Hierarchical nanostructures of nickel-doped zinc oxide: Morphology controlled synthesis and enhanced visible-light photocatalytic activity

Nickel-doped zinc oxide hollow nanospheres have been synthesized using a simple solvothermal approach through a morphological transformation driven by a localized Ostwald ripening process. The saturation magnetization of the system shows that the materials have only a short-range magnetic ordering in them. Based on the visible-light photocatalytic experiment, we could confirm that, with a high doping content (10 mol%), the doping accompanied with increased recombination which reduced the energy of photoinduced electron leading to suppressed photocatalytic activity. Changing reaction parameters, i.e. the mixed reactant concentration, doping content, and different solvents, Zn1−xNixO powders exhibited the elongated prismatic form with sharp tips, quasi-spherical structure, and hexagonal-based polyhedron, respectively. The photocatalytic results demonstrate that different crystal growth orientations, specific surface areas, particle size distributions, and doping levels have strong influences on the photocatalytic activity performances. Among the samples, hexagonal-based polyhedrons have the best photodegradation efficiency standing on higher fraction of exposed polar facets, larger specific surface area, as well as an optimal doping level. The 1 mol% nickel content showed the best photocatalytic activities among the nickel-doped zinc oxide samples.