Computational evaluation of multifunctional nanostructured inhibitors to control microbiologically influenced corrosion: DFT calculations and MD simulations

Corrosion inhibition mechanism of two multifunctional nanostructured inhibitors, including graphene oxide/silver nanostructure (GO-Ag) and carbon quantum dots/copper nanoparticles (CQDs-Cu) on API 5 L Grade X60 PSL2 surface (10 mm × 10 mm × 3 mm) was investigated by quantum chemical calculation and molecular dynamics (MD) simulations. Global reactivity parameters such as E HOMO , E LUMO , energy gap, etc., have been studied to investigate their relative corrosion inhibition performance. Local reactivity parameters of both inhibitor molecules have been analyzed through Mulliken population distribution and Fukui functions. Moreover, the adsorption behavior of the multifunctional nanostructured inhibitor’s molecule on the Fe (1 1 0) surface has been studied using MD simulations. The high E HOMO and low value of E LUMO indicated the existence of doner-acceptor sites on the inhibitor’s molecule, resulting in the high tendency of CQDs-Cu and GO-Ag to react with Fe and create a protective layer. The result of interaction energy, diffusion coefficient, and fractional free volume indicated the formation of a compact film on the surface of Fe by CQDs-Cu and GO-Ag, tackling the movement of corrosive particles towards the Fe surface. The corrosion inhibition mechanism of multifunctional nanostructured inhibitors was finally suggested based on experimental and theoretical studies. Graphical abstract