We observe comparatively low oxo formation barriers of 17.3 kcal/mol for C and 4.0 kcal/mol for D, indicating relatively facile formation of metal-oxo species for C-H bond activation in methane (Figure ). In contrast, the oxo formation barriers of A and E are considerably higher (i.e., 31.3 kcal/mol and 26.7 kcal/mol, respectively), which is also noteworthy that both activation energies are relatively similarly high even though they were on the opposite ends of the Pareto front in terms of oxo formation energetic favorability (Figure ). Among the four selected codoped SACs, the HAT barrier of ground state C exhibits the lowest HAT barrier energy at 14.7 kcal/mol, followed by D with a moderate barrier of 21.6 kcal/mol. Compared to the C and D systems, E has a higher HAT barrier energy of 39.0 kcal/mol indicating that it requires more energy for HAT and is unlikely to be a proficient catalyst for direct methane-to-methanol conversion. The A SAC has the highest HAT barrier energy at 44.5 kcal/mol, making it the most energetically demanding for the HAT process and unlikely to feasibly catalyze HAT, even when accounting for uncertainty due to error in the DFT functional (Supporting Information Table ). Comparing these energetics, Next, we employed the energetic span model to estimate the catalytic turnover frequency (TOF) of the four selected codoped SACs. We observe that A, C and E share a common TDTS associated with the oxo formation step (Figure , Supporting Information Table ).