Graphene production from lignin via catalytic graphitization

Graphene-based materials are promising building blocks in nanotechnology due to their wide range of applications. This work focuses on a bottom-up approach in which graphene is obtained from lignin as an alternative carbon source, despite its high oxygen content. Studies on the reaction mechanisms governing graphene formation from lignin are scarce, and no reviews have been found on this topic, which highlights the novelty of the subject and the need for further research to support its development. The extent of graphitic domain formation depends mainly on parameters such as heating rate, annealing temperature, residence time, cooling rate, precursor characteristics, catalyst size and distribution, contact time between precursor and catalyst before annealing, and the presence and location of heteroatoms in the raw material. These factors are directly linked to key performance indicators of graphene quality (crystallinity, defect density, electrical conductivity, and structural homogeneity), which determine its suitability for advanced applications. Recent advances in conversion technologies make lignin-derived graphene a promising alternative. Scaling up lignin-to-graphene conversion requires addressing challenges related to cost-effectiveness, consistency, and product quality. This review highlights the key process factors that influence graphene quality and the barriers to industrial implementation. Additionally, it provides a comprehensive and critical analysis of the chemical evolution of lignin during catalytic pyrolysis for efficient graphene production, examines the catalytic pathways and transformation mechanisms involved, and defines the structure-property relationships essential for optimizing graphene yield and quality.