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  Puszkiel, J.A.; Castro Riglos, M.V.; Ramallo-Lopez, J.M.; Mizrahi, M.; Karimi, F.; Santoru, A.; Hoell, A.; Gennari, F.C.; Arneodo Larochette, P.; Pistidda, C.; Klassen, T.; Bellosta von Colbe, J.M.; Dornheim, M.: A novel catalytic route for hydrogenation-dehydrogenation of 2LiH+MgB₂ via in situ formed core-shell Li_xTiO₂ nanoparticles. Journal of Materials Chemistry A 5 (2017), p. 12922-12933

10.1039/c7ta03117c
Open Access Version (externer Anbieter)

Abstract:
A novel catalytic route for hydrogenation–dehydrogenation of 2LiH + MgB2 via in situ formed core–shell LixTiO2 nanoparticles Aiming to improve the hydrogen storage properties of 2LiH + MgB2 (Li-RHC), the effect of TiO2 addition to Li-RHC is investigated. The presence of TiO2 leads to the in situ formation of core–shell LixTiO2 nanoparticles during milling and upon heating. These nanoparticles markedly enhance the hydrogen storage properties of Li-RHC. Throughout hydrogenation–dehydrogenation cycling at 400
C a 1 mol% TiO2 doped Li-RHC material shows sustainable hydrogen capacity of 10 wt% and short hydrogenation and dehydrogenation times of just 25 and 50 minutes, respectively. The in situ formed core–shell LixTiO2 nanoparticles confer proper microstructural refinement to the Li-RHC, thus preventing the material's agglomeration upon cycling. An analysis of the kinetic mechanisms shows that the presence of the core–shell LixTiO2 nanoparticles accelerates the one-dimensional interface-controlled mechanism during hydrogenation owing to the high Li+ mobility through the LixTiO2 lattice. Upon dehydrogenation, the in situ formed core–shell LixTiO2 nanoparticles do not modify the dehydrogenation thermodynamic properties of the Li-RHC itself. A new approach by the combination of two kinetic models evidences that the activation energy of both MgH2 decomposition and MgB2 formation is reduced. These improvements are due to a novel catalytic mechanism via Li+ source/sink reversible reactions.