Graphitized LignoMOF Hybrids as Emerging Precious Metal‐Free Carbon Materials for Supercapacitor Electrodes

ABSTRACT Developing sustainable and conductive carbon materials from renewable biomass resources is an important challenge for next‐generation electrochemical energy storage systems. In this work, lignin and metal‐organic framework (LignoMOF) hybrids derived from alkali lignin and ZIF‐8 were engineered and converted into conductive porous carbon materials via iron‐assisted catalytic graphitization. The structural and surface characterizations conducted provided compelling evidence that moderate Fe incorporation fosters partial graphitization, retention of nitrogen from the MOF precursor, and the establishment of conductive graphitic domains without significant pore obstruction. Electrochemical assessments performed in a 1 M KOH electrolyte employing cyclic voltammetry, galvanostatic charge‐discharge and EIS techniques demonstrated that the Fe‐modified electrodes exhibit a predominance of electric double‐layer capacitance behavior, coupled with improved charge storage capacity and rate performance. Notably, among the tested series, gFe ₁₀ Lig@ZIF‐8 achieved the highest areal capacitance of 215 mF cm ⁻² at 1 mA cm ⁻² , together with a capacitance retention of 89.12% after 5000 cycles and minimal iR drop. The optimized electrode also outperformed several reported biomass‐derived and laser‐written carbon electrodes operating under comparable alkaline conditions. Excessive iron loading resulted in diminished capacitive performance, thereby underscoring the necessity of achieving an equilibrium between catalytic graphitization and pore accessibility.