Stavila Vitalie, Li Sichi, Dun Chaochao, Marple Maxwell A T, Mason Harris E, Snider Jonathan L, Reynolds Joseph E, El Gabaly Farid, Sugar Joshua D, Spataru Catalin D, Zhou Xiaowang, Dizdar Brennan, Majzoub Eric H, Chatterjee Ruchira, Yano Junko, Schlomberg Hendrik, Lotsch Bettina V, Urban Jeffrey J, Wood Brandon C, Allendorf Mark D
Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94550, USA.
Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA, 94550, USA.
Angew Chem Int Ed Engl. 2021 Dec 1;60(49):25815-25824. doi: 10.1002/anie.202107507. Epub 2021 Oct 5.
The highly unfavorable thermodynamics of direct aluminum hydrogenation can be overcome by stabilizing alane within a nanoporous bipyridine-functionalized covalent triazine framework (AlH @CTF-bipyridine). This material and the counterpart AlH @CTF-biphenyl rapidly desorb H between 95 and 154 °C, with desorption complete at 250 °C. Sieverts measurements, Al MAS NMR and Al{ H} REDOR experiments, and computational spectroscopy reveal that AlH @CTF-bipyridine dehydrogenation is reversible at 60 °C under 700 bar hydrogen, >10 times lower pressure than that required to hydrogenate bulk aluminum. DFT calculations and EPR measurements support an unconventional mechanism whereby strong AlH binding to bipyridine results in single-electron transfer to form AlH (AlH ) clusters. The resulting size-dependent charge redistribution alters the dehydrogenation/rehydrogenation thermochemistry, suggesting a novel strategy to enable reversibility in high-capacity metal hydrides.
通过在纳米多孔联吡啶功能化共价三嗪框架（AlH@CTF-联吡啶）中稳定铝烷，可以克服直接氢化铝极为不利的热力学问题。这种材料以及对应的AlH@CTF-联苯在95至154°C之间迅速解吸氢气，在250°C时解吸完成。Sieverts测量、Al MAS NMR和Al{H} REDOR实验以及计算光谱表明，AlH@CTF-联吡啶脱氢在60°C、700 bar氢气条件下是可逆的，压力比氢化块状铝所需的压力低10倍以上。DFT计算和EPR测量支持一种非常规机制，即AlH与联吡啶的强结合导致单电子转移，形成AlH（AlH）簇。由此产生的尺寸依赖性电荷重新分布改变了脱氢/再氢化热化学，为实现高容量金属氢化物的可逆性提供了一种新策略。
