Barium carbonate as a synergistic catalyst for the H2O/CO2 reduction reaction at Ni-yttria stabilized zirconia cathodes for solid oxide electrolysis cells

BaCO3 is primarily demonstrated as an excellent synergistic catalyst for efficient electro-reduction of H2O/CO2 to H-2/CO at the state-of-the-art Ni-YSZ (yttria-stabilized zirconia) cathodes for solid oxide electrolysis cells (SOECs) with YSZ electrolytes and strontium doped lanthanum manganite oxygen electrodes. BaCO3 nanoparticles, which are deposited onto porous Ni-YSZ using the infiltration process, can significantly improve the SOEC performance such as increasing the electrode interfacial polarization conductivity over 50% and promoting the electrolysis current density by a factor of up to 2 for the electrolysis of H2O to H-2, CO2 to CO, and co-electrolysis of H2O-CO2 to H-2-CO at 800 degrees C. In addition, it seems that BaCO3 can improve the SOEC durability for the co-electrolysis of H2O-CO2. The improvement is associated with an enhanced surface charge transfer process, which is the rate-determining step for the reduction reaction, as shown by analyzing the AC impedance spectrum measured with a three-electrode configuration. The highest improvement is achieved with CO2 reduction possibly due to the additional enhancement in the adsorption/dissociation process by BaCO3 as revealed with temperature programmed CO2 desorption analysis.