Adsorption mechanism of sulphide gas molecules on γ-Fe(1 1 1) surface: A density functional theory study

In this work, based on the first-principles method of density functional theory (DFT), the adsorption and dissociation paths of sulphide gas molecules on pure, vacancy-defective, Ni-doped and Cr-doped γ-Fe(1 1 1) surfaces have been studied systematically. The results show that H2S, COS, CH3SH can be spontaneously adsorbed on these four surfaces. Significant adsorption properties, changes in molecular structure and charge transfer indicate that chemical adsorption has taken place. The calculation results of the density of states show that the electronic orbitals between the sulphide molecules and the substrate surface are hybridized, indicating the formation of new chemical structures between them. Meanwhile, the chemical bonds of the three sulphide molecules are easy to break during the adsorption process, and the products are adsorbed on the surface in a more stable form. This work can provide theoretical guidance for anticorrosion and material selection of natural gas pipeline.