Erratum to “Chemical state of Ti in sodium alanate doped with TiCl3 using X-ray photoelectron spectroscopy” [J. Alloys Compd. 404–406 (2005) 766–770]

Reactivity enhancement of oxide skins in reversible Ti-doped NaAlH4

“…% TiCl 3 , resulting in NaAlH 4 , Ti species, NaCl and Al. 24 The corresponding XP-overview spectrum is shown in Fig. 1, showing all expected elements in their chemical state which is in good agreement with earlier research.…”

“…1, showing all expected elements in their chemical state which is in good agreement with earlier research. 24,25 Besides the expected XPS and Auger lines of the two main elements Na and Al present in the specimen, oxygen and carbon contamination are also clearly visible. The Ti 2p orbital from the dopant is also present, intense enough for qualitative and quantitative analysis (to be detailed below).…”

“…However, as shown by Léon et al, the Cl concentration on the hydride surface is very sensitive to the milling conditions. 24 After survey spectrum acquisition, the specimen has been heated from 310 K to 380 K at 0.25 K/min and its decomposition has been followed in-situ. NaAlH 4 decomposes in two steps, releasing theoretically 5.6 mass % of hydrogen: 27,28 3NaAlH 4 → Na 3 AlH 6 + 2AlH 3 → Na 3 AlH 6 + 2Al + 3H 2 (1)…”

“…The observation of an oxide layer on a hydride surface is not surprising, namely in the case of sodium alanate. 24 Usually, this oxide layer is seen as a stable hydrogen diffusion barrier, and thereby as a limiting factor in the dehydriding kinetics. 16,38,39 But in certain cases, e.g.…”

“…X-ray absorption spectroscopy 9,36,44,45 ) and XPS. 24,32 However, it has also been found that different Ti species in oxidized and reduced form are present after doping. These findings make it difficult to correctly describe the catalytically active species and corresponding mechanism.…”