  NiCo2O4 of varying nanostrucutures ranging from nanowires, nanoplates to
nano-plates@nanowires were successfully grown on microporous (MP) Ni foams via
one-step hydrothermal process. The investigation of electrochemical capacitance
favors Ni-Co2O4 of nanoplates@nanowires microstructures which possesses
specific capacitance of 1380.3 F/g and 1033F/g at 5A/g and 50A/g respectively
and 86.7% capacitance re-tention after 5000 cycles at 30A/g. The relationship
between morphology and specific capacitance was further explored by the model
of surface roughness factor (RF), which is indicative of the active
electrode-electrolyte interface areas. The RF of porous Ni@NiCo2O4 was
remarkably improved by employing hierarchically porous (HP) Ni monoliths as
substrates, which illustrates the model of high energy density (12.6 F/cm2)
electrodes for super-capacitors.
