title: Improved hydrogen storage kinetics of nanoconfined NaAlH₄ catalyzed with TiCl₃ nanoparticles.
abstract: Nanoparticles of NaAlH(4) 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 TiCl(3) to obtain an aerogel doped with 3.0 wt % TiCl(3) nanoparticles. NaAlH(4) was melt-infiltrated into the functionalized carbon aerogel at 189 °C and p(H(2)) ∼ 186-199 bar. Energy-dispersive spectrometry (EDS) combined with focused ion beam (FIB) techniques revealed the presence of Na, Al, Ti, and Cl inside the aerogel scaffold material. The infiltrated NaAlH(4) was X-ray amorphous, whereas (27)Al magic-angle spinning (MAS) NMR spectroscopy confirmed the presence of nanoconfined NaAlH(4). Temperature-programmed desorption mass spectroscopy (TPD-MS) and Sieverts' measurements demonstrated significantly improved hydrogen desorption kinetics for this new nanoconfined NaAlH(4)-TiCl(3) material as compared to nanoconfined NaAlH(4) without the catalysts TiCl(3) and to bulk ball-milled samples of NaAlH(4)-TiCl(3). We find that the onset temperature for hydrogen release was close to room temperature (T(onset) = 33 °C), and the hydrogen release rate reached a maximum value at 125 °C, which demonstrates favorable synergetic effects between nanoconfinement and catalyst addition.
authors: Center for Energy Materials, Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, DK-8000 Aarhus, Denmark.
authors: Thomas K
authors: TK
authors: Nielsen
authors: Marek
authors: M
authors: Polanski
authors: Dariusz
authors: D
authors: Zasada
authors: Payam
authors: P
authors: Javadian
authors: Flemming
authors: F
authors: Besenbacher
authors: Jerzy
authors: J
authors: Bystrzycki
authors: Jørgen
authors: J
authors: Skibsted
authors: Torben R
authors: TR
authors: Jensen
mesh_terms: D000042:Absorption; D002713:Chlorine / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry* / Q000302:isolation & purification*; D007700:Kinetics; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D014025:Titanium / Q000737:chemistry*
chemical_list: D002713:Chlorine; D006859:Hydrogen; D014025:Titanium