N-Doped-Induced Local Covalency Elevation for Enhancing Cathodic Performance of Solid Oxide Electrolysis Cells

The Ni-based cathode is central to the performances of solid oxide electrolysis cells (SOECs), yet it suffers from poor oxygen ion conductivity, sluggish electron transport, and inefficient CO 2 /H 2 O activation. This study explores a heteroatom-doping strategy to comprehensively address the ionic, electronic, and molecular issues in solid oxide cells. When operated in SOEC mode, the maximum power density of the N-doped Ni/CGO (NiO/CGON) cathode achieved a 29.6% improvement over its undoped Ni/CGO, along with a 27.3% reduction in polarization resistance. Moreover, a 31.3% increase in maximum current density was obtained along with considerable stable operation over 150 h at an industrial-scale current density of 0.5 A/cm 2 . Combined electrochemical measurements, in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and density functional theory (DFT) simulations reveal that N-doped-induced local covalency elevation via the formation of Ce–O/N bonds substantially promotes the oxygen ion and electron conductivity and creates the synergistic Lewis acid–base sites for simultaneous activation of both CO 2 and H 2 O, thereby collectively addressing the ionic, electronic, and molecular issues in SOCs in one simple method.