified with selenium compounds GC electrodes. Meanwhile, in the OPD region two successive peaked segments with the characteristic current maxima (M1 and M2) in the transients for Cu deposition onto the Se-modified GC electrode indicating some complex nucleation and growth process were determined. Some morphologic characteristics have been discussed.
Keywords: copper, glassy carbon electrode, Se-modified gl |
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