Defying Thermodynamics: Stabilization of Alane Within Covalent Triazine Frameworks for Reversible Hydrogen Storage

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. and Allendorf, Mark D. (2021): Defying Thermodynamics: Stabilization of Alane Within Covalent Triazine Frameworks for Reversible Hydrogen Storage. In: Angewandte Chemie-International Edition, Vol. 60, No. 49: pp. 25815-25824

Abstract

The highly unfavorable thermodynamics of direct aluminum hydrogenation can be overcome by stabilizing alane within a nanoporous bipyridine-functionalized covalent triazine framework (AlH3@CTF-bipyridine). This material and the counterpart AlH3@CTF-biphenyl rapidly desorb H-2 between 95 and 154 degrees C, with desorption complete at 250 degrees C. Sieverts measurements, 27Al MAS NMR and Al-27{H-1} REDOR experiments, and computational spectroscopy reveal that AlH3@CTF-bipyridine dehydrogenation is reversible at 60 degrees 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 AlH3 binding to bipyridine results in singleelectron transfer to form AlH2(AlH3) n clusters. The resulting size-dependent charge redistribution alters the dehydrogenation/rehydrogenation thermochemistry, suggesting a novel strategy to enable reversibility in high-capacity metal hydrides.

• Item Type: Journal article
• Faculties: Chemistry and Pharmacy > Department of Chemistry
• Subjects: 500 Science > 540 Chemistry
• ISSN: 1433-7851
• Language: English