Optical and electrochemical analysis of nitrogen-doped carbon quantum dots from Moosa balbeesiaana peels for advanced supercapacitor applications

The demand for suitable electrode materials for energy storage devices, driven by increasing energy needs and environmental concerns, has led to the investigation of green synthesis methods. In this study, a composite material (rGO@NCQDs) comprising nitrogen-doped carbon quantum dots (NCQDs) derived from Moosa balbeesiaana peels and reduced graphene oxide (rGO) was synthesized via hydrothermal methods to evaluate its photophysical properties and electrochemical performance for supercapacitors applications. Additionally, the electrochemical behavior of rGO NCQDs combined with Vanadium pentoxide (V 2 O 5 ) was explored. Characterization techniques including FTIR spectroscopy revealed typical carbon-based material features in rGO-decorated NCQDs, and rGO NCQDs@V 2 O 5 composite. SEM analysis illustrated distinctive surface structures (mushroom-shaped for rGO@NCQDs and flowered-shaped for rGO NCQDs@V2O5), while XRD confirmed crystalline structures with specific sizes. Photophysical investigations demonstrated significant Solvatochromic shifts and strong solute-solvent interactions in the composites. Electrochemical studies, including cyclic Voltammetry and Galvanostatic measurements, exhibited promising performance metrics. Specifically, rGO@NCQDs demonstrated a specific capacitance of 134.68 Fg −1 with excellent retention over 5000 charge-discharge cycles. In contrast, rGO NCQDs@V 2 O 5 exhibited a maximum specific capacitance of 562.62 Fg −1 at a scan rate of 10 mVs −1 and exceptional cycle stability (96 % retention over 5000 cycles). These findings highlight the potential of the synthesized composites as efficient electrode materials for supercapacitors, offering enhanced electrochemical performance and stability. The study underscores the importance of green synthesis approaches in developing functional materials for sustainable energy storage applications.