Synthesis and characterization of aerogel-like mesoporous nickel oxide for electrochemical supercapacitors

Highly porous NiO was prepared via a combination of sol-gel process with supercritical drying method in this paper. The as-synthesized NiO samples exhibit 80–90% porosity and high surface area, ie, 180.5–325.6 m2g−1. Cyclic voltammetric and chronopotentiometric measurements indicated the aerogel-like NiO in 1 mol.L−1 KOH solution to behave capacitive well due to its uniform mesoporous microstructure. It was also observed that post-heating temperature plays a critical role in the mesoporous nature of the aerogel-like materials. An optimal heating temperature of 300∘C was found to favor the formation of mesopores, which account for the large specific capacitance of as high as 125 F.g−1. The average specific capacitance of the aerogel-like NiO was observed to be about 75–125 F.g−1 between a potential window of 0–0.35 V vs. SCE.