Breaking the energetic ammonium salts decomposition barrier: atomically dispersed Fe catalysts unveil the pyrolysis mechanisms and oxygen release strategies

The energetic ammonium salts represent a class of oxidizer materials that are extensively utilized in contemporary propellant systems. However, the catalytic pyrolysis mechanisms of these salts remain inadequately explored, hindering the efficient application of new energetic ammonium salts. In this study, taking typical energetic ammonium salts (ammonium perchlorate (AP), ammonium nitrate (AN) and ammonium dinitramide (ADN)) as examples, their pyrolysis on the surface of the prepared Fe single-atom catalysts and the combustion flames of the powders were investigated. We learned that Fe single-atoms can promote the pyrolysis and enhance the flame intensity of ammonium salts. The mechanism of Fe single-atom catalyzed ammonium salts has been investigated through density-functional-theory (DFT) calculations, and the results well explained the experimental phenomena. The AP molecule produces oxygen most readily, primarily through the pyrolysis of *ClO 4 (−3.70 eV). The idea of solving the heat-absorbing decomposition of AN is proposed to catalyze its complete decomposition and to avoid the production of NO. The low decomposition temperature of ADN is due to the five major pyrolysis pathways of the molecule and the presence of self-catalytic intermediates. This paper offers guidelines for comprehending the pyrolysis and combustion mechanisms of energetic ammonium salts.