Manipulating the d-band center of Cu(i)-MOFs for the catalytic ignition of [BMIM]N(CN)2 IL-H2O2 propellants

Abstract

A solution to the intrinsic ignition problem facing novel ionic liquid-H₂O₂ propellants is urgently needed for them to achieve aerospace applications. We addressed this issue by tuning the d-band center to adjust the adsorption strength of the catalyst for IL/H₂O₂ toward the optimal value, thus enhancing its catalytic activity for the efficient decomposition of H₂O₂ to generate reactive oxygen species. Herein, the regulation of the d-band center of Cu(I) in a Cu(I)-MOF catalyst via precise ligand engineering design was studied. Remarkably, the Cu-S₃ coordination of Cu-SH′ shifts its d-band center closer to the Fermi level, promoting the adsorption of [BMIM]N(CN)₂ and H₂O₂. Cu-SH′ enables efficient H₂O₂ activation and robust ˙OH and ¹O₂ generation to trigger the rapid self-ignition of [BMIM]N(CN)₂-H₂O₂ propellant. The resulting t_id of 18.4 ms is nearly 34% lower than that achieved using the homogeneous catalyst [FcCH₂N(CH₃)₃]₂[Cu₂I₄]. This work provides fundamental insights into the design of efficient ligand-based combustion catalysts for the improved performance of rockets and spacecrafts.