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

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.