Due to the pronounced difference in complexa�on constants, only Fe 3+ ca�ons are expected to precipitate. If Fe 2+ ca�ons are dissolved in water, they will anyway thermodynamically be oxidized into Fe 3+ ca�ons by O 2 . (iv) Based on the GDE ICP-MS data at 20 °C that will be discussed later, the rate of produc�on of dissolved Fe ions is assumed to be approximately two �mes faster in O 2 than in Ar GDE experiments. (v) A homogeneous poten�al distribu�on is assumed in the catalyst layer.