Improve energy release of boron by tunable metal-organic frameworks via synergetic micro-explosion and catalysis

Boron is considered as one of the most promising high energy additives to improve the energy density of aerospace propellants and energetic materials. However, the low energy release properties restrict its practical applications. Herein, three kinds of boron-based composite energetic particles (nB@MOF) were prepared by encapsulating nano boron (nB) in metal-organic frameworks (MOFs) by a self-assembly method with Zn, Co and Mo as metal nodes, and 2-methylimidazole and ethylenediamine as organic ligands. The characterization and dynamics results show that the combustion of organic ligands can induce micro-explosion to destroy the surface oxidation layer of agglomeration and promote the oxidation efficiency of boron. Furthermore, the metal oxide catalyst generated in-situ on nB surface by metal nodes can reduce the initial oxidation temperature and improve the mass transfer distance and interface contact of the oxidation reaction. Compared with nB, the maximum pressurization rate of nB@MOF with 2-methylimidazole as the organic ligand is increased by 31.1 times, the initial oxidation temperature of nB@MOF with Mo as the metal node is reduced by 185.9°C, and the combustion heat of all nB@MOF are increased by more than 1.2 times. This work demonstrates that the energy release properties of boron can be effectively improved by synergistic effect of micro-explosion process and interfacial catalysis.