Hydrothermal synthesis of hierarchical mesoporous NiO nanourchins and their supercapacitor application

•Urchin-like NiO hierarchical architectures have been successfully prepared.•The NiO nanourchins exhibited high specific capacitance value (540.5 F g−1).•Discuss the reasons for the excellent performance of NiO nanourchins.

An urchin-like porous NiO electrode material was synthesized via a simple hydrothermal method. The urchin-like NiO architectures are constructed by numerous nanorods which are assembled by irregular nanoparticles with a diameter ranging from 5 to 10 nm. Electrode materials based on the mesoporous NiO nanourchins exhibited high specific capacitance value (540.5 F g−1) at a current density (1 A g−1), as well as good cycling stability. This excellent performance may be attributed to following factors: (1) a large specific surface area and more active sites provided by the unique hierarchical architectures; (2) effective contaction and diffusion between the electrode and electrolyte owing to the porous urchin-like structure; (3) the interconnected interspaces among the nanoparticles, which serve as an “ion reservoirs” to shorten ion diffusion length.