Adsorption manners of hydrogen on Pt(1 0 0), (1 1 0) and (1 1 1) surfaces at high coverage

Abstract

Density functional theory (DFT) calculations were performed to investigate hydrogen adsorption on Pt(100), (110) and (111) surfaces at different coverages. It is found that each surface has different hydrogen adsorption strength and saturated coverages, and Pt(111) surface has the weakest adsorption as well as smallest saturated coverage. Thermodynamics method was applied to include the effects of temperature and hydrogen partial pressure on the stable hydrogen coverage, where the built phase diagram clearly revealed the reaction condition dependent H concentration on the surface. The theoretically predicted hydrogen desorption temperatures are in nice agreement with available experimental results. Interestingly, the adsorption of hydrogen was also found to be able to modify the morphology of Pt catalyst based on Wulff constructions. All these calculations provide very useful information for reaction mechanism calculations, especially for the hydro-treating reactions, where hydrogen coverage on the surface has very important roles in determining the adsorption configurations of the reactants as well as the final reaction mechanisms.