Facile one-pot synthesis of highly monodisperse nickel microspheres with raised nickel dots and their adsorption performance for heavy metal ions.

This report describes the facile solvothermal synthesis of highly monodispersed nickel microspheres with surfaces uniformly covered by nickel dots. Synthesis parameters including reaction times and reagent concentrations significantly influence the microspheric particle characteristics. The novelty of the synthetic method in this work is twofold: first, the controlled synthesis of Ni metallic microspheres using ethylene glycol as the precursor of a reductant and urea as the origin of OH(-) has never been reported. Second, there are few studies on the construction of Ni microspheres covered by uniform Ni dots using a one-step solvothermal method. Importantly, the as-prepared Ni microspheres show an improved ability to remove Cd(2+) ions even at high concentrations in water and a unique adsorption isotherm having an increasing adsorption capacity for Cd(2+) ions. The presence of Ni dots was considered to play an important role in the onset of the adsorption process. We believe that this work opens up new and possibly exciting opportunities in the field of adsorption of heavy metal ions.