Unraveling the Carbon Corrosion Mechanism during Aqueous Electrochemical Anodic Exfoliation for Graphene Production

Aqueous electrochemical anodic exfoliation offers a promising route for scalable graphene production owing to its environmental friendliness and green nature. However, carbon corrosion causes substantial carbon loss, hindering its practical application. Herein, a custom-designed electrolyzer with the physically isolated anode and cathode was developed to enable unambiguous tracking of carbon corrosion pathways. Through combined experimental and theoretical investigations, a multi-pathway carbon corrosion mechanism is revealed. The total carbon loss rate increases with decreasing voltage or increasing temperature, reaching 54% at 15 V and 70 °C, with low graphene selectivity (7.0%) and yield (5.7%). Notably, carbon corrosion primarily yields CO2 and CO, accounting for up to 89% of total carbon loss with a CO2:CO volume ratio of 7.4–9.7:1, along with minor hydrocarbon and soluble organic species. ·OH radicals, coexisting with SO4·–, serve as the key active species driving carbon oxidation. DFT calculations reveal that the ·OH-mediated oxidation of edge carbon exhibits a lower energy barrier via hydroxylation–oxidation–cleavage to form CO/CO2 than that of in-plane defective carbon, accompanied by more significant charge transfer and electronic structure modulation after hydroxyl adsorption. This work elucidates the multi-pathway carbon corrosion mechanism and provides insights for minimizing carbon loss in sustainable graphene production by electrochemical exfoliation.