Hydrogen absorption kinetics and structural features of NaA1H4 enhanced with transition meal-and Ti-based nanoparticles
The hydrogen cycled (H) planetary milled (PM) NaAlH4 + xM (x < 0.1) system (M = 30 nm Ag, 80 nm Al, 2–3 nm C, 30 nm Cr, 25 nm Fe, 30 nm Ni, 25 nm Pd, 65 nm Ti) has been studied by high resolution synchrotron powder X-ray diffraction. Isothermal absorption kinetic isotherms have been measured over...
| Main Authors: | , , , , , , , , , , |
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| Format: | Journal Article |
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Elsevier Ltd
2012
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| Online Access: | http://hdl.handle.net/20.500.11937/10795 |
| _version_ | 1848747631055994880 |
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| author | Pitt, M. Vullum, P. Sorby, M. Emerich, H. Paskevicius, Mark Webb, C. Gray, E. Buckley, Craig Walmsley, J. Holmestad, R. Hauback, B. |
| author_facet | Pitt, M. Vullum, P. Sorby, M. Emerich, H. Paskevicius, Mark Webb, C. Gray, E. Buckley, Craig Walmsley, J. Holmestad, R. Hauback, B. |
| author_sort | Pitt, M. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The hydrogen cycled (H) planetary milled (PM) NaAlH4 + xM (x < 0.1) system (M = 30 nm Ag, 80 nm Al, 2–3 nm C, 30 nm Cr, 25 nm Fe, 30 nm Ni, 25 nm Pd, 65 nm Ti) has been studied by high resolution synchrotron powder X-ray diffraction. Isothermal absorption kinetic isotherms have been measured over the first two H cycles. The PM NaAlH4 + 0.1Ti system has also been studied by high resolution transmission electron microscopy (TEM). 80 nm Al and 2–3 nm C were inactive, and would not allow hydrogen (H) desorption from NaAlH4. 30 nm Cr, 25 nm Fe, 30 nm Ni, and 25 nm Pd showed activity, but with weak kinetics of only ca. 1 wt.% H/hour. The NaAlH4 + 0.1Ti system displays absorption kinetics of ca. 7 wt.% H/hour, comparable to TiCl3 enhanced NaAlH4 after five H cycles. After H cycling the PM NaAlH4 + 0.1Ti system, we observe a body centred tetragonal (bct) χ-TiH2 phase, which displays intense anisotropic peak broadening. The broadening is evident as a massive dislocation density of ca. 1.20 × 1017/m2 in high resolution TEM images of the χ-TiH2 phase. All originally added Ti can be accounted for in the bct χ-TiH2 phase by quantitative phase analysis (QPA) after five H cycles. The PM NaH + Al + 0.02 (Ti-nano-alloy) system shows absorption kinetic rates in the order TiO2 > TiN > TiC > Ti, with rapid hydrogenation kinetics of ca. 23 wt.% H/hour for TiO2 enhanced NaAlH4, equivalent to TiCl3 enhanced NaAlH4. The TiN and TiC are partially reduced by ca. 7 and 22% respectively, and the TiO2 is completely reduced. The location of the reduced Ti cannot be discerned by X-ray diffraction at these minor proportions. |
| first_indexed | 2025-11-14T06:52:13Z |
| format | Journal Article |
| id | curtin-20.500.11937-10795 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T06:52:13Z |
| publishDate | 2012 |
| publisher | Elsevier Ltd |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-107952017-09-13T16:07:33Z Hydrogen absorption kinetics and structural features of NaA1H4 enhanced with transition meal-and Ti-based nanoparticles Pitt, M. Vullum, P. Sorby, M. Emerich, H. Paskevicius, Mark Webb, C. Gray, E. Buckley, Craig Walmsley, J. Holmestad, R. Hauback, B. synchrotron radiation hydrogen storage nanocrystalline materials mechanical milling The hydrogen cycled (H) planetary milled (PM) NaAlH4 + xM (x < 0.1) system (M = 30 nm Ag, 80 nm Al, 2–3 nm C, 30 nm Cr, 25 nm Fe, 30 nm Ni, 25 nm Pd, 65 nm Ti) has been studied by high resolution synchrotron powder X-ray diffraction. Isothermal absorption kinetic isotherms have been measured over the first two H cycles. The PM NaAlH4 + 0.1Ti system has also been studied by high resolution transmission electron microscopy (TEM). 80 nm Al and 2–3 nm C were inactive, and would not allow hydrogen (H) desorption from NaAlH4. 30 nm Cr, 25 nm Fe, 30 nm Ni, and 25 nm Pd showed activity, but with weak kinetics of only ca. 1 wt.% H/hour. The NaAlH4 + 0.1Ti system displays absorption kinetics of ca. 7 wt.% H/hour, comparable to TiCl3 enhanced NaAlH4 after five H cycles. After H cycling the PM NaAlH4 + 0.1Ti system, we observe a body centred tetragonal (bct) χ-TiH2 phase, which displays intense anisotropic peak broadening. The broadening is evident as a massive dislocation density of ca. 1.20 × 1017/m2 in high resolution TEM images of the χ-TiH2 phase. All originally added Ti can be accounted for in the bct χ-TiH2 phase by quantitative phase analysis (QPA) after five H cycles. The PM NaH + Al + 0.02 (Ti-nano-alloy) system shows absorption kinetic rates in the order TiO2 > TiN > TiC > Ti, with rapid hydrogenation kinetics of ca. 23 wt.% H/hour for TiO2 enhanced NaAlH4, equivalent to TiCl3 enhanced NaAlH4. The TiN and TiC are partially reduced by ca. 7 and 22% respectively, and the TiO2 is completely reduced. The location of the reduced Ti cannot be discerned by X-ray diffraction at these minor proportions. 2012 Journal Article http://hdl.handle.net/20.500.11937/10795 10.1016/j.ijhydene.2012.08.014 Elsevier Ltd restricted |
| spellingShingle | synchrotron radiation hydrogen storage nanocrystalline materials mechanical milling Pitt, M. Vullum, P. Sorby, M. Emerich, H. Paskevicius, Mark Webb, C. Gray, E. Buckley, Craig Walmsley, J. Holmestad, R. Hauback, B. Hydrogen absorption kinetics and structural features of NaA1H4 enhanced with transition meal-and Ti-based nanoparticles |
| title | Hydrogen absorption kinetics and structural features of NaA1H4 enhanced with transition meal-and Ti-based nanoparticles |
| title_full | Hydrogen absorption kinetics and structural features of NaA1H4 enhanced with transition meal-and Ti-based nanoparticles |
| title_fullStr | Hydrogen absorption kinetics and structural features of NaA1H4 enhanced with transition meal-and Ti-based nanoparticles |
| title_full_unstemmed | Hydrogen absorption kinetics and structural features of NaA1H4 enhanced with transition meal-and Ti-based nanoparticles |
| title_short | Hydrogen absorption kinetics and structural features of NaA1H4 enhanced with transition meal-and Ti-based nanoparticles |
| title_sort | hydrogen absorption kinetics and structural features of naa1h4 enhanced with transition meal-and ti-based nanoparticles |
| topic | synchrotron radiation hydrogen storage nanocrystalline materials mechanical milling |
| url | http://hdl.handle.net/20.500.11937/10795 |