Adsorption of NO on Pt(100) from first principles

Abstract

Density-functional theory has been used to investigate the energetics, structures and electronic properties of NO adsorption on the Pt{100}-(2 × 2) surface. Simultaneous relaxation of the absorbed NO and the top layer of the surface of the metal was performed. We found that with different coverages (θ NO = 0.25, 0.50, 0.75 and 1.00 monolayer), NO adsorbs preferentially in the bridge site. Moreover, NO on the hollow site was unstable and it moves to the bridge site during geometry optimization. The geometric parameters, adsorption energies and the change of the work function were discussed and compared with the experimental and theoretical findings. The interaction between NO and Pt(100) was dominated by an extensive hybridization between the 1π and 2π * MOs of NO and the Ptd x z state for the bridge site.

Mechanistic Study of Nitric Oxide Reduction by Hydrogen on Pt(100) (I): A DFT Analysis of the Reaction Network

“…This additional NO* also prefers to bind to a bridge site, the same as the other two NO* molecules. The differential binding energy of the third NO* is −0.95 eV, which agrees well with the previously reported value of −0.98 eV . At the NO* coverage of 1.00 ML, all four NO adsorbates occupy bridge sites with perpendicular configurations.…”

“…The average binding energy of all four NO adsorbates from our calculation is −1.51 eV, which is close to previously reported values of −1.64 and −1.69 eV, at the same coverage. We note that the NO differential binding energy decreases with increasing coverage, which is in accordance with previous experimental and theoretical , studies of NO adsorption on Pt(100), and DFT studies of NO adsorption on Pt(111) …”

“…Eichler and Hafner reported a BE­(NO) of −2.07 eV using PW91 functional at θ = 0.50 ML on Pt(100), in excellent agreement with our findings. At the same coverage, Moussounda et al reported a differential binding energy of −2.09 eV, similar to our calculated value . The introduction of another NO* into the unit cell further increases the total coverage of NO* to 0.75 ML.…”

“…117 The introduction of another NO* into eV, which is close to previously reported values of −1.64 117 and −1.69 eV, 17 at the same coverage. We note that the NO differential binding energy decreases with increasing coverage, which is in accordance with previous experimental 15 and theoretical 17,117 studies of NO adsorption on Pt(100), and DFT studies of NO adsorption on Pt (111). 118 Using the methodology described in Computational Methods, we construct two phase diagrams to capture the NO adsorption behavior on Pt(100) under typical reaction conditions (e.g., temperature is 400 K, and NO partial pressure is 0.005 atm), as shown in Figure 7.…”

“…Previous studies have shown that surface coverage is a very important parameter in catalytic reactions. At different coverages, surface species exhibit varied adsorption behavior, and elementary steps can have dramatically different energetics. ,,− Therefore, we propose that the surface coverage of NO* should be explicitly accounted for in first-principles studies of NO reduction by H 2 . We have investigated surface coverage effects on the NO reduction by H 2 on Pt(100) reaction mechanism by explicitly including 0.50 ML NO adsorbates in our calculations and determine that the reaction mechanism indeed changes.…”