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Graphene oxide/Cuprous oxide (GO/Cu2O) composite is a visible light photocatalyst for the degradation of dyes. A simple and efficient approach for preparing GO/Cu2O composite adopted in this study involves reducing cuprous oxide precursors in the presence of graphene oxide using an aqueous solution of pulp derived from banana fruit. The GO/Cu2O composite was characterized by Fourier transform infrared spectroscopy (FT-IR), Diffused reflectance Ultraviolet visible spectroscopy (DRS UV-Vis), Raman spectroscopy and Field Emission Scanning electron microscopy (FE-SEM). Cu2O particles were distributed randomly on the graphene oxide sheets due to the template effect of GO. The results showed higher photocatalytic activity for the composite (band gap 2.13 eV), for the degradation of the organic dyes (Methylene blue and Rhodamine-B). The enhanced photocatalytic activity is due to effective charge transfer from GO to Cu2O, and high specific surface area which improves the effective separation of the generated electron–hole pairs. Our present study is inspired by a facile, low cost, green production of (GO/Cu2O) composite whose photocatalytic activity can be extended to degradation of all other water-born textile dyes.

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NiWO4 nanostructures doped with different ratios of Eu 3+ have been prepared by a chemical precipitation method. The influence of Eu 3+ on NiWO4 nanostructures were characterized using X-ray diffraction (XRD), UV-visible diffuse reflectance spectra, scanning electron microscopy (SEM) and Raman. XRD patterns display that the samples crystallize to monoclinic wolframite structure. SEM images reveal that the particles are well uniformly dispersed with average particle size lies around 40-50nm. Third-order nonlinear optical properties were studied by a Z-scan technique at 532 nm using continuous wave diode pumped Nd:YAG laser. Open and closed aperture results reveal the nanostructures to possess reverse saturation absorption and negative nonlinear refraction. The calculated absorption coefficients (β), imaginary part of third-order susceptibilities Imχ (3) are in the order of 10 -6 (cm/W) and 10 -7 esu. These results indicated that the synthesized nanostructures could be promising materials for optical device applications.