Porous cobalt chalcogenide nanostructures as high performance pseudo-capacitor electrodes

Abstract

Electrochemical supercapacitor is an essential technology that is pivotal for the development of reliable energy storage devices. Herein, we report the fabrication of supercapacitor electrodes using nanostructured porous cobalt chalcogenide (CoTe<inf>2</inf> and CoSe<inf>2</inf>) electrodes, anticipating an enhanced performance owing to their higher contact area with electrolyte and large pore volume enabling shorter diffusion paths for ion exchange. In this regard, we synthesized CoTe<inf>2</inf> and CoSe<inf>2</inf> nanostructures via an anion-exchange-reaction between pre-synthesized Co(OH)<inf>2</inf> hexagonal nanosheets and chalcogen (tellurium and selenium) ions under hydrothermal conditions. Structural, morphological and compositional properties of the as-synthesized materials are examined using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. Pseudo-capacitive properties of CoTe<inf>2</inf> and CoSe<inf>2</inf> nanostructures as working electrodes are studied through cyclic voltammetry and galvanostatic charge-discharge methods using an electrochemical workstation. CoSe<inf>2</inf> electrode delivered a specific capacitance of 951 F g?1 at a scan rate of 5 mV s?1, which surprisingly is almost three times higher in comparison to CoTe<inf>2</inf> electrode (360 F g?1). Both CoTe<inf>2</inf> and CoSe<inf>2</inf> electrodes exhibited good capacitance retention capability for 2500 CV cycles. The superior electrochemical performance of the nanoporous CoSe<inf>2</inf> electrode indicate their applicability for high-performance energy storage device applications. © 2017 Elsevier Ltd