Ab initio study of alloying and straining effects on CO interaction with Pt

We present the systematic picture of alloying and straining effects on the Pt-CO interaction via ab initio density functional calculations. The results show that alloying neighbors (Ru, Sn, and Mo) and/or compressive strain increase the valence electron populations of the Pt atoms in the first layers of the modified Pt surfaces. The larger valence electron population of the Pt atom tends to prevent CO from donating electrons in the adsorption reaction, resulting in the weak Pt-CO bond. We suggest that the degree of the donation from CO determines the Pt-CO bond strength.