TY - JOUR
T1 - Effect of transition metal fluorides on the sorption properties and reversible formation of Ca(BH4)2
AU - Bonatto Minella, Christian
AU - Garroni, Sebastiano
AU - Pistidda, Claudio
AU - Gosalawit-Utke, R.
AU - Barkhordarian, Gagik
AU - Rongeat, Carine
AU - Lindemann, Inge
AU - Gutfleisch, Oliver
AU - Jensen, Torben R.
AU - Cerenius, Yngve
AU - Christensen, Jeppe
AU - Baró, Maria Dolores
AU - Bormann, Rüdiger
AU - Klassen, Thomas
AU - Dornheim, Martin
PY - 2011/2/10
Y1 - 2011/2/10
N2 - Light metal borohydrides are considered as promising materials for solid state hydrogen storage. Because of the high hydrogen content of 11.5 wt % and the rather low dehydrogenation enthalpy of 32 Kj·mol-1H 2, Ca(BH4)2 is considered to be one of the most interesting compounds in this class of materials. In the present work, the effect of selected TM-fluoride (TM = transition metal) additives on the reversible formation of Ca(BH4)2 was investigated by means of thermovolumetric, calorimetric, Fourier transform infrared spectroscopy, and ex situ, and in situ synchrotron radiation powder X-ray diffraction (SR-PXD) measurements. Furthermore, selected desorbed samples were analyzed by 11B{1H} solid state magic angle spinning nuclear magnetic resonance (MAS NMR). Under the conditions used in this study (145 bar H 2 pressure and 350 °C), TiF4 and NbF5 were the only additives causing partial reversibility. In these two cases, 11B{1H} MAS NMR analyses detected CaB6 and likely CaB12H12 in the dehydrogenation products. Elemental boron was found in the decomposition products of Ca(BH4)2 samples with VF4, TiF3, and VF3. The results indicate an important role of CaB6 for the reversible formation of Ca(BH4)2. © 2011 American Chemical Society.
AB - Light metal borohydrides are considered as promising materials for solid state hydrogen storage. Because of the high hydrogen content of 11.5 wt % and the rather low dehydrogenation enthalpy of 32 Kj·mol-1H 2, Ca(BH4)2 is considered to be one of the most interesting compounds in this class of materials. In the present work, the effect of selected TM-fluoride (TM = transition metal) additives on the reversible formation of Ca(BH4)2 was investigated by means of thermovolumetric, calorimetric, Fourier transform infrared spectroscopy, and ex situ, and in situ synchrotron radiation powder X-ray diffraction (SR-PXD) measurements. Furthermore, selected desorbed samples were analyzed by 11B{1H} solid state magic angle spinning nuclear magnetic resonance (MAS NMR). Under the conditions used in this study (145 bar H 2 pressure and 350 °C), TiF4 and NbF5 were the only additives causing partial reversibility. In these two cases, 11B{1H} MAS NMR analyses detected CaB6 and likely CaB12H12 in the dehydrogenation products. Elemental boron was found in the decomposition products of Ca(BH4)2 samples with VF4, TiF3, and VF3. The results indicate an important role of CaB6 for the reversible formation of Ca(BH4)2. © 2011 American Chemical Society.
U2 - 10.1021/jp107781m
DO - 10.1021/jp107781m
M3 - Article
SN - 1932-7447
VL - 115
SP - 2497
EP - 2504
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
ER -