where the origin (x = 0) is defined at the center of the CL, 𝐿 >W is the CL thickness, 𝐿 dDW is the AEL thickness, and 𝐿 `NW is the anolyte boundary-layer thickness. The thickness of both the catholyte and anolyte boundary layers are assumed to be equal to 25 µm, and are estimated by assuming approximately Fickian behavior of the CO2 at the onset of bubbling (Section S1.6).