Heterogeneous La _0.75 Sr _0.25 Cr _0.5 Mn _0.5 O ₃ ‐Based Nanocomposite Hydrogen Electrode for Efficient and Durable Solid Oxide Cells

Abstract Development of electrocatalytically active, durable hydrogen electrode materials is vital for solid oxide cells (SOCs). La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3 (LSCM) hydrogen electrode shows great potential for durability in a harsh operational environment, although its practical application is critically limited by the low intrinsic electrocatalytic activity. Herein, a heterogeneous LSCM‐Gd 0.1 Ce 0.9 O 1.95 (GDC) nanocomposite hydrogen electrode is synthesized by coupling a self‐assembly synthesis method with a sintering‐free direct assembly technique. The self‐assembly method gives rise to the formation of a nanocomposite with a robust LSCM–GDC heterointerface and increased surface oxygen vacancies. The direct assembly method enables preservation of the original nanostructure and heterointerface in the hydrogen electrode, and the subsequent electrochemical polarization induces in situ construction of a coherent electrode|electrolyte interface. A corresponding electrolyte‐supported single cell achieves a peak power density of 1.04 W cm −2 and an electrolysis current density of 1.51 A cm −2 @1.5 V in pure CO 2 at 850 °C. The cell shows no noticeable degradation during 200 h galvanostatic test in fuel‐cell and electrolysis modes. This work provides an innovative approach for the development of LSCM‐GDC nanocomposite electrodes for efficient and durable SOCs.