We present results of first-principle studies for energetics and structural
properties of CO adsorbed on the Pt-Ru surface alloys and on the surface o
f a bulk Pt-Ru alloy. The results showed that the Ru-CO bond strength was i
ncreased from 2.0 to 2.1 eV, whereas the Pt-CO bond was weakened from 1.54
to 1.36 eV after Ru alloying with Pt for the bulk Pt-Ru alloy. On the other
hand, both Ru-CO and Pt-CO bonds are strengthened on the surface alloys.