Synthesis of multifarious hierarchical flower-like NiO and their gas-sensing properties

Monodisperse NiO with hierarchical nanostructures has been successfully synthesized via a surfactant-assisted hydrothermal process followed by subsequent calcination treatment. It is notable that the NiO nanoflowers are self-assembled by abundant ultrathin nanosheets, and polyvinylpyrrolidone (PVP) plays a key role on the constructions of flower-like architectures. In addition, gas sensors based on NiO nanoflowers were developed and demonstrated outstanding functionalities, owing to the open and well-defined structure as well as abundant micro reaction rooms built by nanosheets. Moreover, a feasible formation mechanism was put forward in detail to illuminate the morphology evolution and the interactions between PVP and Ni 2+ ions.