Synthesis of reduced graphene oxide (rGO) films onto carbon steel by cathodic electrophoretic deposition: Anticorrosive coating

- Ca2+ allows the electrophoretic deposition of GO onto the cathode.
- A cross-linker effect occurred between Ca2+ and GO's carboxylic groups.
- Electrochemical reduction of GO and its deposition was achieved simultaneously.
- The GO reduction by hydrogenolysis/hydrogenation reactions is suggested.
- The rGO film reduces up to three times the corrosion of carbon steel.

The use of graphene based materials as anticorrosive coatings for the protection of metals is still a controversial subject worthy of debate. The electrophoretic deposition (EPD) is one of the most used techniques to produce anticorrosive coatings onto metals, including graphene oxide (GO) and reduced graphene oxide (rGO) coatings. However, for the specific case of carbon steel's protection, EPD of GO has not achieved positive results. This work proposes a variation in the EPD process of GO, which consisted in changing the GO's charge to positive values by adsorbing Ca2+, allowing the electrophoretic deposition of GO onto the cathode (cEPD). The achieved film was characterized by scanning electron microscopy (SEM), Raman Spectroscopy, X-ray photoelectron spectroscopy (XPS) and evaluated electrochemically. The coating diminished by three times the corrosion of carbon steel: the corrosion current was reduced from 11.83 to 4.14 mA cm−2, the charge transfer resistance incremented from 84 to 406 Ω and a shift in the corrosion potential from −0.72 to −0.61 V was observed. An electrochemical reduction mechanism of GO involving hydrogenation/hydrogenolysis reactions is suggested as the main reason to achieved an effective coating by cEPD in comparison to the films produced by an anodic EPD.

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