In order to obtain inexpensive and effective application of catalyst for photodegradation, Cu₂O powder was prepared by the simple and inexpensive electrodeposition method using surfactants such as glycerin (GLY), polyvinyl alcohol (PVA), poly(N-vinylpyrrolidone) (PVP) that helped the growth and nucleation of suspended particles. These particles were distinguished by atomic force microscopy (AFM), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). Diameter size of these obtained particles was found to reach to about 40 nm. In order to demonstrate the photodegradation efficiency of the copper oxide in the removal of organic malachite green oxalate (MG) dye, the catalyst was used both in calcination at 300 ℃ and without calcination. Parameters such as the amount of catalyst, the concentration of dye, the pH of dye sol, and the temperature were calculated. Pseudo first order reactions according to Langmuir-Hinshelwood kinetics could be obtained from the result of photocatalytic reactions. Parameters such as energy activation (Ea), enthalpy of activation (ΔH⁰), entropy of activation (ΔS⁰) and free energy of activation (ΔG⁰) were calculated. The activation energy was equal to 11.719 ± 1 and 11.083 ± 1 kJ/mol for MG dye in the presence of Cu₂O nanoparticles in both two cases of calcination and without calcination respectively.

The antibacterial activity of various nanoparticles is gaining increasing interest due to its potential medical applications. In this work, we presented the synthesis of copper oxide nanoparticles prepared by chemical reduction from aqueous solutions of copper sulfate (CuSO₄) with sodium borohydride (NaBH₄) and hydrazine hydrate (N₂H₄) as reductant and polyvinylpyrrolidone (PVP) as stabilizer. The X-ray diffraction spectra showed the formation of tenorite (CuO) and cuprite (Cu₂O) nanoparticles when different ratios of CuSO₄/NaBH₄ and CuSO₄/N₂H₄ were used. Photographs obtained by transmission electron microscopy (TEM) showed agglomerates of grains with a narrow size distribution (from 20 to 70 nm), whereas the radii of the individual particles were between 2 and 20 nm. Smaller nanoparticles and narrower particle size distributions were obtained when NaBH₄ was used. The results of antibacterial activity using the Kirby-Bauer method showed that nanoparticles obtained with NaBH₄ presented a reasonable bactericidal activity. Pseudomonas aureginosa and Staphylococcus aureus were more susceptible to the particle size than Escherichia coli. In addition, with small amounts of Cu₂O in samples of CuO nanoparticles, the antibacterial susceptibility against Pseudomonas aureginosa was improved. Finally, nanoparticles of CuO incorporated into cotton by applying ultrasound waves remained impregnated after five washes.