No abstract

No abstract

Supports can widely affect or even dominate the catalytic activity and selectivity of nanoparticles because atomic geometry and electronic structures of active sites can be regulated, especially at the interface of nanoparticles and supports. However, the underlying mechanisms of most systems are still not fully understood yet. Herein, we construct the interface of Co3O4/TiO2 to boost ammonium perchlorate (AP) catalytic decomposition. This catalyst shows enhanced catalytic performance. With the addition of 2 wt % Co3O4/TiO2 catalysts, AP decomposition peak temperature decreases from 435.7 to 295.0 °C and activation energy decreases from 211.5 to 137.7 kJ mol–1. By combining experimental and theoretical studies, we find that Co3O4 nanoparticles can be strongly anchored onto TiO2 supports accompanied by charge transfer. Moreover, at the interfaces in the Co3O4/TiO2 nanostructure, NH3 adsorption can be enhanced through hydrogen bonds. Our research studies provide new insights into the promotion effects of the nanoparticle/support system on the AP decomposition process and inspire the design of efficient catalysts.

Energetic additives can effectively increase the heat release of ammonium perchlorate (AP) decomposition to prevent nonenergetic additives from decreasing the energy density of composite solid propellants. However, the roles of energetic additives are unclear due to their complex changes in the decomposition process. Using ZIF-67 as a model energetic additive, we investigate its roles and catalytic processes in the decomposition of AP, especially the effect on heat release. We find that the decomposition process includes two periods: low-temperature oxidation of ZIF-67 by AP and high-temperature catalytic decomposition of excess AP. The oxidation of ZIF-67 can release a mass of heat and provide oxidation products for catalytic decomposition of excess AP. Meanwhile, the heat release of excess AP is increased to 2.33 times compared with pure AP (1.83 vs 0.78 kJ•g −1 ), and the relationship between heat release and the content of ZIF-67 is quantified. Our results provide new insights into the roles of MOFs in enhancing the thermal decomposition of AP.

No abstract