Atmosphere dependence of anode reaction of intermediate temperature steam electrolysis using perovskite type proton conductor

The effect of oxygen partial pressure on anode reaction of steam electrolysis using SrZr_0.5Ce_0.4Y_0.1O_3-α (SZCY-541) proton conducting electrolyte was investigated by AC impedance measurement in this work. The anode reaction was enhanced by increasing oxygen partial pressure, and this result was opposite to the expectation from the conventional anode reaction (water splitting reaction). The increase in the electrode reaction conductivity with oxygen chemical potential was proportional to ^PO21/4$$ {P_{{\mathrm{O}}_2}}^{1/4} $$ at 600 °C and at higher oxygen partial pressure region of 700 and 800 °C, suggesting the possibility that the enhancement is caused by the increase in hole concentration on the electrolyte surface near the anode.