These two mechanisms are reported to be the primary reaction pathways for the OER. From the energy profiles (Fig. and), it is apparent that the I2M mechanism has a lower energy barrier (4.02 and 3.51 eV, for structures 1 and 2, respectively) for its rate-limiting step (RLS, which is the desorption of O2) and thus is more favorable than the WNA mechanism (7.77 and 7.91