Accelerating corrosion inhibitor discovery through computational routes: a case of naphthalene 1-thiocarboxamide

The conventional approach to the discovery of corrosion inhibitors is time-consuming and requires a significant amount of resources. In the present study, we highlight the use of a first principles DFT-based approach to expedite the rational design and discovery of corrosion inhibitors for mild steel in acidic media. From among various sulfur containing molecules shortlisted based on quantum chemical descriptors, naphthalene 1-thiocarboxamide (NTC) is found to have the lowest ELUMO and Egap, suggesting best corrosion inhibition. Subsequently, explicit adsorption studies reveal strong chemisorption of NTC onto the Fe (001) surface, characterized by a plethora of Fe-C/N/S covalent bonds. DFT Surface coverage studies additionally indicate the formation of a compact monolayer of NTC on the Fe surface. Gravimetric, potentiodynamic polarization, and Electrochemical Impedance Spectroscopy studies, all confirm NTC as a remarkable inhibitor for mild steel in 1 N HCl at both room and elevated (60 °C) temperatures even at merely 1 mM concentration.