LAUSR

Abstract Density functional theory is employed to investigate H 2 S adsorption on perfect, defect, step Pd(111) and Pd/γ-Al 2 O 3 (110) surfaces at different coverage. The adsorption of one and two H 2 S molecules are completely dissociative adsorption on the Pd(111) surfaces; three H 2 S molecules adsorption is mixed adsorption on the prefect and defect Pd(111) surfaces, and completely dissociative adsorption on the step Pd(111) surface, while the most stable adsorption is partially dissociative adsorption on γ-Al 2 O 3 (110) and Pd/γ-Al 2 O 3 (110) surfaces. The adsorption energies of H 2 S on the defect and step Pd(111) surfaces are stronger than those on the perfect Pd(111) surface, and the existence of defect and step can enhance the H 2 S adsorption activity of Pd adsorbents at 0.11 ML. It is found that the γ-Al 2 O 3 supported single Pd atom reduces H 2 S adsorption activity at low coverage, and γ-Al 2 O 3 support enhances the activity of Pd for H 2 S adsorption at high coverage. The results show that the total adsorption energies increase as the coverage increases on Pd surfaces, and the stepwise adsorption energies decrease as the coverage increases. The stepwise adsorption energies show that the full monolayer H 2 S adsorption on the various surfaces is thermodynamically favorable.