Synthesis of Biomass-Derived Graphene Nanomaterials by Chemical Activation with KOH

This work introduces an environmentally sustainable and cost-effective strategy for synthesizing graphene nanomaterials from agricultural residues-walnut shells and apricot stones. The synthesis pathway combines desilication, controlled pre-carbonization, chemical activation with KOH, and mild exfoliation to produce few-layer graphene with a high degree of structural order. The process, conducted at 523-573 K for pre-carbonization and 1123 K for activation, enables the formation of graphene sheets with a specific surface area of approximately 1300 m²/g, carbon content of 80-90%, and average pore diameter below 100 nm. The materials were comprehensively characterized using SEM, TEM, Raman spectroscopy, and BET analysis. Raman spectra revealed an I_G/I_2D ratio of ~1.5-2 a.u., confirming the presence of 4-5 graphene layers. Compared to conventional biomass-derived graphene routes, the developed approach ensures enhanced porosity, higher graphitic ordering, and improved purity, demonstrating its strong potential for energy storage, adsorptive purification, and environmentally benign nanotechnology applications.