A novel catalytic route for hydrogenation-dehydrogenation of 2LiH+MgB2 via in situ formed core-shell LixTiO2 nanoparticles

作者：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; von Colbe J M Bellosta; Dornheim M

来源：Journal of Materials Chemistry A, 2017, 5(25): 12922-12933.

DOI：10.1039/c7ta03117c

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 degrees C a 1 mol% TiO2 doped Li-RHC material shows sustainable hydrogen capacity of similar to 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.

• 出版日期2017-7-7