In-situ Zr-doped nanostructured FeCo2O4 spinel unsupported catalyst for hydrogen production from ammonia decomposition

Ammonia decomposition represents a sustainable pathway for on-demand hydrogen production, yet conventional Fe–Co-based catalysts suffer from thermal sintering and insufficient activity at moderate temperatures. Herein, we report a novel strategy for engineering Zr-doped FeCo₂O₄ spinel catalysts with low crystallinity via a scalable sol-gel method. The optimized FeCo₂O₄–Zr_0.02-550 catalyst achieved nearly 100 % NH₃ conversion at 525 °C under GHSV of 3,000 mL·g-1 cat·h⁻¹. Comprehensive characterization revealed that Zr doping induced multiple synergistic effects: (1) Formation of stable Zr–O–Fe/Co interfacial structures suppressed active site aggregation, maintaining 95 % activity after 80 h of continuous operation; (2) Oxygen vacancy generation and cation valence modulation accelerated N₂ desorption and electron transfer kinetics; (3) Enhanced surface acidity and reducibility improved NH₃ adsorption and H₂ desorption efficiency. This catalyst demonstrates a cost-effective production process and industrial scalability.