Long-term stability of Ce-Cu modified Ni-8YSZ electrodes under both fuel cell and co-electrolysis operation

Solid oxide cells (SOCs) can operate reversibly as both fuel cells and electrolysers using fuels such as biogas and hydrogen, but long-term durability remains a major challenge for conventional Ni-8YSZ electrodes. Two Ce-Cu loading levels were investigated across fuel-cell and co-electrolysis operation, with a combined electrochemical testing duration exceeding 2000 h. In fuel cell mode with simulated biogas, high-load Ce-Cu cells achieved a peak power density of 0.40 W cm −2 at 750°C, compared with 0.19 W cm −2 for the unmodified cell, whilst Raman spectroscopy confirmed near-complete suppression of graphitic carbon. During wet-CO 2 co-electrolysis, low-load Ce-Cu cells operated for over 1050 h versus approximately 400 h for the benchmark. XRD identified metallic Cu and indicated Ce incorporation into a zirconate-type solid solution, and post-mortem SEM-EDX showed an intact electrode-electrolyte interface, with Ni particle coarsening observed in the post-mortem electrode after prolonged co-electrolysis.