Unveiling the unprecedented catalytic capability of micro-sized Co-ZIF-L for the thermal decomposition of RDX by 2D-structure-induced mechanism reversal.

Abstract

Developing MOF-based catalysts with superior catalytic properties for the thermal decomposition of cyclotrimethylenetrinitramine (RDX) is significant for the application of novel and efficient combustion catalysts oriented to RDX-based propellants with excellent combustion performance. Herein, micro-sized Co-ZIF-L with a star-like morphology (SL-Co-ZIF-L) was found to exhibit unprecedented catalytic capability for the decomposition of RDX, which can lower the decomposition temperature of RDX by 42.9 °C and boost the heat release by 50.8%, superior to that of all the ever-reported MOFs and even ZIF-67, which has similar chemical composition but a much smaller size. In-depth mechanism study from both experimental and theoretical views reveals that the weekly interacted 2D layered structure of SL-Co-ZIF-L could activate the exothermic C-N fission pathway for the decomposition of RDX in the condensed phase, thus reversing the commonly advantageous N-N fission pathway and promoting the decomposition process in the low-temperature stage. Our study reveals the unusually superior catalytic capability of micro-sized MOF catalysts and sheds light on the rational structure design of catalysts used in micromolecule transformation reactions, typically the thermal decomposition of energetic materials.