Sustainable energy storage: leaf waste-derived activated carbon for long-life, high-performance supercapacitors.

Biomass waste-derived activated carbon has a wide range of applications, including air and water purification, gas separation, energy storage, and catalysis. This material has become increasingly popular in recent years as a result of the growing demand for sustainable and eco-friendly materials. In this study, leaf waste-derived activated carbon has been investigated as an electrode material for high-performance supercapacitors. The dried leaves were first carbonized using FeCl and then activated using KOH to increase their surface area and pore structure at different temperatures. The activated carbon prepared at 725 °C has shown a high specific capacitance of 521.65 F g at a current density of 0.5 A g and also achieved an energy density of 17.04 W h kg at a power density of 242.50 W kg in the 6 M KOH electrolyte. Significantly, it has demonstrated remarkable electrochemical cycling stability, retaining 96.60% of its initial capacity even after undergoing 10 001 cycles at a scan rate of 500 mV s. The superior electrochemical performance of the activated carbon can be attributed to its high surface area of 1232.63 m g, well-distributed pore size, and excellent degree of graphitization, which all facilitate the rapid diffusion of ions and enhance the accessibility of the electrolyte to the electrode surface. Hence, this study provides a promising route for utilizing waste biomass as a low-cost, sustainable electrode material for energy storage devices.