title: Hydrogen-deuterium exchange experiments to probe the decomposition reaction of sodium alanate.
abstract: NaAlH(4) is the archetypical complex hydride for hydrogen storage. The extraordinary effect of dopants on the sorption kinetics triggered the investigation of this empirical finding. In this paper, a short review of the state of the art is given. To gain further understanding of the mechanisms involved we label the interacting species during the sorption process. This was experimentally realized by hydrogen-deuterium exchange measurements during the decomposition of NaAlH(4) followed by thermogravimetry, Raman spectroscopy and mass spectrometry. By these experiments we are able to obtain specific information on the diffusing species and formation of intermediates. The activation energy of tracer diffusion in NaAlH(4) is found to be 0.28 eV. The results are evidence for a vacancy-mediated desorption process of NaAlH(4).
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory 138-Hydrogen & Energy, Uberlandstrasse 129, Dübendorf, Switzerland. andreas.borgschulte@empa.ch
authors.forename: A
authors.initials: A
authors.lastname: Borgschulte
authors.forename: A
authors.initials: A
authors.lastname: Züttel
authors.forename: P
authors.initials: P
authors.lastname: Hug
authors.forename: G
authors.initials: G
authors.lastname: Barkhordarian
authors.forename: N
authors.initials: N
authors.lastname: Eigen
authors.forename: M
authors.initials: M
authors.lastname: Dornheim
authors.forename: R
authors.initials: R
authors.lastname: Bormann
authors.forename: A J
authors.initials: AJ
authors.lastname: Ramirez-Cuesta
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D002384:Catalysis; D003198:Computer Simulation; D003903:Deuterium / Q000737:chemistry*; D041961:Deuterium Exchange Measurement; D006859:Hydrogen / Q000737:chemistry*; D017670:Sodium Compounds / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013059:Spectrum Analysis, Raman; D013818:Thermogravimetry
chemical_list: D017607:Aluminum Compounds; D017670:Sodium Compounds; C513667:sodium aluminum hydride; D006859:Hydrogen; D003903:Deuterium