Engineering High‐Performance Hypergolic Propellant by Synergistic Contribution of Metal–Organic Framework Shell and Aluminum Core

Abstract

Hypergolicity is a highly desired characteristic for hybrid rocket engine‐based fuels because it eliminates the need for a separate ignition system. Introducing hypergolic additives into conventional fuels through physical mixing is a feasible approach, but achieving highly reliable hypergolic ignition and energy release remains a major challenge. Here, the construction of core–shell Al@metal organic framework (MOF) heterostructures is reported as high‐performance solid hypergolic propellants. Upon contact with the liquid oxidizer the uniformly distributed hypergolic MOF (Ag‐MOF) shell can induce the ignition of hypergolic‐inert fuel Al, resulting in Al combustion. Such a synthetic strategy is demonstrated to be favorable in hotspot generation and heat transfer relative to a simple physical mixture of Al/Ag‐MOF, thus producing shorter ignition delay times and more efficient combustion. Thermal reactivity study indicated that the functionalization of the Ag‐MOF shell changes the energy release process of the inner Al, which is accompanied by a thermite reaction. The synergistic effect of implantation of hypergolic MOF and high energy Al contributes to high specific impulses of 230–270 s over a wide range of oxidizer‐to‐fuel ratios.