Polyaniline/g-C3N4 composites as novel media for anticorrosion coatings

In this paper, graphitic carbon nitride (g-C3N4) was first proposed for the pioneer application of anticorrosion coatings. Original g-C3N4 was facilely treated using HNO3 and the exfoliated g-C3N4 sheets (E-g-C3N4) were fabricated, and then, polyaniline/E-g-C3N4 composites (PANI/E-g-C3N4) as novel anticorrosive media were synthesized by chemical oxidative polymerization and devoted to the corrosion protection of coatings. The E-g-C3N4 sheets and PANI/E-g-C3N4 composites were characterized by X-ray diffraction, Fourier transform infrared, thermogravimetric analysis, and transmission electron microscopy. The anticorrosion properties of the samples prepared were investigated by electrochemical measurements including Tafel plots, electrochemical impedance spectra, and open-circuit potential. Accelerated corrosion tests of iron panels coated by PANI/E-g-C3N4 were performed in 3.5 wt% NaCl solution. Anticorrosive mechanism of PANI/E-g-C3N4 was discussed in detail. PANI/E-g-C3N4-3 fillers possessed superior corrosion inhibition than individual components on iron coatings, which was due to the synergetic effect of anticorrosion between E-g-C3N4 and PANI.