Ferrocene-modified azole-borane complexes achieve efficient hypergolic ignition with hydrogen peroxide via dual-pathway mechanism

Abstract

The safety of hydrogen peroxide (e.g. 90% H₂O₂) is intrinsically linked to its concentration. Thus it's of great significance to explore the self-ignition property of low-concentration H₂O₂. Nevertheless, most of current fuels remained constrained by their inherent reactivity limitations, failing to initiate hypergolic ignition with 70% H₂O₂. In this work, we developed an "all-in-one" design strategy integrating ferrocene's catalytic functionality with imidazole/triazole-borane hypergolicity, synthesizing novel high-activity complexes (Fc 4-7). All complexes demonstrated hypergolic reactivity with 70% H₂O₂.Especially, Fc-6 exhibited the shortest ignition delay time (46 ms). To further optimize hypergolicity performance, lithium nitrate (LiNO 3 ) was introduced into 70% H₂O₂, which successfully shortened the ignition delay time from 46 ms to 27 ms.And the specific impulse calculation results showed that Fc-6 exhibited the highest specific impulse of 249.9 s with 70% H 2 O 2 + 30% LiNO 3 . Moreover, the hypergolic ignition mechanism revealed a dual-pathway ignition process: (1) ferrocenemediated electron transfer accelerated H₂O₂ decomposition into •OH radicals, and (2) borane oxidation released huge amounts of heat, igniting flammable small-molecule.