Fabrication of nitrogen doped graphene oxide coatings: experimental and theoretical approach for surface protection

In this work, we present a simple strategy of fabricating an N-doped graphene oxide (N-GO) coating on stainless steel (SS) for protective applications. Electrochemical, surface analytical and quantum chemical techniques were employed to characterize the synthesized coatings on the SS surface. Graphene oxide (GO) and reduced graphene oxide (rGO) coatings on SS were adopted for comparison. The downshift of the G band in the Raman spectra of N-GO corroborated the incorporation of N atoms and the deconvoluted spectra of N1s revealed that N-GO coatings retain three types of nitrogen. The influence of N doping on the surface roughness and hydrophobicity of GO was investigated using surface topographic and contact angle measurements. An electrochemical corrosion study on the coatings indicated that N doping of GO enhances the corrosion resistance of SS in 3.5% NaCl solution more than GO and rGO. In order to describe the underlying mechanism, the adsorption energies of GO coatings with SS were computed using molecular dynamics simulation (MDS). The MDS results revealed that all the coating systems adsorbed in a parallel orientation on the Fe surface. N-GO coating exhibited the strongest and the most stable chemisorbed interaction on SS when compared to GO and rGO.