▎ 摘　　要

Graphene functionalization helps to improve the barrier property of graphene-reinforced coatings, however, it may also increase the electrical conductivity of coatings and result in galvanic corrosion between coating and metal. To demonstrate that fine-tuned functionalization of graphene is vital for its applications in metal protection, reduced graphene oxide (rGO) with various functionalization degree was precisely prepared. Compared with pristine rGO, rGO with a low functionalization degree possesses an enhanced corrosion promotion activity (CPA), and rGO with a high functionalization degree exhibits an inhibited CPA. Critical functionalization degree for inhibiting the CPA of rGO/epoxy nanocomposite coatings was determined. (C) 2019 Elsevier B.V. All rights reserved.