Sustainable synthesis of hierarchical porous carbon from deoiled camphor leaves via cellulase hydrolysis and potassium bicarbonate activation for high-performance supercapacitors

Abstract

Hierarchical porous carbon with a three-dimensional (3D) graphene-like morphology was successfully synthesized using a sustainable approach. Camphor leaf biomass, after essential oil extraction, was employed for the first time as the raw material and co-treated with cellulase and potassium bicarbonate (KHCO₃). Cellulase treatment disrupted the lignocellulosic framework, which enhanced the pore expansion and facilitated the penetration of KHCO₃, leading to the development of abundant micro- and meso-porous structures. The resulting porous carbon (CE-K-PC) exhibited a high surface area (2401 m²·g⁻¹), a large pore volume (1.43 cm³·g⁻¹), and a relatively high mesoporous ratio (0.78). Electrochemical experiments revealed outstanding efficiency, achieving a specific capacitance of 232 F·g⁻¹ at 1 A·g⁻¹ in 1 M KOH. A symmetric supercapacitor assembled with two CE-K-PC electrodes demonstrated excellent stability, retaining 97.5 % of its initial capacitance following 10,000 cycles at 5 A·g⁻¹. These findings demonstrate the potential of graphene-like biocarbon prepared using cellulase hydrolysis followed by KHCO₃ activation for future sustainable energy storage applications.