▎ 摘　　要

NOVELTY - Separating graphene oxide, comprises (a) preparing a graphene oxide aqueous solution, (b) adjusting acidity by adding acid or base to the graphene oxide aqueous solution, and (c) separating supernatant and lower layer solution of the graphene oxide aqueous solution. USE - The method is useful in separating graphene oxide for producing graphene coated steel sheet (all claimed). ADVANTAGE - The method produces monodisperse graphene oxide with high yield through simple process, and provides steel sheet having large-area coating surface. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for producing graphene coated steel sheet, comprising (i) preparing supernatant or lower layer separated solution by the above method, (ii) separately separating the graphene oxide contained in supernatant solution or the lower layer solution, and mixing the separated graphene oxide with organic resin to obtain a graphene oxide coating solution, (iii) coating the graphene oxide coating solution on a base steel sheet to form a graphene oxide coating layer, and (iv) heating the base steel sheet to reduce the graphene oxide coating layer.