DFT and microkinetic investigation of oxygen reduction reaction on corrosion inhibition mechanism of iron surface by Syzygium Aromaticum extract

Abstract

Corrosion of iron is an important and serious problem in materials. So far, many studies have been carried out to overcome the corrosion of iron. However, first-principle studies at the atomic level of iron corrosion processes based on electrochemical reactions are still very limited. Investigations based on electrochemical oxygen reduction reactions (ORR) are very important, because naturally corrosion is an electrochemical process. In this paper, the corrosion mechanism of the Fe(110) surface and the mechanism of corrosion inhibition by eugenol based on the electrochemical ORR are investigated using combinations of DFT and microkinetic models. We show that the ORR activity starts when the iron surface is covered by O atoms until the monolayer coverage is almost full, which indicates that the first stage of the iron corrosion process is not direct oxidation. After the iron surface is covered by O atoms, the corrosion process will begin with the occurrence of a proper ORR rate. In the presence of eugenol as a green corrosion inhibitor, the ORR activity is significantly lower, which also means that the corrosion rate is inhibited. This is confirmed by the higher overpotential value and lower TOF. In addition, the surface coverage is no longer dominated by free sites. Overall, our research provides new insights into designing green corrosion inhibitors for iron surface.