Poorly conductive electrochemically reduced graphene oxide films modified with alkyne chains to avoid the corrosion-promoting effect of graphene-based materials on carbon steel

Recently, the discovery of the corrosion-promoting effect of graphene has hindered the progress in the use of graphene-based materials as anticorrosive coatings. This work proposes to avoid the corrosion-promoting effect by the introduction of favorable defects to electrochemically reduced graphene oxide (ErGO), which consisted in the hydrogenation of sp2 domains during the removal of O-groups in graphene oxide, favoring sp3 domains and low conductivity. The ErGO films were subsequently modified with 4-pentyonate chains to obtain films with lower conductivity and enhanced hydrophobicity (HrGO). The alkyne chains were bonded to the remaining sp2 domains in ErGO by a simple electrochemical process. Both films were characterized by FT-IR, XPS, Raman spectroscopy and electrochemical methods. As anticorrosive coating, the HrGO film achieved a 4-times decrease in the corrosion current and showed a longer lifetime in comparison to the ErGO film, and an 18-times decrease compared to the bare carbon steel. According to the galvanic current measurements, neither of the films presented a corrosion-promoting effect, which was attributed to their low conductivity, 13 and 1.3 S cm−1 for ErGO and HrGO, respectively. These results show that the corrosion promoting effect of graphene can be avoided using correctly engineering ErGO with adequate defects.