The metals provided with CARE include 8 face-centered cubic (fcc), 1 body-centered cubic (bcc), and 5 hexagonal close-packed (hcp) structures on the three most stable hkl surface facets for each one, (Supplementary Fig. ). Metal surfaces were modeled by four to ten layer slabs (Supplementary Table ), where the half uppermost layers were fully relaxed and the bottom ones were fixed to the bulk distances. A surface coverage concentration of 0.02 molecules • Å -2 was defined for all the adsorption structures, a reasonable value to neglect lateral interactions. The vacuum between the slabs was set between 13 and 16 Å and the dipole correction was applied in z direction . The Brillouin zone was sampled by a Γ-centered 3 × 3 × 1 k-points mesh generated through the Monkhorst-Pack method . Transition states were obtained with the improved dimer method .