A General Stepwise Confinement Strategy for Rapidly In Situ Precipitated Nanocatalysts within N‐Doped Hollow Carbon Spheres Toward Efficient Thermal Decomposition of Ammonium Perchlorate

Abstract Nanoconfined composites exhibit outstanding catalytic performance for the thermal decomposition of ammonium perchlorate (AP). However, it remains a formidable challenge to construct nanoconfined catalysts when the restricted species are insoluble precipitates that form rapidly at room temperature. Herein, a general precursor‐based stepwise confined strategy is proposed to encapsulate M 3 [Fe(CN) 6 ] 2 ·xH 2 O (M‐Fe‐PBA) (M = Fe, Co, Ni, Cu, Zn) within N‐doped hollow carbon nanospheres (NHCs), resulting in yolk‐shell structured composites, M‐Fe‐PBA@NHCs. Catalytic tests reveal that 5 wt.% Co‐Fe‐PBA@NHCs show the highest catalytic activity among the M‐Fe‐PBA@NHCs composites, significantly lowering the high‐temperature decomposition peak of AP and increasing its heat release. Electrochemical analysis confirms that fast electron transfer of Co‐Fe‐PBA@NHCs facilitates AP combustion. TGA‐FTIR‐MS measurements further elucidate an accelerated decomposition pathway. Density functional theory calculations indicate that NH 3 and O 2 released during AP degradation are preferentially adsorbed on the in situ formed Co 3 O 4 /CoFe 2 O 4 , promoting O 2 reduction to O 2 − species and facilitating the deeper oxidation of NH 3 into higher‐valence NO 2 . Crucially, this confinement strategy enables the efficient incorporation of instantly formed insoluble species into any hollow host material with accessible voids, providing a versatile platform for the development of multifunctional nanoconfined catalysts and the rational design of high‐performance confined catalysts with potential applications.