Density functional study on the resistance to sulfur poisoning of Ptx (x = 0, 1, 4 and 8) modified α-Mo2C(0001) surfaces

Abstract

The tolerance of sulfur poisoning of α-Mo₂C(0001) surfaces with different Pt coverages is investigated combining the density functional theory (DFT) results with thermodynamics data using the ab initio atomistic thermodynamic method. It is found that on Mo₂C(0001), Pt clusters tend to form two dimensional planar structures instead of aggregating. The clean Mo₂C(0001) surface interacts with sulfides very strongly and is susceptible to sulfur poisoning. With increasing the coverage of Pt on the Mo₂C surface, the interaction between sulfur and substrate is weakened. The sulfur tolerance ability increases in the order of Mo₂C ≈ Pt₁/Mo₂C < Pt₄/Mo₂C < Pt₈/Mo₂C, where the coverage of Pt on the Mo₂C plays a very effective role. The results provide theoretical guidance for designing Mo₂C based catalysts with high activity and high sulfur resistance.