Carbon dioxide reduction in solid oxide electrolyzer cells utilizing nickel bimetallic alloys infiltrated into Gd0.1Ce0.9O1.95 (GDC10) scaffolds

This study evaluates the electrochemical performance of Gd_0.1Ce_0.9O_1.95 (GDC10) cathodes infiltrated with bimetallic Ni-Co and Ni-Cu alloy electrocatalysts for CO₂ electroreduction in solid oxide electrolyzer cells (SOECs). The electrochemical reduction performance of SOECs with cathodes infiltrated with Ni-Co and Ni-Cu alloys was compared to the performance of SOECs having cathodes infiltrated with Ni, Co, and Cu. Electrochemical performance was evaluated at 750, 800, and 850 °C. Cells with Co, Ni_0.50Co_0.50, Ni_0.75Co_0.25, and Ni infiltrated cathodes displayed relatively similar CO₂ electroreduction performance; however, SOECs having Co infiltrated cathodes had slightly better catalytic performance towards CO₂ reduction as demonstrated by their lower polarization resistance (R_p) values of 8.54, 4.03, and 1.25 Ω·cm² when measured under open circuit voltage (OCV) at 750, 800, and 850 °C, respectively. Cells having Co, Ni_0.50Co_0.50, Ni_0.75Co_0.25, and Ni infiltrated cathodes showed a stable long-term CO₂ electroreduction performance with Faradaic efficiency values approaching 100 % when tested under 0.20 A·cm^–2 for 48 h and at 750 °C. Results indicate that SOECs with Ni infiltrated cathodes possessed better short- and long-term CO₂ electroreduction performance compared to SOECs featuring cathodes infiltrated with Cu, Ni_0.25Cu_0.75, and Ni_0.50Cu_0.50. Increasing Ni percentage within the Ni-Cu alloy structure had a positive impact on the electrochemical performance as cells with Ni_0.50Cu_0.50 infiltrated cathodes showed relatively close voltage values to those of cells with Ni infiltrated cathodes during short-term galvanostatic tests. Although the SOEC with Ni_0.50Cu_0.50 infiltrated cathode experienced performance degradation throughout the long-term test period, it demonstrated better electroreduction performance having Faradaic efficiency values approaching 100 % compared to cells with Cu and Ni_0.25Cu_0.75 infiltrated cathodes when evaluated under 0.20 A·cm^–2 for 48 h and at 750 °C.