Inevitable crumpling and folding of graphene in coating matrix restricts the enhancement of corrosion protection properties of graphene-based coatings. Herein, reduced graphene oxide with self-unfolded morphology (S-rGO) and crumpled morphology (C-rGO) were prepared. Compared with C-rGO, S-rGO exhibits a higher performance in enhancing the corrosion protection properties of epoxy coating because S-rGO possesses larger effective aspect ratio and projected area in the direction perpendicular to the diffusion path of aggressive species so that its impermeable domains can force aggressive species to over come the coating matrix via migrating along longer diffusion paths. (c) 2020 Elsevier B.V. All rights reserved.