Formation mechanism of few-layer graphene adjacent to nanoscale zero-valent copper nanoparticles synthesized using kraft lignin as a sustainable aromatic-rich carbon resource

Abstract

Few-layer (three- to four-layer) graphene formed adjacent to zero-valent copper nanoparticles (FG-nZVCu) is a promising material for a wide range of applications, including catalysis, environmental remediation, energy storage, and functional composite development. Kraft lignin (KL) has attracted increasing interest as a sustainable and underutilized solid-state carbon precursor for the production of value-added graphitic materials. The effects of five different solvents on the solubility of KL and the dispersion uniformity of Cu²⁺ in the KL–solvent matrices were first investigated, followed by an evaluation of the effect of copper loading (10–40 wt% by KL weight) on the graphene layer number and particle size of FG-nZVCu, and subsequently the effects of in situ Cu-catalyzed thermal catalytic graphitization temperature (600–1100 °C) on FG-nZVCu formation. Experimental results show that few-layer turbostratic graphene structures become clearly observable adjacent to nZVCu particles at approximately 800 °C, and their degree of graphitization increases as the temperature increases to 1100 ° C. This behavior suggests that the formation mechanism involves Cu-assisted aromatic carbon ring surface rearrangement of aromatic carbon fragments decomposed from KL during thermal treatment. Additionally, the use of the moderately polar solvent tetrahydrofuran (THF) to facilitate KL dissolution enables more uniform dispersion of nZVCu particles within the KL matrix. An optimal Cu loading of 20 wt% results in uniformly distributed nZVCu particles with an average size of 27.3 nm.

Citation

Guo, Sijin; Yan, Qiangu; Kim, Yunsang; Mlsna, Todd; Street, Jason Tyler; Cai, Zhiyong; Zhang, Jilei. 2026. Formation mechanism of few-layer graphene adjacent to nanoscale zero-valent copper nanoparticles synthesized using kraft lignin as a sustainable aromatic-rich carbon resource. Journal of Materials Chemistry A. 14(55): 37991-38001. https://doi.org/10.1039/d6ta04482d.