First-principles theory and microcalorimetry of CO adsorption on the {2 1 1} surfaces of Pt and Ni

Chemisorption of CO on the stepped Pt{2 1 1} and Ni{2 1 1} surfaces is studied within first-principles density functional theory (DFT) and by microcalorimetry experiments. Adsorption initially occurs on step atoms and proceeds on terraces at higher coverages for both surfaces. CO adsorption on Pt{2 1 1} is found to be stronger than adsorption on Ni{2 1 1} at every CO coverage. Although DFT overestimates the heat of adsorption of CO on both surfaces in comparison with experimentally obtained values, the difference between CO adsorption on the two surfaces is in excellent agreement with experiments. Conversely to the case of Pt surfaces, little variation of the initial adsorption energy of CO between low Miller index Ni surfaces and the Ni{2 1 1} surface is found from both DFT calculations and microcalorimetry experiments.