Probing the structure, stability and hydrogen storage properties of calcium dodecahydro-closo-dodecaborate

Journal Article · Sat May 15 00:00:00 EDT 2010 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2010.03.026· OSTI ID:21372602

Stavila, Vitalie ^[1]; Her, Jae-Hyuk; Wei, Zhou ^[2]; Hwang, Son-Jong; Kim, Chul ^[3]; Ottley, Leigh Anna M ^[4]; Udovic, Terrence J ^[2]

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1. Sandia National Laboratories, Livermore, CA 94551 (United States)
2. NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)
3. Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125 (United States)
4. Sandia National Laboratories, Albuquerque, NM 87106 (United States)

Calcium borohydride can reversibly store up to 9.6 wt% hydrogen; however, the material displays poor cyclability, generally associated with the formation of stable intermediate species. In an effort to understand the role of such intermediates on the hydrogen storage properties of Ca(BH{sub 4}){sub 2}, calcium dodecahydro-closo-dodecaborate was isolated and characterized by diffraction and spectroscopic techniques. The crystal structure of CaB{sub 12}H{sub 12} was determined from powder XRD data and confirmed by DFT and neutron vibrational spectroscopy studies. Attempts to dehydrogenate/hydrogenate mixtures of CaB{sub 12}H{sub 12} and CaH{sub 2} were made under conditions known to favor partial reversibility in calcium borohydride. However, up to 670 K no notable formation of Ca(BH{sub 4}){sub 2} (during hydrogenation) or CaB{sub 6} (during dehydrogenation) occurred. It was demonstrated that the stability of CaB{sub 12}H{sub 12} can be significantly altered using CaH{sub 2} as a destabilizing agent to favor the hydrogen release. - Graphical abstract: Calcium dodecahydro-closo-dodecaborate, CaB{sub 12}H{sub 12} (1), was isolated by dehydration/desolvation of [Ca(H{sub 2}O){sub 7}][B{sub 12}H{sub 12}].H{sub 2}O (2) or [Ca(H{sub 2}O){sub 5}(MeCN){sub 2}][B{sub 12}H{sub 12}] (3). The crystal structure of 1 was determined by powder X-ray diffraction and confirmed by neutron vibrational spectroscopy and first-principles calculations. Hydrogen storage properties of 1 in the presence of calcium hydride were elucidated.

• OSTI ID: 21372602
• Journal Information: Journal of Solid State Chemistry, Vol. 183, Issue 5; Other Information: DOI: 10.1016/j.jssc.2010.03.026; PII: S0022-4596(10)00116-7; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BOROHYDRIDES
CALCIUM BORIDES
CALCIUM HYDRIDES
CRYSTAL STRUCTURE
DEHYDRATION
DEHYDROGENATION
DENSITY FUNCTIONAL METHOD
HYDROGEN
HYDROGEN STORAGE
HYDROGENATION
NEUTRON DIFFRACTION
SPECTROSCOPY
STABILITY
X-RAY DIFFRACTION
ALKALINE EARTH METAL COMPOUNDS
BORIDES
BORON COMPOUNDS
CALCIUM COMPOUNDS
CALCULATION METHODS
CHEMICAL REACTIONS
COHERENT SCATTERING
DIFFRACTION
ELEMENTS
HYDRIDES
HYDROGEN COMPOUNDS
NONMETALS
SCATTERING
STORAGE
VARIATIONAL METHODS