V. Balaji, R.R. Sasikaran, R. Yuvakkumar, Arjun Kumar Bojarajan, G. Ravi, Sambasivam Sangaraju
This study reports a sustainable and eco-friendly synthesis of uniformly dispersed, nano-spherical silver nanoparticles (Ag NPs) using Citrus sinensis ( C.s ) and Citrus limetta ( C.l ) peel extracts as natural bioreductants and stabilizing agents. The phytochemical constituents of the peels, enriched with flavonoids and polyphenols, effectively mediate the bio-reduction of Ag + ions and stabilize the resulting nanoparticles through strong interfacial interactions between surface-bound organic moieties and Ag NPs. These interactions facilitate enhanced electron mobility and redox kinetics, thereby improving charge storage capability and cycling durability. Structural and morphological analyses confirm the formation of crystalline, uniformly distributed Ag NPs. Electrochemical evaluation demonstrates remarkable specific capacitances of 523 F/g (Ag NPs( C.s )) and 608 F/g (Ag NPs( C.l )) at 0.25 A/g, with excellent retention of 89.91% and 95.96% after 5000 cycles, respectively. The assembled hybrid supercapacitors, Ag NPs( C.s )//AC and Ag NPs( C.l )//AC, exhibit outstanding cycling stability (89.09% and 93.18% capacitance retention) and high coulombic efficiency (~99.7%) even after 15,000 cycles, achieving high energy densities of 46 Wh/kg and 48 Wh/kg with corresponding power densities of 3789 W/kg and 3780 W/kg. This work establishes a green, waste-to-wealth route for the valorization of citrus peel waste into high-performance nanomaterials, offering significant potential for sustainable and scalable energy storage applications. • Green synthesis of Ag NPs using C. sinensis and C. limetta peel extracts. • FCC-structured Ag NPs confirmed by PXRD and TG–DSC analyses. • Specific capacitance: 523 F/g ( C.s ) and 608 F/g ( C.l ) with >89% retention. • Ag NP devices show >93% stability and ~99.7% efficiency after 15,000 cycles. • High energy (46–48 Wh/kg) and power (≈3780 W/kg) densities were achieved.