Assessing corrosion inhibition characteristics of hydrazone derivatives on mild steel in HCl: Insights from electronic-scale DFT and atomic-scale molecular dynamics

Abstract

Abstract Understanding and predicting adsorption capacities of corrosion inhibitors on the metal surface is of great significance for designing high-performance inhibitor molecules. Herein, a computational methodology, which utilizes molecular dynamics (MD) simulation and Density Functional Theory (DFT), was adopted to investigate the inhibition performance of four hydrazone derivatives (HDZ1-HDZ4) on mild steel corrosion in acidic medium. The adsorption of the four compounds on the Fe (110) surface was studied and analyzed using global and local reactivity descriptors, molecular electrostatic potential (MEP), MD, and radial distribution function (RDF). MD results showed that the binding energy of investigated compounds with the iron surface follows the order of HDZ1 (912 kJ/mol) > HDZ2 (857 kJ/mol) > HDZ3 (801 kJ/mol) > HDZ4 (711 kJ/mol). Furthermore, the fractional free volume (FFV) and the interaction energy were selected for the evaluation of the diffusion behavior of hydronium and chloride ions inside inhibitor films. The results showed that both factors had a vital effect on the diffusion coefficient of corrosive particles. All results proved that inhibitor molecules having a high electron-accepting ability interact actively with the iron surface. Additionally, a direct relationship was observed between the experimentally determined inhibition efficiency and the adsorption strengths obtained from DFT and MD studies.