Fabrication of highly catalytic active α-Fe2O3-carbon nanotube composites for thermal decomposition of ammonium perchlorate by light and temperature control strategy

For alleviating agglomeration of α-Fe2O3 nanoparticles and improving their catalytic activities as burning rate catalysts (BRCs) in solid propellants, Fe(CO)5 as the iron source was encapsulated into the inner space and/or loaded onto the outer surface of carbon nanotubes (CNTs) via ultrasonication with visible light and temperature control strategy. The Fe(CO)5-CNTs composites were subsequently transformed into α-Fe2O3-CNTs nanocomposites by Fe(CO)5 pyrolysis. The as-synthesized α-Fe2O3-CNTs composites were utterly characterized by HRTEM, SEM, BET, XPS, FTIR, Raman, and XRD. The catalytic combustion results show that the nanocomposites are highly active in boosting the thermal degradation of ammonium perchlorate (AP). α-Fe2O3&CNTs(S1) nanocomposite, the most excellent one, shifts left the peak temperature of the high-temperature decomposition (HTD) region of AP by 103.7 °C and increases its release heat by 190 %. Moreover, a carbon nanotube with a smaller outer diameter and higher iron content is conducive to enhancing AP thermal deterioration. A possible mechanism of AP decomposition with the addition of the nanocomposites was investigated by thermal decomposition dynamics, in-situ solid-state FTIR, and gas phase FTIR-MS technique. The mechanistic research implies that the produced NH3 and HClO4 gases can be absorbed on the nanocomposite surfaces to form more superoxide anions (O2−) during AP decomposition, accelerating the generation of NO from N2O and facilitating AP disintegration at a lower temperature. A tentative AP decomposition mechanism in the presence of the α-Fe2O3-CNTs nanocomposites is therefore proposed.