Kinetically controlled selective synthesis of Cu₂O and CuO nanoparticles toward enhanced degradation of methylene blue using ultraviolet and sun light

Two different stable forms of copper oxide (Cu₂O and CuO) nanoparticles (NPs) were selectively synthesized through a smart approach using the same precursor but different reagent amounts. The fabrication strategy is cost-effective and relatively easy. The bandgap energies of the as-synthesized Cu₂O- and CuO-NPs, as determined from Tauc plots, are 2.08 and 1.82 eV, respectively. The photocatalytic performance of these NPs was assessed through their use in the photodegradation of an organic-dye water contaminant under UV and solar-light illumination. Methylene blue (MB) was chosen as a representative dye because of its ubiquitous presence in industrial wastewater and its hazardous effects on human health. The results of experiments involving the photodegradation of MB by the synthesized Cu₂O- and CuO-NPs revealed 97% and 81% photodecomposition efficiencies, respectively, during 60 min of UV-light illumination. When sunlight was used as a light source, and the duration was extended to 120 min, the photodecomposition efficiencies were 70% and 63% for the Cu₂O- and CuO-NP photocatalysts, respectively. The efficient degradation of MB solution by the as-prepared NPs implies that they are potentially potent photocatalysts for the treatment of wastewater originating from industrial and domestic sources.