Electrochemical behaviors of copper/manganese-doped ceria cermet as a fuel electrode for high-temperature solid oxide cells.

The metal-ceramic composite Cu/Ce0.9Mn0.1O2-δ (Cu/CMO) is investigated as a fuel electrode for solid oxide cells (SOCs) regarding the interconversion between CO and CO2, and exhibits excellent anti-carbon and electrocatalytic performance. When the SOCs are operated in solid oxide fuel cell (SOFC) mode in CO2/CO = 50/50 atmosphere, the maximum power densities of the SOCs are 37, 88, and 151 mW/cm2 at 700, 750, and 800 °C, respectively, indicating that Cu/CMO electrode possesses excellent catalytic activity for CO oxidation. The Cu/CMO is also electrochemically active for CO2 reduction when the SOCs are operated in solid oxide electrolytic cell (SOEC) mode. At an applied voltage of 2.0 V, the current densities of the SOCs are 0.47, 0.87, and 1.36 A/cm2 at 700, 750, and 800 °C, respectively. Short-term durability measurement of CO2 electrolysis at various applied voltages shows that the SOCs is stable with only a small decrease in current density at 1.4 V, while the current density decreases more above 2.0 V, probably due to the deterioration of the electrode at high applied voltages. Long-term stability measurement of the SOCs at an applied voltage of 1.4 V for up to 200 h shows significant stability of the electrode. In this paper, the metal-ceramic composite Cu/CMO is used as a fuel electrode for SOCs and the performance in both SOEC and SOFC modes is investigated. The electrolysis of CO2 and oxidation of CO occurred at the fuel electrode Cu/CMO using CO2/CO = 50/50 mixture as the fuel gas to achieve the mutual conversion of CO2 and CO, respectively. After systematic electrochemical performance tests, SOCs using Cu/CMO as the fuel electrode can be reversibly converted in both SOEC and SOFC modes, achieving efficient conversion between chemical energy and renewable electricity. [ABSTRACT FROM AUTHOR]