Electron-Structure Synergy on La₂Ce₂O₇ for Durable Ammonia-to-Hydrogen Conversion

Ammonia serves as an efficient carbon-free hydrogen carrier with high hydrogen storage density and advanced transportation infrastructure. However, the practical utilization of NH₃-to-H₂ faces significant challenges due to the high cost of noble metal catalysts and the inadequate activity and poor stability of non-noble metal alternatives. Utilizing catalyst supports to modify the structural and electronic properties of active sites offers a promising pathway to overcome these limitations. In this work, La₂Ce₂O₇, a distinct defect-fluorite oxide with mixed electron−proton properties, is introduced as an effective support. Its abundant oxygen vacancies and strong metal−support interaction enable precise spin−orbital synergistic regulation of CoNi alloy active sites. This deeply modulates the CoNi alloy across multiple levels, from electronic structure (spin and orbital ordering) to chemical bonding (spin-polarized M−N bonds) and further to reaction kinetics (concurrent reduction of multiple energy barriers), thereby significantly facilitating N−H bond cleavage. Meanwhile, the cooperative acid−base sites promote NH₃ activation and N₂ desorption, and the H spillover capabilities enhance H migration and H₂ desorption, thus completing the catalytic cycle. The optimized Co₁Ni₂/La₂Ce₂O₇ catalyst achieves a high NH₃-to-H₂ conversion of 97.7% at 550 °C (GHSV = 30,000 mL g_cat⁻¹ h⁻¹) and maintains durable operation for 1000 h, demonstrating its strong potential. Lastly, the operating temperature window aligns well with that of solid oxide fuel cells, enabling direct utilization of produced H₂ for efficient on-site electricity generation.