Oxide-graphene hybrid powders for solar thermal evaporation of saline water, Nadhira Laidani, Francesca Marchetti, Hafeez Ullah, Gloria Gottardi, Ruben Bartali, Marina Scarpa, Said Makhlouf, Ilyes Mitiche and Omar Lamrous

Access to clean water, suitable for human consumption and domestic uses, is increasingly becoming the most important issue facing people around the world. For countries with plenty of solar light and scarce water, direct solar energy use for desalination is the most appropriate for a large exploitation by non-industrial communities. Nanomaterials, graphene in particular, are increasingly gaining interest in this field, thanks to their peculiar electronic, thermal and optical properties. In this work, graphene and oxide/graphene hybrids suspensions in water were tested for their ability to increase the light-to-heat conversion and water evaporation efficiency. The hybrid materials were developed by means of radio-frequency sputtering of oxides (Nb2O5 and SiO2) onto graphene powder. A substantially positive effect of graphene on saline water evaporation rate measured under a 1 sun solar simulator was observed, while the presence of the oxides was found to improve the graphene dispersion in water. The samples were characterized by means of X-ray photoelectron and Raman spectroscopies. UV-Vis spectrophotometry and contact angle measurements were employed to characterize the treated powder suspension stability in water.