The H2 Gas Diffusion Electrode Reaction and O2 Gas Diffusion Electrode Reaction are available as subnodes to the corresponding Gas Diffusion Electrode parent nodes.

The equilibrium potential may be defined using the Nernst equation, From material, or by a User defined expression.

The Built in option for the Reference equilibrium potential is based on the reaction stoichiometry and the enthalpies and entropies of the reacting species.

See also Calculation of Built-in Equilibrium and Thermoneutral Potentials and Electrode Reaction in Shared Physics Features in the Current Distribution Interfaces.

Both the exchange current density and the equilibrium potential of an electrode reaction depend on the partial pressures of the reacting species. By the use of a reference state (a given set of partial pressures) and the Reference equilibrium potential and Reference exchange current density, analytical expressions such as the Nernst equation (for the equilibrium potential) and Mass action law or Lumped multistep (for the Butler–Volmer kinetics) may be used to calculate the corresponding partial-pressure dependent values.

Specify the species partial pressures for the reference state used for defining the Reference exchange current density and the Reference equilibrium potential. The default value (1 atm) refers to standard conditions.

If the Reference equilibrium potential is set to Built in, the settings of this section only applies to the Reference exchange current density.

See also Electrode Reaction in Shared Physics Features in the Current Distribution Interfaces.

The Built in option for the Thermoneutral voltage is based on the reaction stoichiometry and the entropies of the reacting species.

See also Calculation of Built-in Equilibrium and Thermoneutral Potentials and Electrode Reaction in Shared Physics Features in the Current Distribution Interfaces.