where ΔE is the adsorption energy (likewise, binding energy) of the intermediate, ΔZPE is the zeropoint energy change and ΔS is the entropy change, respectively. ZPEs and Entropies of gas species at standard conditions were taken from the international tables, and the entropy of solidstate species was considered equal to zero. The ZPE and entropy corrections of adsorbed molecules were computed with a vibrational analysis within the harmonic approximation.