In the actual environment,
impurity atoms significantly affect
the adsorption/dissociation of gas molecules on the substrate surface
and in turn promote or impede the formation of subsequent products.
In this study, we investigate the effects of three kinds of impurity
atoms (H, O, and S) on the adsorption/dissociation of hydrogen sulfide
(H2S) and hydrogen (H) diffusion processes by using the
density functional theory method. We found that impurity atoms can
change the charge density distribution of the surface and thus affect
the adsorption/dissociation process of H2S. The existence
of a H atom reduces the dissociation barrier of H2S. The
adsorption site of H2S near the O atom is transferred from
the bridge site to the adjacent top site and the first-order dissociation
barrier of H2S is 0.07 eV, which is prominently lower than
that of the pristine surface (0.28 eV). The presence of a S atom transfers
the adsorption site of H2S to a farther bridge site and
effectively affects the dissociation process of H2S. Both
O and S atoms hinder the dissociation process of HS. Moreover, the
diffusion process of H atoms to the subsurface can be slightly impeded
by the O atom. Our work theoretically explains the influence mechanism
of impurity atoms on the adsorption/dissociation of H2S
and H diffusion behavior on the Fe(100) surface.
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