Carbon quantum dots in synergistic conjugation with polypyrrole: A sustainable binder-free electrode for ultracapacitor applications

Herein, binder-free supercapacitor electrodes based on Polypyrrole (PPy), carbon quantum dots (CQDs), and Polypyrrole/carbon quantum dots (PPy/CQDs) with varying percentages of CQDs were designed using in-situ oxidative polymerization. Out of all the electrodes fabricated, PPy-CQD3 supercapacitor device studied in its binder-free form, exhibited outstanding supercapacitor properties compared to other fabricated devices. Specifically, PPy-CQD3 demonstrated the highest specific capacitance of 2985 F/g at 10 mV/s. The PPy-CQD3 device also showed a high energy density of 467 Wh/kg, a power density of 2594 W/kg, and a capacitance retention of 96 % of its initial specific capacitance after 5000 cycles at a given current density. The resultant composite demonstrated high specific capacitance, reaching 2838 F/g in 0.1 M H 2 SO 4 at a current density of 1.8 A/g without binder. This remarkable performance is attributed to the combined effects of PPy, CQDs, and the porous morphology of the PPy-CQDs composite. The binder-free supercapacitor electrode with its exceptional electrochemical performance shows great potential in applications such as wearable electronics, touch screens, electronic paper, and roll-up displays.