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[Display omitted] • A scalable and cost-effective production method of g-C3N4 coating is put forward. • The excited electrons can unidirectionally transferred from g-C3N4 to metal. • The excited electron can suppress the consumption of free electrons and remove rust. • The anti-corrosion mechanism of g-C3N4 is summarized via calculation and experiment. • g-C3N4 coating has superior long-term and remote anti-corrosion properties. Graphitic carbon nitride (g-C 3 N 4) has been considered as a candidate for anti-corrosion material owing to its barrier property and photoelectrochemical cathodic protection. However, the related mechanisms remain obscure and are not fundamentally investigated. Herein, g-C 3 N 4 coating on Q235 CS plate matrix can be simply made via conductive adhesive, which helps to achieve scalable production and high cost-effectiveness. It can also ensure the unidirectional transfer of excited electrons from g-C 3 N 4 to metal to prevent the consumption of free electrons on metal and reduce Fe 2 O 3 onto Fe. During the photocatalytic anti-corrosion process, the electron holes were simultaneously consumed via oxidizing water to achieve the balance between electron and hole transport. By combining theoretical calculation and experimental analysis, the anti-corrosion mechanisms of g-C 3 N 4 were systematically investigated. g-C 3 N 4 displayed superior long-term and remote anti-corrosion properties, especially for remote and difficult-to-reach areas, which will make it become a new generation of anti-corrosion 2D material with promising performance. [ABSTRACT FROM AUTHOR]

The ecofriendly waterborne alkyd coatings generally compromise the coating performance. Incorporation of polyaniline into alkyd to form nanocomposites can improve the corrosion resistance; however, the uniform distribution of polyaniline (PANI) within the alkyd resin remains a challenge. In this work, PANI is grafted onto epoxy functionalized phosphorylated poly (vinyl alcohol) (PPVA) with different side-chain configurations in order to improve compatibility and dispersion stability. These functionalized PPVA are synthesized using epichlorohydrin (ECIP) or γ-glycidyl methacrylate (GMA) as modifying agents, and respectively labeled as E-PPVA and G-PPVA. G-PPVA/PANI dispersion is stable even at a high PANI loading of 50%, while the maximum PANI loading for E-PPVA/PANI is only 30%. With the incorporation of G-PPVA/PANI into waterborne alkyd resins (AR), the coating resistance is increased by 7 orders of magnitude, and the corrosion inhibition efficiency is up to 99.9%. The coating with the incorporation of G-PPVA/PANI also demonstrates superior long-term corrosion resistance in comparison with that AR/E-PPVA/PANI nanocomposite coating. • PANI is grafted onto epoxy functionalized PPVA with different side-chain. • Compatibility and dispersion stability between PANI and PVA increased. • Improved the uniform distribution of PANI within the alkyd resin • The coating resistance is increased by 7 orders of magnitude. • The corrosion inhibition efficiency is up to 99.9%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Gemini surfactant (GS) is used to modify graphene oxide/polyaniline (GGO/PANI). • GS is more effective than cetyltrimethylammonium bromide (CTAB) surfactant. • GGO/PANI has better dispersion and compatibility in waterborne alkyd (WAR). • GGO/PANI/WAR nanocomposite film is more uniform. • GGO/PANI/WAR coating has reinforced long-term anti-corrosive property. Graphene oxide/polyaniline (GO/PANI) has been demonstrated to be an effective anti-corrosive nanofiller in polymer matrix, however, its hydrophobility restricts its application in waterborne polymer coatings. Here, cetyltrimethylammonium bromide (CTAB) and cationic gemini surfactant (GS) with the same constitutional unit as CTAB were adopted to fabricate CTAB modified GO/PANI (CGO/PANI) and GS modified GO/PANI (GGO/PANI). The incorporation of GS not only increased the intercalation degree of GO nanosheets but also functionalized as dopant to improve the electrochemical properties of PANI. The dispersibility and compatibility of GGO/PANI in waterborne alkyd resin (WAR) were also higher than that of CGO/PANI, resulting in the formation of more uniform nanocomposite coating. Compared with pure WAR, the coating resistance of GGO/PANI/WAR increased by 4 orders of magnitude, the corrosion density decreased by 3 orders of magnitude and the corrosion potential shifted from −0.72 V to −0.28 V. GGO/PANI/WAR also displayed enhanced long-term anti-corrosive properties in comparison with CGO/PANI/WAR. [ABSTRACT FROM AUTHOR]