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

Abstract Cobalt hydroxide has been cathodically deposited in Co(NO 3 ) 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.