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Title: Towards direct synthesis of alane: A predicted defect-mediated pathway confirmed experimentally

Here, alane (AlH 3) is a unique energetic material that has not found a broad practical use for over 70 years because it is difficult to synthesize directly from its elements. Using density functional theory, we examine the defect-mediated formation of alane monomers on Al(111) in a two-step process: (1) dissociative adsorption of H 2 and (2) alane formation, which are both endothermic on a clean surface. Only with Ti dopant to facilitate H 2 dissociation and vacancies to provide Al adatoms, both processes become exothermic. In agreement, in situ scanning tunneling microscopy showed that during H 2 exposure, alane monomers and clusters form primarily in the vicinity of Al vacancies and Ti atoms. Moreover, ball milling of the Al samples with Ti (providing necessary defects) showed a 10 % conversion of Al into AlH 3 or closely related species at 344 bar H 2, indicating that the predicted pathway may lead to the direct synthesis of alane from elements at pressures much lower than the 104 bar expected from bulk thermodynamics.
Authors:
ORCiD logo [1] ;  [1] ;  [2] ; ORCiD logo [3] ; ORCiD logo [4] ;  [5] ;  [5] ; ORCiD logo [6] ;  [1] ; ORCiD logo [7]
  1. Ames Lab., Ames, IA (United States)
  2. Ames Lab., Ames, IA (United States); Univ. of Illinois Urbana-Champaign, Urbana, IL (United States)
  3. Univ. of Illinois Urbana-Champaign, Urbana, IL (United States); Ames Lab. and Iowa State Univ., Ames, IA (United States)
  4. Univ. of Illinois Urbana-Champaign, Urbana, IL (United States); Univ. of Pittsburgh, Pittsburgh, PA (United States)
  5. Univ. of Illinois Urbana-Champaign, Urbana, IL (United States)
  6. Univ. of Illinois Urbana-Champaign, Urbana, IL (United States); Univ. of Wisconsin, Madison, WI (United States)
  7. Ames Lab. and Iowa State Univ., Ames, IA (United States)
Publication Date:
Report Number(s):
IS-J-025
Journal ID: ISSN 1864-5631
Grant/Contract Number:
AC02-07CH11358
Type:
Accepted Manuscript
Journal Name:
ChemSusChem
Additional Journal Information:
Journal Volume: 9; Journal Issue: 17; Journal ID: ISSN 1864-5631
Publisher:
ChemPubSoc Europe
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1321966