Investigations on Electrochemical Activity of Polycarbazole/Cadmium Sulfide/Hematite Iron (III) Oxide (PCz/CdS/α-Fe2O3) Nanocomposite Electrode for Supercapacitors

Abstract

A novel ternary polycarbazole/cadmium sulfide/hematite iron (III) oxide (PCz/CdS/α-Fe₂O₃) nanocomposite was synthesized through in situ chemical polymerization method. The phase structure and morphology of PCz, PCz/CdS, PCz/α-Fe₂O₃, and PCz/CdS/α-Fe₂O₃ were analyzed using XRD and FESEM techniques. From HR-TEM study, particle size of PCz/CdS/α-Fe₂O₃ nanocomposite was found to be 68.09 nm. The chemical composition and the binding energy of the elements present in PCz/CdS/α-Fe₂O₃ nanocomposite were examined through XPS. BET studies revealed the mesoporous nature of PCz/CdS/α-Fe₂O₃ with a large surface area (35.51 m² g⁻¹) compared to PCz/α-Fe₂O₃ (21.52 m² g⁻¹) and PCz/CdS (7.47 m² g⁻¹) nanocomposites. Cyclic voltammetric studies revealed the highest specific capacitance (634.14 Fg⁻¹) of ternary PCz/CdS/α-Fe₂O₃ electrode in KOH electrolyte in comparison to H₂SO₄ (49.44 Fg⁻¹) and Na₂SO₄ (79.94 Fg⁻¹) electrolytes at a scan rate of 3 mVs⁻¹. Cyclic stability test indicated a high capacitive retentivity of PCz/CdS/α-Fe₂O₃ (97%) electrode than PCz/CdS (90%) and PCz/α-Fe₂O₃ (93%) electrodes after completion of 2000 cycles. From EIS, PCz/CdS/α-Fe₂O₃ displayed a low ESR value (1.35 Ω) than the binary electrodes; the value increased slightly after the cyclic stability analysis. All these indicate the effectiveness of PCz/CdS/α-Fe₂O₃ as a suitable electrode for supercapacitors.