Enhanced anti-corrosion performance of epoxy coating with the incorporation of novel carbon nitride/PANI fillers

Background Corrosion, being a pervasive and inevitable natural occurrence, poses a grave threat to engineering equipment, human well-being, and the environment. Polyaniline (PANI) is an excellent anti-corrosion filler that enhances the corrosion resistance of steel surface. The traditional PANI preparation methods are chemical oxidation or electrochemical oxidation at low temperature, and the reaction conditions are harsh and easy to cause energy waste. Methods Novel ECN@PANI composite fillers were synthesized using nitric acid etched g-C 3 N 4 (ECN) as photoinitiator at room temperature. ECN@PANI/WEP coatings were prepared by using synthetic ECN@PANI composites as corrosion inhibitors and waterborne epoxy resin (WEP) as raw materials. ECN@PANI/WEP coatings were then hydrophobically modified with polydimethylsiloxane (PDMS) to yield ECN@PANI/HWEP coatings. The comprehensive structures and optical properties were thoroughly evaluated through Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Electrochemical Impedance Spectroscopy (EIS) and Diffuse Reflectance Spectroscopy (DRS) studies. Significant findings ECN@PANI composite fillers with excellent anticorrosive properties were prepared by photocatalytic polymerization using ECN as a photoinitiator. XPS and XRD results show that ECN@PANI/HWEP coating forms a dense passivation layer (Fe 3 O 4 ) on Q235 steel surface, which reduces the corrosion of steel to the maximum extent; ECN@PANI/HWEP produces active substances under light, which oxidize, fracture, and degrade the cell wall when in contact with the cells, resulting in a coating with better anti-algae properties; and the ECN@PANI/HWEP coating refracts part of UV rays and converts the remaining UV rays into heat to achieve excellent UV resistance properties. Combining outstanding UV resistance and anti-algae properties, the ECN@PANI/HWEP coating ensures long-term corrosion protection.