Slab model studies of H2S adsorption/dissociation and diffusion on pristine FeS(001) surfaces and FeS(001) surfaces with pre-adsorbed X atoms (X = H, O, and S)

Abstract

Dispersion-corrected density functional theory (DFT-D2) was used to calculate the adsorption/dissociation mechanisms of H2S and diffusion mechanism of H atoms on a pristine FeS(001) surface and on FeS(001) surfaces with various pre-adsorbed atoms. The calculation results showed that the pre-adsorption of atoms was beneficial to H2S adsorption/dissociation, and the first-order dissociation energy barrier (Ea) of H2S on the FeS(001) + S surface is reduced from 2.06 eV on the pristine surface to 0.97 eV. Additionally, the pre-adsorption of an H atom was found to not only reduced the diffusion Ea of H atoms (0.62 eV), but also shortened the diffusion path (P3→P4). Finally, calculations indicated that the thermodynamic conditions on the pristine FeS(001) surface were conducive to the generation of H2 molecules (Ea = 0.08 eV; reaction heat (ΔE) ΔE = −1.54 eV). These results increase our understanding of H2S adsorption and dissociation and H atom diffusion on different FeS (001) surfaces, and provide a theoretical basis for corrosion prevention. This work also has reference value for the study of the mechanisms by which molecules/atoms in the environment influence related systems.

Keywords

• DFT-D2
• Mackinawite FeS(001) surface
• Pre-adsorbed atoms
• Adsorption/dissociation process
• Diffusion mechanism