Optimizing H2 production via NH3 decomposition: Alkali metal-doped Fe-based catalysts with FexN active phases

Ammonia (NH 3 ) decomposition is a practical approach to overcome the challenges associated with hydrogen storage and transportation. The choice of catalyst and understanding the catalytic mechanism are key factors in optimizing H 2 production by NH 3 decomposition performance. In this work, a series of alkali metal-doped Fe-based catalysts were synthesized via a solvothermal method, and the formation of Fe x N active phases was systematically investigated. The Fe-based catalysts were pretreated under different atmospheres (H 2 , NH 3 , and N 2 ), followed by comprehensive characterization using BET, XRD, SEM, NH 3 -TPD, XPS, and other techniques. The optimized catalytic activity for NH 3 decomposition was attributed to the formation of Fe x N active phases, and the formation pathway of Fe x N active phases and their catalytic promotion mechanism were further elucidated through XRD, NH 3 -TPD-MS, and XPS analyses. Significantly, catalysts treated with pure NH 3 exhibited an increase in the electron density of Fe species and a decrease in the apparent activation energy. The incorporation of alkali metal doping further amplified this effect, ultimately leading to enhanced hydrogen production performance from NH 3 decomposition. This work underscores the critical function of the Fe x N active phase in facilitating efficient NH 3 decomposition for hydrogen generation, offering invaluable insights into the development of sophisticated alkali metal-doped Fe-based catalysts.