Catalytic decomposition of ammonium perchlorate at BpyNO interfaces: a neural network potential perspective

The catalytic promotion effect of 4,4′-bipyridine 1,1′-dioxide (BpyNO) on the thermal decomposition of ammonium perchlorate (AP) is investigated using combined thermal analysis and neural network potential (NNP)-based molecular dynamics simulations. A small addition of BpyNO (5 wt%) reduces the main decomposition peak of AP by approximately 100 K and increases the total heat release by 2.8-fold (1338 vs. 479 J g⁻¹). The apparent activation energy is significantly lowered from 150.5 to 109.9 kJ mol⁻¹, indicating an accelerated decomposition process. NNP simulations reveal a distinct interfacial decomposition mechanism in the AP/BpyNO system, in which oxygen transfer from ClO₄ to the organic framework dominates the early-stage reactions, in contrast to the proton-transfer-dominated pathway in pure AP. The catalytic interface promotes rapid oxygen migration from ClO₄, hydrogen abstraction, and early disruption of the AP crystal lattice. These synergistic effects result in enhanced reaction kinetics and a fundamentally different decomposition pathway, consistent with comparative simulations against structurally related bipyridine analogues. The findings provide atomic-level insight into organocatalytic regulation of oxidizer decomposition and offer a mechanistic foundation for designing safer and more efficient composite energetic materials.