Combined X-ray and Raman Studies on the Effect of Cobalt Additives on the Decomposition of Magnesium Borohydride

Olena Zavorotynska, Stefano Deledda, Jenny G. Vitillo, Ivan Saldan, Matylda N. Guzik, Marcello Baricco, John C. Walmsley, Jiri Muller and Bjørn C. Hauback
Additional contact information
Olena Zavorotynska: Physics Department, Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027, Norway
Stefano Deledda: Physics Department, Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027, Norway
Jenny G. Vitillo: Department of Chemistry, Centre for Nanostructured Interfaces and Surfaces (NIS), National Interuniversity Consortium of Materials Science and Technology (INSTM), University of Turin, Via P. Giuria 7, Turin 10125, Italy
Ivan Saldan: Physics Department, Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027, Norway
Matylda N. Guzik: Physics Department, Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027, Norway
Marcello Baricco: Department of Chemistry, Centre for Nanostructured Interfaces and Surfaces (NIS), National Interuniversity Consortium of Materials Science and Technology (INSTM), University of Turin, Via P. Giuria 7, Turin 10125, Italy
John C. Walmsley: SINTEF Materials & Chemistry, Trondheim NO-7465, Norway
Jiri Muller: Physics Department, Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027, Norway
Bjørn C. Hauback: Physics Department, Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027, Norway

Energies, 2015, vol. 8, issue 9, 1-18

Abstract: Magnesium borohydride (Mg(BH 4 ) 2 ) is one of the most promising hydrogen storage materials. Its kinetics of hydrogen desorption, reversibility, and complex reaction pathways during decomposition and rehydrogenation, however, present a challenge, which has been often addressed by using transition metal compounds as additives. In this work the decomposition of Mg(BH 4 ) 2 ball-milled with CoCl 2 and CoF 2 additives, was studied by means of a combination of several in-situ techniques. Synchrotron X-ray diffraction and Raman spectroscopy were used to follow the phase transitions and decomposition of Mg(BH 4 ) 2 . By comparison with pure milled Mg(BH 4 ) 2 , the temperature for the γ → ε phase transition in the samples with CoF 2 or CoCl 2 additives was reduced by 10–45 °C. In-situ Raman measurements showed the formation of a decomposition phase with vibrations at 2513, 2411 and 766 cm −1 in the sample with CoF 2 . Simultaneous X-ray absorption measurements at the Co K-edge revealed that the additives chemically transformed to other species. CoF 2 slowly reacted upon heating till ~290 °C, whereas CoCl 2 transformed drastically at ~180 °C.

Keywords: cobalt additives; hydrogen storage; in-situ; magnesium borohydride (Mg(BH 4 ) 2 ); X-ray absorption spectroscopy (XAS); synchrotron X-ray diffraction (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2015
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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