Nucleation and Film Growth on the Electrochemical Deposition of Cu₂O/CuO Heterostructures on Carbon Cloth: I. Effect of Deposition Temperature

In this work, Cu₂O/CuO coating nanostructured coatings were electrodeposited on carbon cloth substrates, and the influence of deposition temperature on nucleation behavior, structural properties, and electrochemical performance was systematically investigated. The electrodeposition process was carried out in a lactate-based electrolyte containing CuSO₄·5H₂O at pH 9, while the bath temperature was varied between 50 and 70 °C. Cyclic voltammetry revealed temperature-dependent reduction processes associated with Cu²⁺/Cu⁺ conversion and Cu₂O/CuO formation. Chronoamperometric studies combined with the Scharifker–Hills model demonstrated that growth follows a three-dimensional instantaneous nucleation mechanism governed by diffusion. Increasing the deposition temperature enhanced the diffusion coefficient and film thickness, indicating improved ion transport and accelerated nucleation kinetics. Structural characterization by XRD confirmed that the deposited nanostructures mainly consist of crystalline Cu₂O/CuO with minor contributions from Cu(OH)₂ phase, while SEM revealed a strong dependence of surface morphology on temperature. A highly uniform and compact nanostructured coating was obtained at 65 °C, which also corresponded to the highest crystallinity. Mott–Schottky analysis indicated p-type semiconductor behavior with carrier densities in the order of 10¹⁸–10¹⁹ cm⁻³. The optimized Cu₂O/CuO/CC heterostructure obtained at 65 °C shows promising characteristics for electrochemical and photoelectrochemical applications.