Conversion of Renewable Lignocellulosic Biomass-Derived Nanocellulose into Graphene via Pyrolysis and High Shear-Mediated Exfoliation

Graphene is extensively researched due to its diverse range of applications and remarkable properties. Current production methods such as sonication and chemical vapor deposition (CVD) are energy-intensive and unsustainable, restricting its industrial use. The vortex fluidic device (VFD) is a thin film processing platform that rapidly spins a tube to generate high shear forces and offers a low-cost and sustainable method for graphene production. However, previous studies on exfoliation are limited to utilizing graphite as the feed, which not only is unsustainable but also generates high carbon emissions due to mining processes. In this study, nanocellulose crystal (NCC), a sustainable material derived from lignocellulosic biomass, is used as the precursor for graphene production. The NCCs are first pyrolyzed at 500–800 °C at 5 °C min⁻¹ for 60 min and then converted to graphene in the VFD using only water as the solvent. The biochar properties significantly impact the exfoliation degree, and 600 °C is the optimal pyrolysis temperature. The Earth's magnetic field and rotation direction also affect the VFD processing. The graphene shows a relatively high quality with an I_D/I_G ratio of 0.60, an I_2D/I_G ratio of 0.15, and transmission electron microscopy confirming <6 layers. This process offers a sustainable route for graphene synthesis using renewable biomass feedstock.