Sustainable Synthesis and Characterisation of Tyre Char-Based Graphene Oxide Via Microwave-Assisted Pyrolysis

Abstract Around one billion tyres accumulate annually, creating environmental and economic challenges. This study explores converting scrap tyres into graphene oxide via a two-step microwave-assisted pyrolysis process, providing a sustainable alternative to costly, resource-intensive traditional GO production from graphite. Microwave irradiation is highlighted for its rapid, energy-efficient heating of microwave-absorbing materials. The process involves microwave pyrolysis of waste tyres (rubber) with ferric chloride (FeCl 3 ) as a catalyst, followed by concentrated sulfuric acid (H₂SO₄) treatment. The resulting tyre char-based GO (TC-GO) was characterised using X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The morphology of TC-GO appeared sheet-like, with a crystalline size measured at 26.09 nm. Raman analysis showed distinct D (1344 cm −1 ) and G (1590 cm −1 ) bands with an I D /I G ratio of 0.99, indicating a graphitic structure. XPS confirmed a carbon content of 54.81% and oxygen at 28.52%, while SEM and TEM revealed disordered, overlapping sheets with wrinkled edges, consistent with poor crystallinity from SAED patterns. This study demonstrates the feasibility of producing GO from tyre char (TC), presenting a cost-effective and sustainable alternative. In particular, the synthesised TC-GO shows promise for future use in cement mortar, with potential improvements in mechanical and durability properties that should be studied further. The resulting TC-GO holds promise for applications in composite materials and cement additives, offering an innovative solution for waste tyre management and advancing GO-based technologies. Graphical Abstract