Hierarchical synthesis of multi-layer graphene-like and nitrogen-doped graphitized carbon from dead leaf biomass for high-performance energy storage and CO₂ capture

Background

This research presents an integrated approach to convert dead leaf biomass into graphene-like materials through a combination of carbonization, activation, graphitization, and graphenization. Unlike conventional techniques that involve separate and a few sequential steps of carbonization, activation, graphitization, and graphenization to treat biomass, we executed the above four processes hierarchically.

Methods

DG (multi-layer graphene-like) and NG (nitrogen-doped graphitized carbon) were synthesized via hydrothermal and solvothermal impregnation followed by pyrolysis. Characterization was performed using Raman spectroscopy, BET analysis, XRD, XPS, HR-TEM, and FESEM. CO₂ adsorption was measured using TGA, and Energy storage performance was evaluated through cyclic voltammetry, galvanostatic charge-discharge measurements, electrochemical impedance spectroscopy, and long-term stability tests, all conducted using a three-electrode configuration.

Significant Findings

DG had a surface area of 1400 m²/g, CO₂ adsorption of 50 mg/g, and a specific capacitance of 184 F/g at 1 A/g. NG showed a surface area of 947 m²/g, CO₂ adsorption of 70 mg/g, and a specific capacitance of 206 F/g at 1 A/g. These results highlight the potential of biomass-derived graphene-like materials for sustainable CO₂ capture and energy storage.