For the case of the O-H bond activation, we were unable to locate a local minimum using a CH3O radical as the product. Geometry optimization of this hypothesized CH3O radical together with Fe(OH)2 results in formation of CH2O, H2O and Fe(OH), which agrees well with our chemical intuition about the stability of a CH3O radical. The reorganization of the atoms during geometry optimization into CH2O and H2O is therefore not surprising. The energy barrier for 2 TS OH is +62.7 kJ/mol (HSE06; for PBE +118.0 kJ/mol) and the reaction energy ΔE(CH3OH@MO→[CH2O+H2O]@M) is -161.1 kJ/mol (HSE06; -25.9 kJ/mol for PBE). As can be seen from Table , the energy barrier is higher for 2 TS OH than for 2 TS CH .For PBE it is also still slightly lower than for the first C-H energy barrier in methane ( 1 TS CH ), but the HSE06 energy barrier is higher for 2 TS OH than for 1 TS CH . The C-H bond activation can therefore be expected to be the most relevant pathway for methanol oxidation and unwanted overoxidation. Overall, the obtained results for the methanol oxidation step highlight once again the need to prevent methanol overoxidation. The inherently weaker C-H bonds of methanol compared to the C-H bonds of methane make this a necessary design feature of any potential catalyst.