Figure shows the different steps of the adsorbate evolution mechanism (AEM) proposed for water oxidation and the equations necessary to calculate each step of the mechanism. According to the computational hydrogen electrode model proposed by Nørskov and coworkers, steps 1 and 2 are typically the potential limiting steps of the AEM mechanism of OER . Therefore, in order to calculate the theoretical overpotential, ΔG1 and ΔG2 must be calculated based on the binding energies of the intermediates calculated in the previous section. 1.23eV shall then be subtracted from the larger of the two energies in order to calculate the theoretical overpotential .