Green synthesis and electrochemical optimization of reduced graphene oxide for high-performance supercapacitors

Abstract

Supercapacitors are vital for next-generation energy storage, but achieving a balance between energy and power density remains a challenge. This study presents a green and scalable method for synthesizing reduced graphene oxide (rGO) using palm oil leaf extract as an eco-friendly reductant. Beyond sustainability, the work systematically investigates the influence of mass loading on electrochemical performance to identify an optimal configuration. Structural characterization reveals that the green reduction route promotes graphitization and reduces layer stacking, enhancing conductivity and ion transport. Among all samples, rGO-C exhibits the most balanced behavior, delivering a specific capacitance of 121.72 F g⁻¹ at 0.5 A g⁻¹, with 80.1 % retention over 1-5 A g⁻¹ and a high Cdl of 19.97 mF cm⁻². Notably, rGO-C also retains 90.7 % of its capacitance after 5000 cycles, demonstrating excellent long-term stability. These findings highlight the potential of agrowaste-derived reductants in fabricating high-performance, sustainable supercapacitor electrodes.