CO adsorption on Pt (1Â 1Â 1) and Pd (1Â 1Â 1) surfaces: A first-principles based lattice gas Monte-Carlo study

►We model CO lateral interaction on Pt and Pd surfaces. ► Parameterized lattice gas model based on DFT calculations. ► CO adsorption is stronger on Pd (1 1 1) at low coverage. ► Lateral interactions drive a faster decrease of binding on Pd (1 1 1).