Rational synthesis of hierarchically porous NiO hollow spheres and their supercapacitor application

Abstract Hierarchically porous-structured hollow spheres with the shell composed of nanosized building blocks are of great importance to the next-generation of electrochemical devices. We present a powerful chemical bath deposition method for the fabrication of hierarchically porous NiO hollow spheres composed of nanoflakes with thicknesses of ∼10 nm. A plausible mechanism is proposed to explain the formation of the NiO hollow spheres. Supercapacitor electrodes based on the NiO hollow spheres are characterized. The NiO hollow spheres exhibit a specific capacitance of 346 F g −1 at 1 A g −1 after 2000 cycles and an excellent cycling stability, owing to the unique hollow-sphere architecture providing fast ion/electron transfer. Our growth approach may offer a new strategy for the synthesis of other transition metal oxides hollow spheres for applications in electrochemical energy storage, catalysis, and gas sensing.