Pr and Ti co-doped Strontium Ferrite as a Novel Hydrogen Electrode for Solid Oxide Electrolysis Cell

• Pr and Ti co-doped Strontium Ferrite is successfully used as hydrogen electrode of SOEC.
• A unit cell with PSTF hydrogen electrode exhibits excellent electrochemical performance for steam electrolysis.
• Mass transport is the main rate-limiting step of PSTF electrode for steam electrolysis.

Pr and Ti co-doped strontium ferrite oxide Pr0.3Sr0.7Ti0.3Fe0.7O3−δ (PSTF) has been examined as a hydrogen electrode for solid oxide electrolysis cell (SOEC). X-ray diffraction analysis shows that the PSTF material maintains phase stability during 20 hours of treatment under 5%H2/N2 conditions. An SOEC with a configuration of PSTF||SDC|YSZ||LSM-YSZ operates under various H2O concentrations and current densities. As can be observed from the AC impendence spectra of the PSTF electrode, H2O/H2 adsorption desorption or surface diffusion process is the main rate-limiting step for steam electrolysis reaction. The low-frequency arc RL obviously depends on the H2O concentration and the electrolysis current density. Steam starvation in hydrogen electrode occurs at low H2O concentration and large current density. A maximum current density of 302 mA cm−2 is obtained at an electrolysis voltage of 1.46 V in Ar/H2/60%H2O at 800 °C. The corresponding polarization resistance of PSTF electrode is as small as 0.25 Ω cm2. This study demonstrates that Pr0.3Sr0.7Ti0.3Fe0.7O3−δ is a promising hydrogen electrode material of SOEC for H2O electrolysis.