Huang Jia-Hong, Ji Ao-Qi, Wang Zhao-Yang, Wang Qian-You, Zang Shuang-Quan
Henan Key Laboratory of Crystalline Molecular Functional Materials, and College of Chemistry, Zhengzhou University, Zhengzhou, 450001, China.
Adv Sci (Weinh). 2024 Jun;11(23):e2401861. doi: 10.1002/advs.202401861. Epub 2024 Apr 3.
Hypergolic propellants rely on fuel and oxidizer that spontaneously ignite upon contact, which fulfill a wide variety of mission roles in launch vehicles and spacecraft. Energy-rich carboranes are promising hypergolic fuels, but triggering their energy release is quite difficult because of their ultrastable aromatic cage structure. To steer the development of carborane-based high-performance hypergolic material, carboranylthiolated compounds integrated with atomically precise copper clusters are presented, yielding two distinct isomers, Cu and Cu, both possessing similar ligands and core structures. With the migration of thiolate groups from carbon atoms to boron atoms, the ignition delay (ID) time shortened from 6870 to 3 ms when contacted with environmentally benign oxidizer high-test peroxide (HTP, with a HO concentration of 90%). The extraordinarily short ignition ID time of Cu is ranking among the best of HTP-active hypergolic materials. The experimental and theoretical findings reveal that benefitting from the migration of thiolate groups, Cu, characterized by an electron-rich metal kernel, displays enhanced reducibility and superior charge transfer efficiency. This results in exceptional activation rates with HTP, consequently inducing carborane combustion and the simultaneous release of energy. This fundamental investigation shed light on the development of advanced green hypergolic propulsion systems.
自燃推进剂依赖于燃料和氧化剂，它们在接触时会自燃，在运载火箭和航天器中发挥着各种各样的任务作用。富含能量的碳硼烷是很有前景的自燃燃料，但由于其超稳定的芳香笼状结构，触发其能量释放相当困难。为了推动基于碳硼烷的高性能自燃材料的发展，本文提出了与原子精确的铜簇结合的碳硼烷硫醇化化合物，产生了两种不同的异构体，Cu和Cu，它们都具有相似的配体和核心结构。随着硫醇盐基团从碳原子迁移到硼原子，与环境友好型氧化剂高试过氧化氢（HTP，过氧化氢浓度为90%）接触时，点火延迟（ID）时间从6870毫秒缩短到3毫秒。Cu异常短的点火ID时间跻身于HTP活性自燃材料的最佳之列。实验和理论结果表明，得益于硫醇盐基团的迁移，以富电子金属核为特征的Cu表现出增强的还原性和卓越的电荷转移效率。这导致与HTP的活化速率异常高，从而引发碳硼烷燃烧并同时释放能量。这项基础研究为先进绿色自燃推进系统的发展提供了启示。
