Nanoporous cobalt foam and a Co/Co(OH)2 core–shell structure for electrochemical applications

Abstract

Nanoporous metal foams have good electrical and thermal conductivities and potential catalytic activities because of their high surface areas. In this study, nanoporous cobalt foam was prepared by simple consolidation of a pearl-necklace-type CNT/Co₃O₄ nanocomposite powder. During heat treatment of the pre-compacted powder in an inert atmosphere, Co₃O₄ particles were reduced to cobalt metal and formed a three-dimensional, continuous nanoporous metallic structure. This nanoporous cobalt foam could be used as an excellent conducting framework because of the superior electrical conductivity of the metal. A Co/Co(OH)₂ core–shell structure was prepared by coating Co(OH)₂ onto the nanoporous cobalt foam and using it as the electrode for a supercapacitor. Because of the high surface area of the nanoporous cobalt metal frame, the Co/Co(OH)₂ core–shell structure had a specific capacitance of 525 F g⁻¹ at a current density of 0.5 A g⁻¹.