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

Abstract

This study evaluates the electrochemical performance of Gd0.1Ce0.9O1.95 (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, Ni0.50Co0.50, Ni0.75Co0.25, 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 (Rp) 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, Ni0.50Co0.50, Ni0.75Co0.25, 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, Ni0.25Cu0.75, and Ni0.50Cu0.50. Increasing Ni percentage within the Ni-Cu alloy structure had a positive impact on the electrochemical performance as cells with Ni0.50Cu0.50 infiltrated cathodes showed relatively close voltage values to those of cells with Ni infiltrated cathodes during short-term galvanostatic tests. Although the SOEC with Ni0.50Cu0.50 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 Ni0.25Cu0.75 infiltrated cathodes when evaluated under 0.20 A·cm−2 for 48 h and at 750 °C.