Low-cost synthesis of large graphene oxide flakes by the total oxidation of large natural graphite flakes

• • Complete oxidation of large graphite flakes (up to 1 mm) achieved without fragmentation, as directly evidenced by in-situ monitoring, enabling production of LGO with average lateral sizes up to 116.2 μm. • • Minimizing H2SO4 volume to create a semi-solid state elevates oxidizer concentration, reducing reagent consumption while achieving full oxidation of 200-, 100-, and 50-mesh graphite. • • Optimized reaction temperature balances Mn(VII) self-decomposition and graphite oxidation, ensuring complete oxidation with 100% conversion and yield exceeding 165%. • • Scalable and cost-effective synthesis route for LGO, with average sizes of 27.3, 58.7, and 116.2 μm from 200-, 100-, and 50-mesh graphite, respectively, suitable for industrial production.