Fabrication of Cu₂O Nanostructured Thin Film by Anodizing

Cuprous oxide, a narrow bandgap p-type semiconductor, has been known as a potential material for applications in supercapacitors, hydrogen production, sensors, and energy conversion due to its properties such as non-toxicity, easy availability, cost effectiveness, high absorption coefficient in the visible region and large minority carriers diffusion length. In this study, Cu₂O nanostructured thin film was fabricated by anodizing of Cu plates in ethylene glycol containing 0.15 M KOH, 0.1 M NH₄F and 3 wt.% deionized water. The effects of anodizing voltage and temperature of electrolyte were investigated and reported. It was found that nanoporous Cu₂O thin film was formed when anodizing voltages of 50 V and 70 V were used while a dense Cu₂O thin film was formed due to the aggregation of smaller nanoparticles when 30 V anodizing voltage was used. Nanoplatelets thin film was formed when the temperature of electrolyte was reduced to 15 °C and 5 °C. X-ray diffraction confirmed the presence of Cu₂O phase in thin film formed during anodizing of Cu plates, regardless of the anodizing voltage and temperature of electrolyte. Photoluminescence spectroscopy showed the presence of Cu₂O peak at 630 nm corresponding to band gap of 1.97 eV. A mechanism of the formation of Cu₂O thin film was proposed. This study reported the ease of tailoring Cu₂O nanostructures of different morphologies using anodizing that may help widen the applications of this material