Inquiring the photocatalytic activity of cuprous oxide nanoparticles synthesized by a green route on methylene blue dye

We synthesized cuprous oxide (Cu2O) nanoparticles (NPs) with an average crystallite size of 8.8 nm in presence of Arka (Calotropis gigantea) leaves extract. The photo-bleaching activity of Cu2O NPs on the aqueous methylene blue (MB) dye was studied by illumination of visible light. In the absorption spectra, a decrease in the absorption peak intensity at 665 nm of MB was observed in presence of Cu2O NPs. A red shift in its peak position as a function of irradiation time is suggesting that oxide particles are degrading the organic dye in an aqueous medium. In the vibration spectra, red shift in the C-H stretching band (2954, 2926, and 2855 cm(-1)) of methylene group and C-N stretching band (1343 and 1226 cm(-1)) of MB in presence of Cu2O NPs proposes a surface adsorption of MB over NP's surfaces. Quenching in the emission band intensity and red shifts in the peak maxima of MB in presence of Cu2O NPs is ascribed to the charge transfer interaction between MB and oxide NPs. A linear Stern-Volmer plot reveals that decrease in the emission intensity of MB dye occurs via the dynamic quenching mechanism. Synthesis of Cu2O NPs of various architectures using a green route could be use as an approach towards the cost-effective treatment of water pollutants.