Electron-Structure Synergy on La ₂ Ce ₂ O ₇ 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 gcat−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.