Graphene oxide coatings on amino acid modified Fe surfaces for corrosion inhibition

An effective solution for corrosion protection of metallic carbonyl iron (CI) substrates in strong saline environment (3 M KCl) is demonstrated in this work. A thin layer coating of graphene oxide (GO) sheets enhances the corrosion inhibition behavior of amino acids that are directly grafted on metallic iron surfaces. The combined effect of GO and the corrosion inhibiting layer such as para-aminobenzoic acid (PABA), glycine, or alanine drastically improves the corrosion inhibition efficiency, in comparison to any of the single-layer coating, without considerably increasing the coating layer thickness. The microscopic origin of the corrosion protection efficiency of these layers is explained by the physical arrangement of the inhibitor molecules and the integrity of the GO sheets. According to our results, although a single layer of alanine provides better corrosion protection than that of a single layer of glycine or PABA, an additional coating of GO sheets effectively enhances the corrosion protection efficiency multifold. This comes with a concomitant advantage that glycine is economically much cheaper than alanine. Hence, our study demonstrates an economical way to achieve excellent efficiency in corrosion inhibition for metallic surfaces, making our technology exceptional for their direct implementation in environmental and industrial applications.