▎ 摘　　要

NOVELTY - Preparing monolayer graphene oxide comprises (a) uniformly mixing hydrogen peroxide and concentrated sulfuric acid, when the mixed solution drops to room temperature, adding flake graphite, soaking at room temperature, (b) washing and suction filtering with deionized water, and drying to obtain expanded graphite, (c) mixing expanded graphite and potassium permanganate evenly, slowly adding concentrated sulfuric acid and concentrated phosphoric acid dropwise under ice bath conditions to carry out secondary oxidation intercalation reaction, heating and stirring, adding ice water and hydrogen peroxide, and using deionized water for centrifugal washing until neutral, and freeze-drying to obtain a single-layer graphene oxide with a sheet diameter of 438 μm. USE - The method is useful for preparing monolayer graphene oxide. ADVANTAGE - The method overcomes the problem that the graphene oxide sheets prepared by the existing preparation process are easily broken.