Ternary LiBH4–MgH2–NaAlH4 hydride confined into nanoporous carbon host for reversible hydrogen storage.

Ternary hydride of LiBH 4 –MgH 2 –NaAlH 4 confined into carbo n aerogel scaffold (CAS) via melt infiltration for reversible hydrogen storage is proposed. Nanoconfinement of hydrides into CAS is obtained together with surface occupation of some phases, such as Al and/or LiH. Regarding nanoconfinement, not only multiple-step decomposition of LiBH 4 –MgH 2 –NaAlH 4 hydride reduces to about single step, but also reduction of dehydrogenation temperature is significantly observed, for example, ∆ T up to 70 °C regarding last dehydrogenation step. Moreover, decomposition of NaBH 4 in nanoconfined sample can be done at 360 °C (dehydrogenation temperature in this study), which is 115 and 180 °C lower than that of NaBH 4 in milled LiBH 4 –MgH 2 –NaAlH 4 and bulk NaBH 4 , respectively. The reaction of LiBH 4 +NaAlH 4 →LiAlH 4 +NaBH 4 takes place during nanoconfinement and the decomposition of LiAlH 4 is observed, resulting deficient hydrogen content liberated. However, hydrogen content released (1st cycle) and reproduced (2nd–4th cycles) from this ternary hydride enhances up to 11% and 22% of full hydrogen storage capacity due to nanoconfinement. After rehydrogenation ( T =360 °C and P (H 2 )=50 bar H 2 for 12 h), NaBH 4 , MgH 2 , and Li 3 AlH 6 are reversible, whereas Li 3 AlH 6 and NaBH 4 in milled sample cannot be recovered due to deficient hydrogen pressure ( T =360 °C and P (H 2 )=80 bar) and probably evaporation of molten sodium during dehydrogenation, respectively. The latter results in inferior hydrogen content reproduced from milled sample to nanoconfined sample. [ABSTRACT FROM AUTHOR]