The vibrational and thermodynamic properties of hydrogen adsorbed on the Pt(100) surface: a theoretical study

Abstract

Abstract The adsorption of hydrogen on the Pt(100) surface is investigated theoretically within the conventional ultrahigh vacuum (UHV) surface modeling. Both density functional theory (DFT) and Monte Carlo (MC) simulation are implemented to determine the stability, the vibrational properties of the adsorbed hydrogen atom, and the H-H pair interactions. From the converged data, it is found that the H adsorbed on the bridge sites (B sites) have the strongest binding energy. Meanwhile, the H adsorbed on the top sites (T sites) have the highest vertical stretching frequency. In the increment of H coverage ( Θ H ), up to 1 ML, only the H on the B sites are counted. The shape of the g-value curve obtained by MC simulation shows a good agreement with the result of the cyclic voltammetry (CV) measurement. Reducing the pair interaction parameters by about 30%, the g-value is also decreased. From 0.3 to 0.6 with respect to Θ H , the g-value is extremely fitted to the experimental data. This indicates that the interactions of H-H on the Pt(100) surface within the range of 0.3 < Θ H < 0.6 are mainly attributed to those hydrogen atoms adsorbed on the B sites.