Catalytic ignition of N(CN)2− ionic liquid-H2O2 with zero-dimensional Cu-MOFs

Abstract

Ionic liquid-H₂O₂ is one of the most important proposed systems for green propellants. However, due to its weak oxidizing ability, H₂O₂ can hardly ignite ionic liquids. Therefore, in this work, four potential low-dimensional metal–organic frameworks (Cu-MOFs 1–4) were first synthesized for the ignition of a N(CN)₂⁻ ionic liquid-H₂O₂ system. The results show that zero-dimensional Cu-MOFs 3–4 could catalyze N(CN)₂⁻ ionic liquid-H₂O₂ from non-ignition to combustion, with an ignition delay time of 30 ms by using Cu-MOF 3–4. Through DMPO-probed EPR tests and DFT calculations, the catalytic mechanism was proposed and it was suggested that H₂O₂ releases the strong oxidizing ·OH and ·OOH and then electrons are transferred to the ionic liquid by a free radical chain reaction. This work paves the way for the development and applications of ionic liquid-H₂O₂ as a hypergolic bipropellant.