Ultrasound-assisted bottom-up synthesis of Ni-graphene hybrid composites and their excellent rhodamine B removal properties

In this paper, a facile one-pot bottom-up approach has been developed for the rapid preparation (<= 5 min) of graphene nanostructures and Ni-graphene hybrid composites. Under the aid of ultrasonic irradiation, the graphene nanostructures were prepared via reducing hexachloro-benzene(C6Cl6) with sodium (Na) in non-polar organic solvent n-tetradecane (C14H30). On the basis of this route, the Ni-graphene hybrid composites were easily synthesized by adding Ni nanoparticles (NPs) into reaction system. The whole reaction was carried out at low temperature (100-120 degrees C) and in air atmosphere. Despite the absence of nitrogen protection, the result from surface analysis still shows a relatively high C/O ratio (10:1). The effect of the Ni NPs content and size on the specific surface area (SSA) of the products is also investigated. The synthesized samples exhibit large SSA, which is significantly affected by the Ni NPs content rather than their size. The adsorption performances of the samples are evaluated for the removal of organic dyes such as rhodamine B (RhB) from aqueous solutions. The testing results show great adsorption capacity (q(max) = 963.04 mg g(-1)), rapid adsorption rate (similar to 99.88%, 2 min), high adsorption efficiency (>99.7%) and good chemical stability in a wide pH range (3-13), high salt tolerance (>80 mg mL(-1)), and good recyclability (>99.5%, 20 cycles).