Rational design of Sr₂Fe_1.5Mo_0.4Y_0.1O_6-δ oxygen electrode with triple conduction for hydrogen production in protonic ceramic electrolysis cell

Protonic ceramic electrolysis cells (PCECs) are emerging as potential technology to achieve efficient electrochemical hydrogen production and purification due to their high conversion efficiency and low cost. However, their maturity on a large-scale hydrogen production is notoriously hindered by the poor activity and stability of oxygen electrodes. In this work, a Sr₂Fe_1.5Mo_0.4Y_0.1O_6-δ (SFMY) oxygen electrode was designed, which shows a stable phase structure, enhanced hydration capacity, and special triple conduction (H⁺/O²⁻/e⁻). Electrical conductivity relaxation measurement demonstrated that SFMY showed faster H₂O surface exchange process and improved bulk ion mobility. The as-fabricated PCEC using SFMY as the oxygen electrode can achieve a current density as high as 1570, 1235, 827, and 516 mA·cm⁻² at 750 °C, 700 °C, 650 °C, and 600 °C, respectively, at a voltage of 1.3 V while displaying excellent operation stability at 700 °C during the test period of about 240 h. These results suggest that SFMY can be a potential oxygen electrode for PCECs.