Pseudocapacitive properties of cobalt hydroxide electrodeposited on Ni-foam-supported carbon nanomaterial

• Co(OH)2/graphene and Co(OH)2/amorphous carbon were prepared.
• Co(OH)2/graphene reveals a high cycling stability even at a high current density.
• Co(OH)2/amorphous carbon exhibits a high specific capacitance.
• Influence of carbon on pseudocapacitive behaviors of Co(OH)2 has been studied.

Cobalt hydroxide has been cathodically deposited in Co(NO3)2 aqueous solution on nickel-foam-supported carbon nanomaterial, including vertically oriented graphene nanosheets (GNS) or amorphous carbon (APC). The results indicate that the GNS has a slightly different effect on the morphology of α-Co(OH)2 from the APC. Although the cycling stability either for Co(OH)2/GNS or Co(OH)2/APC is higher than that of Co(OH)2/Ni foam, Co(OH)2/GNS exhibits a higher value (95.7% of initial capacitance can be maintained after 2000 charge-discharge cycles at high current density of 40 Ag−1) compared to Co(OH)2/APC (83.8% remains). However, Co(OH)2/APC has a higher specific capacitance (1287.2 F g−1 at 2 Ag−1) than Co(OH)2/GNS (692.0 F g−1). The effect of carbon nanomaterials on the capacitive characteristics for the Co(OH)2 has been explored.

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