Synthesis of Cu-ATRZ@Al/APTES Surface-Loaded Composite Particles and Investigation of Their Catalytic Performance in the Thermal Decomposition of Ammonium Perchlorate

The molecular bridge-mediated discontinuous loading strategy preserves active aluminum. • 5 wt% composite drops AP decomposition peak by 116.9°C and boosts heat release by 75.8%. • Cu 2+ /Cu + redox, ligand exotherm, and hierarchical loading synergize AP kinetics. • Interface engineering balances catalytic activity and reactivity. The dense native Al 2 O 3 layer on the surface of aluminum powder hinders interfacial contact with the decomposition products of ammonium perchlorate (AP), thereby restricting the energy release efficiency of Al/AP systems. To address the issue that conventional MOF coating strategies often achieve catalytic loading at the expense of active aluminum content, this work proposes an organosilane molecular-bridge-mediated surface-loading strategy: An amino-terminated self-assembled functional layer is fabricated on aluminum powder with 3-aminopropyltriethoxysilane (APTES). Aluminum particles are discretely anchored onto energetic MOF crystal surfaces through hydrogen bonding between amino groups and Cu-ATRZ ligands, as well as weak coordination with unsaturated Cu sites, yielding surface-loaded Cu-ATRZ@Al/APTES composite particles. This strategy avoids excessive shielding of active aluminum by a continuous coating layer, preserving an active aluminum content of 86.2% while achieving intimate particle-scale contact between catalytic sites and the fuel phase. Catalytic tests on AP thermal decomposition demonstrate that with only 5 wt.% addition of the composite particles, the peak temperature of AP high-temperature decomposition dropped significantly from 436.0°C to 319.1°C, a decrease of 116.9°C, whilst the exothermic heat of the system increased from 550.7 J∙g −1 to 968.2 J∙g −1 . Non-isothermal kinetic analysis reveals that the apparent activation energy of the composite system decreases from 196.7 kJ·mol −1 for pure AP to 156.5 kJ·mol −1 , and the catalytic effect is markedly superior to that of a physically mixed system. Mechanistic analysis indicates that the catalytic enhancement of this composite architecture stems from a triple synergistic effect: (i) electron transfer pathways enabled by the reversible Cu 2+ /Cu + valence interconversion, (ii) localized thermal feedback from the exothermic decomposition of the energetic ligand framework, and (iii) a shortened mass-transport distance for oxidizing species diffusing toward the fuel phase resulting from the surface-loaded structure. This work provides an interfacial engineering concept for energetic MOF/metal fuel composite systems that balances catalytic activity with fuel reactivity. Download: Download high-res image (191KB) Download: Download full-size image