For ORR on Pt(111), these two steps are not really independent of each other, as demonstrated by AIMD based thermodynamic integration and metadynamics (MTD) simulations. The barrier The calculated free energy barrier is averaged to about 0.48 eV (Table ), in line with recently estimated value of 0.68 eV, but significantly lower than the earlier estimate of 2.06 eV without considering the solvation effects of H2O. At the potential of zero charge, the associative channel is clearly favored on Au(100), due to its lower activation barrier, and the 2e the CV, and q being the extra charged added to the slab. More details are provided in the Supporting Information (Figure and S2; Table and).