Nucleation and growth mechanism of cuprous oxide electrodeposited on ITO substrate

Abstract

The electrodeposition mechanisms of cuprous oxide (Cu2O) from copper nitrate solutions on indium tin oxide (ITO) were investigated using the cyclic voltammetry and the chronoamperometry methods. Then the kinetics parameters, nucleation and growth mechanism were explored. The CV measurement showed that the electrodeposition of Cu2O takes place by cathodic reduction at potential −0.5 V versus saturated calomel electrode (SCE). Furthermore, the voltammograms at different scan rates revealed that the electrodeposition reaction of Cu2O is a quasi-reversible reaction controlled by the diffusion of copper ions. Moreover, the deposition mechanism of Cu2O on the ITO substrate determined by the Astley approach and confirmed by the Scharifker-Hills models follows an instantaneous three-dimensional (3D) nucleation controlled by diffusion with an average diffusion coefficient D of 0.549 10-6 cm2 s−1. The X-ray diffraction pattern of Cu2O film was indexed to cubic crystal structure. The scanning electron microscopy analysis indicated that the average size of the cuprous oxide particles is about 1.408 µm. The optical energy band gap (Eg) was calculated by Tauc’s plot for Cu2O is 2.16 eV. The theoretical analyses reveal that Cu2O has an energy band gap of 2.25 eV, which corresponds to experimental results.