Formation of Hollow Co3O4 Nanoparticles on Nitrogen-doped Porous Carbons for Highly Capacitive Performance

Abstract

Co3O4 nanoparticles are incorporated 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.