Nanoscopic Al1−xCex phases in the NaH + Al + 0.02CeCl3 system

Hydrogen absorption kinetics and structural features of NaAlH4 enhanced with transition-metal and Ti-based nanoparticles

“…1200 USD [9]) at a 2 mol% additive level is a factor of 120. Similar calculations for the most efficient CeCl 3 based additive for NaAlH 4 [11] also show a factor of 20 in cost (ca. 28,000 USD [12]) compared to TiO 2 .…”

“…Our previous studies demonstrate that Al 1Àx Ti x phases that form on the NaAlH 4 surface are typically 4e25 nm [3,20e22], and similarly, Al 1Àx TM x phases (where TM is a transition metal) for all other period 1 and 2 TMCl n enhanced NaAlH 4 samples [23] are < 50 nm. Attempts to comill Al 3 Ti with NaAlH 4 have produced similarly poor kinetic enhancement due to the use of micron sized Al 3 Ti, discussed extensively in [11]. It is clear that any metal or alloy phase that is co-milled with NaAlH 4 should be nanoscopic in dimension, and less than ca.…”

“…As has been emphasized in [24] for the metallic Ti (À325 mesh) additive, NaH þ Al þ 0.04Ti samples milled under H 2 display faster kinetics than those milled under Ar for the same period. Long milling periods under H 2 gas (tens to hundreds of hours) are necessary to reduce micron sized powders to nanoscopic dimensions, discussed in detail for the case of Al 3 Ti and Al 1Àx Ce x addition to NaAlH 4 in [11].…”

Complex Metal Hydrides for Hydrogen, Thermal and Electrochemical Energy Storage

“…However, the useful capacity is low (5.6 wt % H 2 ) and not ideal for consideration in mobile applications. Thus, a tremendous effort has been carried out in research to tailor the system, e.g., by addition of dopants or nanoconfinement [70][71][72][73][74][75][76][77]. Furthermore, NaAlH 4 has also been widely used as a precursor in metathesis reactions to synthesize new metal alanate compounds, e.g., Mg(AlH 4 ) 2 , Ca(AlH 4 ) 2 , Sr(AlH 4 ) 2 , and Eu(AlH 4 ) 2 [78][79][80].…”

Nanoconfinement degradation in NaAlH4/CMK-1

“…Many of these transition metal catalysts are added to the NaAlH 4 system as halide salts, that are reduced to metal-Al surface-alloys that are catalytically active, with the generation of an inactive sodium halide salt by-product [11]. Although the list of catalytic phases for NaAlH 4 is extensive, recent focus on CeCl 3 [12] or Ti-based nanoparticles [13] show great promise, even when compared to the well-studied TiCl 3 doped NaAlH 4 system [10].…”