Improved Hydrogen Storage Kinetics of Nanoconfined NaAlH4 Catalyzed with TiCl3 Nanoparticles

Nanoparticles of NaAlH4 have been infiltrated in nanoporous carbon aerogel with Ticl(3) nanoparticles in order to explore possible synergetic effects between nanoconfinement and a functionalized catalytic scaffold. Resorcinol formaldehyde carbon aerogels with an average pore size of 17 nm and total pore volume of 1.26 mL/g were infiltrated with TiCl3 to obtain an aerogel doped with 3.0 wt % TiCl3 nanoparticles. NaAlH4 was melt-infiltrated into the functionalized carbon aerogel at 189 degrees C and p(H-2) similar to 186-199 bar. Energy-dispersive spectrometry (EDS) combined with focused Ion beam (FIB) techniques revealed the presence of Na, Al, Tl, and Cl inside the aerogel scaffold material. The infiltrated NaAlH4 was X-ray amorphous, whereas Al-27 magic-angle spinning (MAS) NMR spectroscopy confirmed the presence of nanoconfined NaAlH4. Temperature-programmed desorption mass spectroscopy (TPD-MS) and Sieverts' measurements demonstrated significantly improved hydrogen desorption kinetics for this new nanoconfined NaAlH4-TiCl3 material as compared to nanoconfined NaAlH4 without the catalysts Ticl(3) and to bulk ball-milled samples of NaAlH4-TiCl3. We find that the onset temperature for hydrogen release was close to room temperature (T-onset = 33 degrees C, and the hydrogen release rate reached a maximum value at 125 degrees C, which demonstrates favorable synergetic effects between nanoconfinement and catalyst addition.