Efficient and Stable Electrochemical Ammonia Synthesis Promoted by in Situ Alloying in Tubular Protonic Ceramic Electrolysis Cells

Abstract Protonic Ceramic Electrolysis Cells (PCECs) enable the in situ production of hydrogen and protons via steam electrolysis, positioning them as promising reactors for environmentally friendly ammonia synthesis. However, the efficiency and stability of this process are currently constrained by the limited catalysis activity and the aggregation of conventional fuel electrodes. Herein, in situ formed Fe‐Co‐Ni alloy nanoparticle catalysts are designed, and find that these alloy sites significantly enhance N 2 adsorption. Selective impregnation of Fe‐Co and Ni exsolution is integrate to promote the in situ formation of Fe‐Co‐Ni alloy catalytic sites within the fuel electrode of tubular PCECs (10 cm 2 active area). Under an applied voltage of 0.6 V, the in situ alloyed PCEC reactor reaches 2.37 × 10 −8 mol s −1 NH 3 synthesis rate at 600 °C, which is 2.1 times that of with common fuel electrode. Density functional theory calculations further reveal that alloying reduces the activation energy for nitrogen hydrogenation, thereby facilitating the reaction pathway. Moreover, the in situ formed alloy sites exhibit a strong anchoring effect, effectively preventing catalyst aggregation at high temperature and enabling stable, efficient ammonia synthesis over 250 h. This study demonstrates the significant potential of in situ alloy catalysts combined with tubular PCECs for electrochemical ammonia synthesis.