A binder-free porous graphene/functionalized multiwalled carbon nanotubes composite containing nickel hydroxide as a supercapacitor electrode

In this paper, porous graphene (PG)/functionalized multiwalled carbon nanotubes (f-MWNTs) composite was first synthesized through a catalytic chemical vapor deposition (CCVD) followed by hydrothermal procedure. The prepared f-MWNTs/PG composite was then embedded into Ni foam (NF) via direct electrophoretic deposition, and Ni(OH)₂ nanoplates were simultaneously deposited on the surfaces of both porous graphene and f-MWNTs through a simple electrochemical deposition. The obtained Ni(OH)₂@f-MWNTs-PG deposit was characterized through XRD, FT-IR, Raman, DSC-TGA, BET, FE-SEM, and TEM techniques. These analyses results verified that β-Ni(OH)₂ nanoplates uniformly anchored onto both components of the electrodeposited composite. The charge storage ability of the fabricated Ni(OH)₂@f-MWNTs-NPG/NF was tested as a binder-free supercapacitor electrode through cyclic voltammetry, continuous charge–discharge cycling, and AC impedance techniques, and compared with pristine Ni(OH)₂/Ni foam electrode. The specific capacities as high as 374.5 mAh g^− 1 and 277 mAh g^− 1 at the current loads of 0.5 and 10 A g^–1 were respectively achieved for the prepared composite/NF electrode. Also, the cycling abilities of 94.8% and 77.8% were obtained after 5000 continuous charge–discharge cycles at 2 and 6 A g^–1, respectively. The outstanding capacitive capability of the fabricated composite electrode was assigned to the synergetic contributions between the Ni(OH)₂ nanoplates and porous graphene/functionalized MWNTs and their rational architecture in the composite matrix.