CO Adsorption on (110)-(1 × 2) Missing-Row Reconstructed Surfaces of Pd, Au, and Pd3Au: Electronic Structures and Vibrational Frequencies

The adsorption of CO molecule on (110)-(1 × 2) missing-row reconstructed surfaces of Pd, Au, and Pd3Au with 87.5% Au segregation in the topmost layers were investigated by first-principles calculations based on density functional theory. On a pure Pd surface, CO is preferencially adsorbed on pseudo-fcc hollow site near the ridge sites. On pure Au and alloy surfaces, generally the ridge sites are the most stable for adsorption. The charge accumulation between the C atom and the surface atoms explains the calculated adsorption energies, with higher charge accumulation yielding a higher binding energy. The interaction of CO with the surfaces and the adsorption energies were also analyzed using the crystal orbital overlap population (COOP) technique and by considering the d-band model. CO vibrational modes were experimentally investigated for comparison. The vibrational frequencies are strongly influenced by the number of nearest neighbors of surface atoms as well as the type of atoms that constitute the near...