Toward understanding the adsorption mechanism of large size organic corrosion inhibitors on an Fe(110) surface using the DFTB method

Abstract

One of the effective methods developed to inhibit the corrosion of steel is the use of organic molecules as corrosion inhibitors. In particular, the design and synthesis of large size organic corrosion inhibitors draws more and more attention. Unfortunately, an atomic-level insight into the inhibition mechanism is still lacking, and regular density functional theory method is found to be inefficient in dealing with large inhibitor-metal adsorption systems. Given this background, in this work, density functional based tight binding (DFTB) approach was used to investigate the adsorption properties of three large size inhibitors (i.e., chalcone derivatives) on an iron surface. The molecular activity of free chalcone derivatives was studied by means of Frontier molecular orbital theory. The growth characteristics of a-Fe habits were observed using the "Morphology" software. Some adsorption parameters such as charge density difference, density of states, and changes of molecular orbital were described in detail. The present study is helpful to understand the anticorrosive mechanism of similar organic inhibitors and provides a feasible way to develop novel corrosion inhibitors.

Electrochemical and adsorption behaviors of thiadiazole derivatives on the aluminum surface

“…23,25 Furthermore, Fukui function offers a useful approach to predict electron transfer reactivity, which helps researchers to better understand the electronic properties of the functional groups and conrm the main active sites of a molecule. 22,26,27 Therefore, due to the similar structure of thiadiazole and its derivatives, this study focuses on 2,5-bis (octyldithio)-1,3,4thiadiazole (BODTA) and aims to present new insights into its electrochemical and adsorption behaviors on aluminum via experimental and theoretical methods. The morphology, elements and compounds on the aluminum surface were characterized.…”

Density-functional tight-binding: basic concepts and applications to molecules and clusters

“…More recently, the development of new DFTB parameters has also made it possible to study the adsorption of organic molecules on metal surfaces. One can for example mention a study of the adsorption of a corrosion inhibitor (chalcone derivative) on a Fe (110) surface in which the π molecular orbitals were found to play a major role in the adsorption phenomenon [312]. DFTB was also developed in order to study adsorption of organic molecules on carbon surfaces, for example transition metal complexes (porphyrin and porphycene) on graphene [313] or small molecules (H 2 O, CH 4 , NH 3 ) on defective carbon nanotubes which were all found to physisorb on the nanotubes, except NH 3 which also chemisorbs [314].…”

Organic Corrosion Inhibitors

“…Presence of the heteroatoms with lone pair of electrons like nitrogen, oxygen, sulfur or phosphor as well π-electrons of multiple bonds or aromatic rings enhance adsorption phenomena [74]. Chemisorption involves transfer or sharing of unbounded electrons between the inhibitor molecule and the metal surface [75]. The order of corrosion inhibition is the reverse order of the electronegativity of these atoms…”

“…• compounds containing nitrogen: amines [77], pyridine derivatives [74,75], quaternary ammonium salts [80], triazole derivatives [81], Schiff base [82], amino acids [64] and indazole [83],…”