Controlled synthesis of hierarchical NiO nanosheet hollow spheres with enhanced supercapacitive performance

Abstract

In this work, we report a facile strategy for the controlled synthesis of nickel oxide (NiO) hollow spheres (HSs) assembled from nanosheets (NSs). The Ni₂CO₃(OH)₂ NSs are first grown on sulfonated polystyrene (sPS) hollow spheres by a low-temperature solution route. NiO HSs with well preserved morphology are then obtained by calcining the as-prepared sPS@ Ni₂CO₃(OH)₂ NSs composite HSs. Because of the hollow interior and hierarchical structure, these NiO nanosheet hollow spheres have a relatively high specific surface area of 62 m² g⁻¹. When evaluated for supercapacitive performance, these hierarchical NiO HSs demonstrate improved electrochemical properties with a high capacitance of 415 F g⁻¹ even at a high charge–discharge current rate of 3 A g⁻¹ and 91% of which can be retained after 1000 charge–discharge cycles.