First‐principles based theoretical investigation of the adsorption of alkanethiols on the iron surface: A DFT-D3 study

Abstract

The search for novel corrosion inhibitors is a never-ending and challenging task. Computational studies are fundamental to assessing the interaction of inhibitor molecules with metals, thus opening the way to design new inhibitors with specific characteristics. Herein, first-principles DFT-D3 calculations were performed to simulate the bonding of three alkanethiols, namely 11-mercaptoundecanoic acid (MDA), decanethiol (DT), hexanethiol (HT) with the iron surface Fe(110). The interaction energies obtained from different adsorption systems predicted this adsorption strength: MDA > DT > HT. The perpendicular adsorption geometries were found to be more stable than other adsorption modes. However, all adsorption configurations showed covalent interactions between sulfur atom and iron surface. Electron density difference (EDD) plots and projected density of states (PDOS) further confirmed the electron-donation and back-donation synergic interactions between interactive systems. This study showed that alkanethiols with a long carbon chain and an end-functional group had increased charge transfer and bonding with the bare iron surface, i.e., Fe(110).