The FEM was constructed to simulate the effect of local environment changes on enzymatic HER (DvH [NiFeSe] H2ase) and CO2RR (DvH W-FDH) in the mesoporous electrode, using COMSOL Multiphysics 5.5. Similar models have been applied to follow the concentration of H2 as substrate for H2 oxidation and O2 inhibition in redox hydrogel films or carbon nanotubes, though these models did not consider the concomitant change in local pH or other electrolyte species. The model, and its governing parameters and equations, is described in detail in the Supporting Information, Finite Element Model, and is summarised in Figure .