Comprehensive insight into the interfacial adsorption mechanism of pyridine derivatives by molecular dynamics simulations, GFN-xTB and first-principles calculations

Abstract

The application of computational chemistry methods is becoming increasingly prosperous in the interfacial adsorption study of corrosion inhibitors. In this work, three typical computational chemistry methods, molecular dynamics (MD) simulations, GFN-xTB and first-principles calculations, were employed to investigate the interfacial adsorption processes of four pyridine derivatives (CP, ACP, DPA and ABOP) on Fe surface. With related to the measured corrosion inhibition efficiencies of the four pyridine derivatives for mild steel in HCl solution by weight loss and electrochemical tests, the calculated results by these three methods were compared in terms of the adsorption configurations, bonding mode, and the adsorption strength (adsorption energy). Based on the radical distribution function (RDF) from MD simulations, it is only roughly inferred that pyridine derivatives can chemically adsorb on Fe surface. While both GFN-xTB and first-principles calculations indicate that the adsorptions of the four pyridine derivatives are through the N and unsaturated C atoms. In particular, compared to DPA and ABOP molecules, the cyano groups (−CN) of CP and ACP molecules exhibit outstanding adsorption capacity, which endow CP and ACP with better inhibition performances.