Precursor engineering for rapid joule heating synthesis of graphitic carbon from peanut shells

Flash Joule Heating (FJH) is a rapid, energy-efficient route to convert carbon feedstock into graphitic structures, yet the structural quality of flash graphene (FG) remains highly sensitive to the nature of the precursor. In this study, we demonstrate that precursor engineering enables control over graphitic ordering of FJH-synthesised graphene from peanut shells (PS). The study isolated the effects of thermal pretreatment and flash voltage on FJH outcomes, establishing clear relationships between precursor structure, FJH parameters, and graphitic ordering of FG during ultrafast heating. PS were either pretreated with conventional furnace, rapid Indirect Joule heating (IJH), or low-voltage pulse conditioning prior to FJH from 90 V - 180 V. Comprehensive characterisation by Raman, XPS, XRD, GC, TGA, and HRTEM/SAED, together with in-situ electrical and thermal monitoring, established how precursor engineering controls graphene formation. The intensive IJH (short 500–1000°C steps with 60 V conditioning) produced a homogeneous, conductive precursor that converted under a single FJH event to few-layer turbostratic graphene (I_2D/I_G = 2.04). In contrast, prolonged furnace carbonisation yields dense, restacked lamellar structures that exhibit limited conversion during FJH. Reactive molecular dynamics (MD–ReaxFF) simulations reproduced the observed sequence of deoxygenation, aromatic ring formation and edge growth under rapid heating. These results identify precursor engineering as one of the critical factors for achieving rapid, energy-efficient synthesis of high-quality turbostratic graphene from biomass via Joule heating.