Surfactant Induced Synthesis of LiAlH4 and NaAlH4 Nanoparticles for Hydrogen Storage

Abstract

LiAlH4 and NaAlH4 are considered to be promising hydrogen storage materials due to their high hydrogen density. However, their practical use is hampered by the lack of hydrogen reversibility along with poor kinetics. Nanosizing is an effective strategy to enable hydrogen reversibility under practical conditions. However, this has remained elusive as the synthesis of alanate nanoparticles has not been explored. Herein, a simple solvent evaporation method is demonstrated to assemble alanate nanoparticles with the use of surfactants as a stabilizer. More importantly, the roles of the surfactants in enabling control over particle size and morphology was determined. Surfactants with long linear carbon chains and matching the hard character of alanates are more prone to lead to the formation of small particles of ~10 nm due to steric hindrance. This can result in significant shifts in the temperature for hydrogen release.

LiAlH4Nanoparticles Encapsulated within Metallic Titanium Shells for Enhanced Hydrogen Storage

“…From our previous work, it was found LiAlH 4 would coordinate more strongly with surfactants with a hard character as defined by Pearson’s principle of hard and soft acid and base . Thus, it was initially expected that a hard-type surfactant such as dodecylamine (DDA) would be more effective at slowing down the reduction rate of Ti 3+ at the surface of the LiAlH 4 nanoparticles as compared to soft surfactants and ionic salts.…”

“…From our previous work, it was found LiAlH 4 would coordinate more strongly with surfactants with a hard character as defined by Pearson's principle of hard and soft acid and base. 23 Thus, it was initially expected that a hardtype surfactant such as dodecylamine (DDA) would be more effective at slowing down the reduction rate of Ti 3+ at the surface of the LiAlH 4 nanoparticles as compared to soft surfactants and ionic salts. However, determination of the reduction rates of the stabilized LiAlH 4 nanoparticles revealed that the use of DDT (of a soft character) as a LiAlH 4 nanoparticle stabilizer led to a better reduction in the rate of the Ti 3+ reaction at the surface of LiAlH 4 −DDT nanoparticles (Figure S2).…”

“…Milli-Q water was obtained from an Arium pro ultrapure water system. In this work, LiAlH 4 nanoparticles were synthesized via a solvent evaporation method using dodecanethiol (DDT) as a stabilizer . LiAlH 4 (redox potential of −3.7 to −2.25 V vs NHE) can effectively be used to reduce TiCl 3 (−1.36 V vs NHE). , …”

Enhancement of the Desorption Properties of LiAlH4 by the Addition of LaCoO3

“…The FTIR spectra were carried out to confirm the presence of 10 wt.% LaCoO3, as indicated in Figure 9. Two regions of active IR peaks that are the bending mode and the stretching mode were detected in the range of 800−900 cm −1 and 1600−1800 cm −1 [72], respectively, for pure LiAlH4, milled LiAlH4 and LiAlH4 + 10 wt.% LaCoO3. After the addition of 10 wt.% LaCoO3, a new peak was detected at 1383 cm −1 , suggesting that LiAlH4 was decomposed to Li3AlH6 and Al during the ball-milling process.…”