(541a) Synthesis of Hollow Co3O4 Nanoparticles on Nitrogen–Doped Porous Carbons for High-Performance Supercapacitors

Supercapacitors have been considered as next generation energy storage devices due to their high power density caused by rapid charge/discharge rates, long life cycle and eco-friendliness. In view of electrode materials, several strategies to improve performance of the supercapacitors were suggested and applied. We incorporated Co₃O₄ nanoparticles into nitrogen-doped porous carbons to investigate their potential as supercapacitors. The nano-sized Co₃O₄ particles grow and their morphology becomes hollow on the carbon support, which is attributed to the atomic diffusion (the Kirkendall effect) during the annealing. The cobalt-doped composites have high BET surface areas of about 3000 m² g^-1 and possess mesopore-dominant structures caused by the hollow Co₃O₄ nanoparticles. As a result, the hollow Co₃O₄ in the composites simultaneously induces both enhanced pseudo-capacitance and efficient pore structure for energy storage. The specific capacitance of the composites is as high as 300 F g^-1 in an aqueous solution of 6 M KOH at 1 A g^-1, and the material shows competitive specific capacitance of 210 F g^-1 at 10 A g^-1 for a high power density. The present study provides a unique insight into the synthesis of hollow nanoparticles on a porous substrate material for high-performance supercapacitance.