Fig. 6: The representation of partial conductivity of an oxygen-ion, a proton, and an electron hole as a function of partial water pressure at various SOEC operating conditions.
From: Enhancing the Faradaic efficiency of solid oxide electrolysis cells: progress and perspective

a At 800oC and pO2 = 0.2 atm; b at 800oC and pO2 = 10-5 atm; c at 600oC and pO2 = 0.2 atm; d at 600oC and pO2 = 10-5 atm. [Reprinted figure with permission from ref. 49. Copyright (2017) Elsevier].