Tailored and Improved Protonic Conductivity through Ba(ZxCe10-x)0.08Y0.2O3-δ Ceramics Perovskites Type Oxides for Electrochemical Devices

Abstract: Acceptor-doped barium zirconate cerate electrolytes constitute prospective materials for highly efficient and environmentally friendly electrochemical devices. This manuscript employs a systematic approach to further optimize ionic conductivity in Ba(ZrxCe10-x)0.08Y0.2O3-δ oxides for moderate temperature electrolysis. We found two new composition variants by fixing a cerium/zirconium ratio of 5/4 at the perovskite B-site with incremental zirconium, an observation that contrasts many reports suggesting a linear decrease in conductivity with increasing zirconium. As a result, the composition BaZr0.44Ce0.36Y0.2O3-δ demonstrates a superior ionic conductivity (10.1 mScm-1 at 500°C) to stability trade-off whereas, BaZr0.16Ce0.64Y0.2O3-δ exhibits the highest conductivity (11.5 mScm-1 at 500°C) among the studied pellets. The high protonic conductivity is associated with a high degree of hydration, as confirmed by thermo-gravimetric analysis. In addition, both compositions as electrolytes allow successful hydrogen production in a steam electrolyzer prototype. Electrolysis voltage as low as 1.3 V is attainable at current densities of 600 and 500 mA/cm2 respectively at 600°C, achieving 82% current efficiencies with the later electrolyte