Fabrication of porous β-Co(OH)₂ architecture at room temperature: a high performance supercapacitor

Abstract

A facile, cost-effective, surfactant-free chemical route has been demonstrated for the fabrication of porous β-Co(OH)₂ hierarchical nanostructure in gram level simply by adopting cobalt acetate as a precursor salt and ethanolamine as a hydrolyzing agent at room temperature. A couple of different morphologies of β-Co(OH)₂ have been distinctly identified by varying the mole ratio of the precursor and hydrolyzing agent. The cyclic voltammetry measurements on β-Co(OH)₂ displayed significantly high capacitance. The specific capacitance obtained from charge–discharge measurements made at a discharge current of 1 A/g is 416 F/g for the Co(OH)₂ sample obtained at room temperature. The charge–discharge stability measurements indicate retention of specific capacitance about 93% after 500 continuous charge–discharge cycles at a current density of 1 A g^–1. The capacitive behavior of the other synthesized morphology was also accounted. The nanoflower-shaped porous β-Co(OH)₂ with a characteristic three-dimensional architecture accompanied highest pore volume which made it promising electrode material for supercapacitor application. The porous nanostructures accompanied by high surface area facilitates the contact and transport of electrolyte, providing longer electron pathways and therefore giving rise to highest capacitance in nanoflower morphology. From a broad view, this study reveals a low-temperature synthetic route of β-Co(OH)₂ of various morphologies, qualifying it as supercapacitor electrode material.