Facile synthesis of hierarchically structured NiO flower-like hollow spheres

The hierarchical flower-like NiO hollow spheres were synthesised by a facile method without using any templates or surfactants. The as-prepared sample and precursor were characterised by X-ray diffraction and field emission scanning electron microscopy. The results indicated that the as-prepared NiO is self-assembled hierarchically. During the assembly of NiO, the reaction time plays an important role. The flower-like NiO hollow sphere showed much higher catalytic activity than large-size NiO or hollow NiO for the oxidative dehydrogenation of ethane to ethylene due to its special structure.