Influence of Chemical Modifications with Fe, Co, and GDC on the Electrochemical Performance of the Ni-8YSZ Hydrogen Electrode in Solid Oxide Electrolysis Cells

Abstract

Green hydrogen produced via electrolysis using power from renewables is a key contributor to achieving global climate targets in the chemical industry and energy sector. High-temperature electrolyzers based on solid oxide cells (SOC) offer higher electrical efficiency than alternative electrolyzer technologies, but so far, their capital cost and degradation rates are too high for broad commercial deployment. Therefore, research to increase solid oxide electrolysis cell (SOEC) performance and long-term durability is essential for achieving commercial success. This work aims to improve a commercially produced solid oxide cell by modifying the Ni-8YSZ (yttria stabilized zirconia) hydrogen electrode active layer (HEAL) with iron, cobalt, and gadolinia-doped ceria. Feed gas steam concentration and operating temperatures were varied to study the effect of the promoted materials on SOEC performance under different operating conditions. At 700 °C operating temperature, the modifications of Ni-YSZ with Co, Fe, or GDC led to a decrease of electrochemical performance; however, at 800 °C and at steam concentrations higher than 45% significant improvement of performance was observed. The best results were obtained using the SOC modified with Fe and operated at 800 °C in 90% steam concentration, where a current density of −3.7 A cm −2 was achieved at −1.4 V.