Accelerated thermal decomposition of ammonium perchlorate by electron transfer from dinuclear rare-earth EMOFs

Abstract

Energetic metal-organic framework materials (EMOFs) are a class of energetic complexes formed by constructing energetic organic compounds with metal ions, which have garnered considerable attention due to their potential catalytic role in promoting the thermal decomposition of ammonium perchlorate (AP). However, how to improve the catalytic effect is still long-standing issue for EMOFs. Based on the electron transfer between rare earth metal ions with positive holes in the d, f-orbital and ammonium perchlorate ions, three rare earth EMOFs (La2(tza)3(H2O)6·4H2O, Ce2(tza)3(H2O)6·3H2O, and Nd2(tza)3(H2O)6·4H2O) were synthesized by solution evaporation method and their effects on the thermal decomposition of AP were investigated. The three EMOFs are binuclear isomorphic and form thermally stable (Tdet > 630.0 K) 3D structures through extensive hydrogen bonds. In addition, the introduction of lanthanide metals can enhance the electron transfer ability of EMOFs and promote the electron transfer of AP/EMOFs mixtures, which is beneficial to modulate the catalytic performance of EMOFs for the AP thermal decomposition. The addition of the three EMOFs caused the high-temperature decomposition peak of AP towards the low-temperature. Meanwhile, the temperature of the high-temperature decomposition peak was advanced by 46.8 K ∼ 59.8 K, and the activation energy (Ea) was reduced by 85.02 ∼ 117.71 kJ/mol, which could significantly improve the thermal decomposition performance of AP. Most importantly, compared to the other two EMOFs, the cation in Nd2(tza)3(H2O)6·4H2O has the highest effective nuclear charge number in the f orbital and strongest electron transfer ability, which can reduce the Ea of AP to 96.85 kJ/mol. Overall, the strategy of construction EMOFs by increase the electron transfer ability can provide guidance for the exploration of novel and efficient energetic catalysts.