1 research outputs found
Steric Hindrance of NH<sub>3</sub> Diffusion on Pt(111) by Co-Adsorbed O‑Atoms
A detailed velocity-resolved
kinetics study of NH3 thermal
desorption rates from p(2 × 2) O/Pt(111) is
presented. We find a large reduction in the NH3 desorption
rate due to adsorption of O-atoms on Pt(111). A physical model describing
the interactions between adsorbed NH3 and O-atoms explains
these observations. By fitting the model to the derived desorption
rate constants, we find an NH3 stabilization on p(2 × 2) O/Pt(111) of
0.147–0.014+0.023 eV compared to Pt(111) and a rotational barrier of 0.084–0.022+0.049 eV, which is not present on Pt(111). The model also quantitatively
predicts the steric hindrance of NH3 diffusion on Pt(111)
due to co-adsorbed O-atoms. The derived diffusion barrier of NH3 on p(2 × 2) O/Pt(111) is 1.10–0.13+0.22 eV, which is 0.39–0.14+0.22 eV higher than that on pristine Pt(111).
We find that Perdew Burke Ernzerhof (PBE) and revised Perdew Burke
Ernzerhof (RPBE) exchange–correlation functionals are unable
to reproduce the experimentally observed NH3–O adsorbate–adsorbate
interactions and NH3 binding energies at Pt(111) and p(2 × 2) O/Pt(111), which
indicates the importance of dispersion interactions for both systems