Efficient intermediate-temperature steam electrolysis with Y : SrZrO3–SrCeO3 and Y : BaZrO3–BaCeO3 proton conducting perovskites†
Ceramic proton conductors have the potential to become important components in future clean and efficient energy technologies. In this manuscript, barium cerium yttrium zirconate (Ba(Zr0.5Ce0.4)8/9Y0.2O2.9) and strontium cerium yttrium zirconate (SrZr0.5Ce0.4Y0.1O2.95), proton conducting perovskites were employed as solid oxide electrolysis cell (SOEC) electrolytes for hydrogen production via intermediate temperature steam electrolysis at 550 and 600 °C. Cathode-supported button cells examined for a 12 μm Ba(Zr0.5Ce0.4)8/9Y0.2O2.9 electrolyte, with Ni–SrZr0.5Ce0.4Y0.1O2.95 as the H2-electrode, and porous Ba0.5La0.5CoO3 as the anode reached current densities of 0.2 and 0.5 A cm−2 with applied voltage of 1.45 V, at 550 and 600 °C, respectively. Moreover, a hydrogen evolution rate of 127 μmol cm−2 per minute was achieved at 0.5 A cm−2, translating to a current efficiency of 82%. In addition, excellent cell performance was obtained using SrZr0.5Ce0.4Y0.1O2.95 as an electrolyte. Current densities of 0.2 and 0.5 A cm−2 were obtained at 600 °C with applied voltages of 1.28 and 1.63 V, achieving faradaic current efficiencies of 88 and 85%. The NiO–SrZr0.5Ce0.4Y0.1O3−δ composite cathode was more favorable for the densification of the supported Ba(Zr0.5Ce0.4)8/9Y0.2O2.9 electrolyte during sintering and could be promising for use as a cathode substrate in proton-conducting SOECs.