Impact of separator on the electrochemical performance of g-C3N4/Co3O4 nanohybrid symmetric supercapacitors
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Date
2026
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Abstract
The present study aims to evaluate the influence of different separators on the electrochemical performance of a
2D g-C3N4 decorated Co3O4 symmetric supercapacitor. Exfoliated graphitic carbon nitride (ECN) was combined
with Co3O4 to create nanocomposites in weight ratios of 1:0.01, 1:0.05, and 1:0.1 (COCN1, COCN2, COCN3).
XRD analysis revealed that the ECN possesses a hexagonal structure, while Co3O4 exhibits a cubic spinel
structure. COCN nanocomposites have been successfully synthesized, as confirmed by analyses using XRD and
FTIR techniques. HR-TEM and SAED indicated that the CO3O4 adhered to the g-C3N4 matrix. The BET analysis
revealed that the ECN and COCN2 show specific surface areas of 25 m2/g and 35 m2/g, respectively. The COCN2
nanocomposites attain a specific capacitance of 667.8 F/g at 1 A/g in 1.0 M KOH electrolyte, which is eight times
more than ECN, due to the combined effects of the nitrogen content and cobalt oxidation states. The COCN2
exhibits an energy density of 45.45 Wh/kg at 218.75 W/kg power density, with 99.5 % capacitive retention. To
explore the influence of different separators in symmetric devices, COCN2 was employed within the Swagelok
assembly, featuring two separate types of separators: Whatman paper (COCN2/W/COCN2) and PVA-KOH gel
electrolyte (COCN2/GE/COCN2). The COCN2/W/COCN2 device achieved a specific capacitance of 197.25 F/g at
a current density of 1.0 A/g. Furthermore, it attained an energy density of 140.27 Wh/kg at a power density of
1600 W/kg, while retaining 94.23 % of its initial capacitance. In contrast, the COCN2/GE/COCN2 device showed
a specific capacitance of 69.25 F/g and an energy density of 24.62 Wh/kg at 1600 W/kg, maintaining 95.4 % of
its capacitance after 1000 cycles. The synergistic combination of Co3O4 and g-C3N4 offers a promising strategy
for enhancing energy.