Stepwise fabrication of a highly efficient core-shell Co3O4@NHCs catalyst for thermal decomposition of ammonium perchlorate

Nano-sized Co 3 O 4 was stepwise confined into N-doped hollow carbon nanospheres. • Yolk-shell Co 3 O 4 @NHCs exhibits the best catalytic activity for AP pyrolysis. • In situ formed Co 3 O 4 -graphene composite accelerates the deep oxidation of ammonia. • A possible catalytic mechanism for AP combustion was systematically proposed. Transition metal oxides are widely used to catalyze the decomposition of ammonium perchlorate (AP) because of their reversible multivalent redox behavior. However, their catalytic performance is often constrained by particle aggregation and insufficient exposure of active sites. We encapsulate the precursors within nitrogen-rich hollow carbon nanospheres (NHCs) to synthesize core–shell MCo 2 O 4 @NHCs (M = Fe, Co, Ni, Cu, Zn, V, Cr, Mn) composites via our previously reported stepwise confined strategy. Among these, 5 wt% Co 3 O 4 @NHCs + AP exhibits the best catalytic activity, lowering the high-temperature decomposition peak of AP by 151 °C and increasing heat release by 2.13 times compared to pure AP. Kinetic analysis shows that Co 3 O 4 @NHCs significantly reduces the activation energy under the A2 model. Electrochemical tests confirm its superior electron-transfer capability, which facilitates AP decomposition. TG-FTIR-MS/GC reveals that Co 3 O 4 @NHCs accelerates NH 3 oxidation. DFT calculations indicate that the Co 3 O 4 @NHCs surface exhibits the strongest adsorption for both NH 3 and O 2 , promoting NH 3 oxidation by surface active oxygen species to generate NO x . Based on these results, a rational catalytic pathway for AP decomposition is proposed. This work validates the “spatial confinement + interface regulation” strategy and offers new insights into the design of efficient burning rate catalysts. Download: Download high-res image (173KB) Download: Download full-size image