The reaction free energies of the ORR pathway can be expressed in terms of the adsorption free energies of the intermediates, by computing the differences between them. The free energy of the endpoints was kept fixed. At 0 V (vs SHE) such values are 4.92 eV for the initial state (O2(g)) and 0 eV for the final state (H2O(l)). Precisely, the value of 4.92 eV corresponds to the ORR potential from experiment. Negative values correspond to exergonic processes while positive values are endergonic.