Reduced graphene oxide nanosheets doped by Cu with highly efficient visible light photocatalytic behavior

Graphene oxide (GO) and reduced graphene oxide (RGO) exhibit good electrochemical properties due to their semiconducting nature, large surface area, high concentration of functional groups and unique layered structure. They have been used widely for the removal of heavy metal ions, dyes and other organic contaminants from water. In the present study, a modified Hummer's method was used to prepare GO while Cu-doped RGO which was obtained by employing a simple hydrothermal process. X-ray diffraction analysis confirmed the presence of GO sheets and Cu-doped RGO in the synthesized product. Examination with field emission scanning and high resolution transmission electron microscopes revealed an ultrathin, porous and layered structure of GO nanosheets while RGO sheets appeared as a well-defined, layered and non-agglomerated sponge. Dispersion of Cu within RGO sheets was also confirmed during microstructural study. Optical properties, such as absorption of light and bandgap width, were studied using UV–visible spectroscopy. Photoluminescence characterization showed maximum emission between 300 and 350 nm (UV region) caused by the presence of vacancies and surface defects in synthesized sheets. In aqueous media, methylene blue (MB) pollutant was photodegraded up to 91% within 80 min when Cu-doped RGO photocatalyst was employed under visible light irradiation. The present work shows the ability of Cu-doped RGO to degrade aqueous pollutants in an efficient manner. In conclusion, this product can find potential application in the removal of organic pollutants from wastewater.