Biofabrication of highly pure copper oxide nanoparticles using wheat seed extract and their catalytic activity: A mechanistic approach

A facile novel green methodology is presented for the synthesis of highly stable and well-dispersed copper oxide nanoparticles using aqueous wheat seed extract. Under optimal reaction conditions, the wheat seed extract-derived electron-rich biomolecules were functioned as a reducing and capping/stabilizing agent. The ultraviolet-visible absorption peak at 300 nm was confirmed the formation of copper oxide nanoparticles. Fourier-transform infrared spectroscopy analysis determined Cu-O bonds in nanosample, indicating the active role of functional groups in the wheat seed extract in bio-reduction of Cu cations. X-ray diffraction pattern results demonstrated the monoclinic structure of highly pure bio-synthesized copper oxide nanoparticles with a crystallite size of 20.76 nm. The stability of copper oxide nanoparticles was confirmed after 3 months' storage of product with no sedimentation or suspension. Transmission electron microscopy results showed the spherical shape of nanoparticle with an average size of 22 +/- 1.5 nm. X-ray photoelectron spectroscopy analyses revealed only copper and oxygen elements in the sample, confirming the purity of copper oxide nanoparticles. Bio-assisted copper oxide nanoparticles demonstrated significant catalytic efficiency and reusability toward 4-nitrophenol removal by an average of 97.6% from aqueous solutions after successive 5 days' exposure to UV irradiation.