Fig 1.
(A) XRD patterns of the products prepared using different electrodeposition modes. (B) EDX of the CY7 electrode.
Fig 2.
FESEM (left) and TEM (right) images of (A) CP, (B) CA, and (C) CY7 electrodes.
Fig 3.
FESEM images of (A) CY4, (B) CY7, (C) CY10, and (D) CY13 and (E) TEM images of CY4 (inset: lattice spacing).
Fig 4.
CV profiles of as-prepared electrodes obtained using different electrodeposition modes.
Fig 5.
(A) CV curves at a scan rate of 5 mVs−1, (B) CD curve at a current density of 1 Ag−1 in a voltage range of −0.6 V to 1 V, and (C) specific capacitance determined from the discharge graph of the deposited mass versus the number of deposition cycles.
Fig 6.
(A) Nyquist plot of all electrodes in the frequency range from 10 mHz to 100 kHz in Na2SO4 electrolyte, (B) Bode plots of the frequency’s dependence on the impedance magnitude (|Z|), (C) Bode plots of the frequency’s dependence on the phase angle (ϕ), and (D) specific capacitance retention until the 1000th cycle.
Table 1.
Equivalent circuit parameters deduced by fitting Nyquist plots and the frequencies at ɸ = −45° for all electrodes.
Fig 7.
CV curves of CY4 at a scan rate of 5 mVs−1 within the potential range of −0.5 V to 0.5 V in (A) 0.5-M Na2SO4, (B) 0.5-M KOH, (C) mixed 0.5-M KOH/0.04-M K3Fe(CN)6, and (D) 0.04-M K3Fe(CN)6.
Fig 8.
Schematic of the role of hexacyanoferrate (II) and (III) in the processes of (A) charge and (B) discharge in the CY4 electrode.
Fig 9.
(A) CD profiles of the CY4 electrode’s current density at 20 Ag−1 in three different electrolytes, (B) CD profiles collected using different applied current densities in mixed KOH/K3Fe(CN)6, and (C) specific capacitance retention after the 1500th cycle at a scan rate of 10 mVs−1 in the potential range from −0.5 V to 0.5 V.