• Girgsdies, Frank
• Schlögl, Robert
• Rabe, Anna
• Behrens, Malte
• Wang, Jihao
• Ortega, Klaus Friedel
• Chen, Shilong
• Rein, Denise
• Doronkin, Dmitry
• Kang, Liqun
• Studt, Felix
• Lunkenbein, Thomas
• Jelic, Jelena
• Debeer, Serena
• Najafishirtari, Sharif
• Grunwaldt, Jan-Dierk
• Schmidt, Franz-Philipp
• Wandzilak, Aleksandra

Abstract

<jats:title>Abstract</jats:title><jats:p>Ammonia is a storage molecule for hydrogen, which can be released by catalytic decomposition. Inexpensive iron catalysts suffer from a low activity due to a too strong iron-nitrogen binding energy compared to more active metals such as ruthenium. Here, we show that this limitation can be overcome by combining iron with cobalt resulting in a Fe-Co bimetallic catalyst. Theoretical calculations confirm a lower metal-nitrogen binding energy for the bimetallic catalyst resulting in higher activity. <jats:italic>Operando</jats:italic> spectroscopy reveals that the role of cobalt in the bimetallic catalyst is to suppress the bulk-nitridation of iron and to stabilize this active state. Such catalysts are obtained from Mg(Fe,Co)<jats:sub>2</jats:sub>O<jats:sub>4</jats:sub> spinel pre-catalysts with variable Fe:Co ratios by facile co-precipitation, calcination and reduction. The resulting Fe-Co/MgO catalysts, characterized by an extraordinary high metal loading reaching 74 wt.%, combine the advantages of a ruthenium-like electronic structure with a bulk catalyst-like microstructure typical for base metal catalysts.</jats:p>

Topics

• impedance spectroscopy
• microstructure
• Nitrogen
• Hydrogen
• precipitation
• cobalt
• iron
• decomposition
• Ruthenium