title: Effect of particle size on hydrogen release from sodium alanate nanoparticles.
abstract: Density functional theory and the cluster expansion method are used to model 2-10 nm sodium alanate (NaAlH(4)) nanoparticles and related decomposition products Na(3)AlH(6), NaH, and Al. While bulk sodium alanate releases hydrogen in a two-step process, our calculations predict that below a certain size sodium alanate nanoparticles decompose in a single step directly to NaH, Al, and H(2) due to the effect of particle size on decomposition thermodynamics. This may explain why sodium alanate nanoparticles, unlike bulk sodium alanate, have been observed to release hydrogen in the operating temperature range of proton exchange membrane fuel cells. In addition, we identify low-energy surfaces that may be important for the dynamics of hydrogen storage and release from sodium alanate nanoparticles.
authors.affiliation: Massachusetts Institute of Technology, 77 Massachusetts Avenue 13-5056, Cambridge, Massachusetts 02139, USA.
authors.forename: Tim
authors.initials: T
authors.lastname: Mueller
authors.forename: Gerbrand
authors.initials: G
authors.lastname: Ceder
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D003198:Computer Simulation; D011211:Electric Power Supplies; D006859:Hydrogen / Q000737:chemistry*; D007700:Kinetics; D008422:Materials Testing; D015233:Models, Statistical; D009010:Monte Carlo Method; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D017670:Sodium Compounds / Q000737:chemistry*
chemical_list: D017607:Aluminum Compounds; D017670:Sodium Compounds; C513667:sodium aluminum hydride; D006859:Hydrogen