Abstract
The current paper describes enhanced electrochemical capacitive performance of chemically grown Cobalt hydroxide (Co(OH)2) nanorods (NRs) decorated porous three dimensional graphitic carbon foam (Co(OH)2/3D GCF) as a supercapacitor electrode. Freestanding 3D porous GCF is prepared by carbonizing, high internal phase emulsion (HIPE) polymerized styrene and divinylbenzene. The PolyHIPE was sulfonated and carbonized at temperature up to 850 °C to obtain graphitic 3D carbon foam with high surface area (389 m2 g−1) having open voids (14 μm) interconnected by windows (4 μm) in monolithic form. Moreover, entangled Co(OH)2 NRs are anchored on 3D GCF electrodes by using a facile chemical bath deposition (CBD) method. The wide porous structure with high specific surface area (520 m2 g−1) access offered by the interconnected 3D GCF along with Co(OH)2 NRs morphology, displays ultrahigh specific capacitance, specific energy and power. The Co(OH)2/3D GCF electrode exhibits maximum specific capacitance about ~1235 F g−1 at ~1 A g−1 charge-discharge current density, in 1 M aqueous KOH solution. These results endorse potential applicability of Co(OH)2/3D GCF electrode in supercapacitors and signifies that, the porous GCF is a proficient 3D freestanding framework for loading pseudocapacitive nanostructured materials.
Highlights
Cobalt hydroxide (Co(OH)2) nanorods (NRs) decorated porous three dimensional graphitic carbon foam (Co(OH)2/3D graphitic carbon foams (GCFs)) as a supercapacitor electrode
PolyHIPE was synthesized by copolymerizing styrene and divinyl benzene on the water-in-oil high internal phase emulsion (HIPE) template stabilized by span 80 and to account fabrication of GCF, the schematic is shown in Fig. 1 (and reaction scheme given in Figure S1 (See ESI))
Sulfonation of polyHIPE with concentrated sulfuric acid is much more effective to create strongly interacting sulfonate moieties in order to stabilize the polymer through initial stages of carbonization and activates surface of polyHIPE to generate mesopores and micropores on walls of 3D carbon foam[32]
Summary
Nanorods Based High Performance received: 24 May 2016 accepted: 19 September 2016. Umakant M. These obvious intensities of D and G band with ratio up to 1 attributed to partial graphitic structure of prepared carbon foam[41]. The graph reveals that, specific capacitance decreases with increase in GCD current densities This result indicating that, at higher charging rates, a surface confined redox process may occur, which specifies the limitation arising from the charge transfer kinetics[47]. For an ideal double-layer capacitor, the impedance plot should be a vertical line, parallel to imaginary axis and notably GCF electrode shows almost parallel line to imaginary impedance (shown in inset of Fig. 5(c)), which is generally observed for carbon-based materials such as activated carbon, graphite, CNTs, and graphene[49]. The obtained maximum specific capacitance is higher than that reported for Co(OH)[2] with various nanostructures on different substrate and graphene-Co(OH)[2] composites[17,40,53,54,55,56,57,58], as shown in Fig. 6(b), with the exception of chlorine doped Co(OH)[2] (9894 F g−1) on the Ni foam electrode[52]
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