Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10620636 | Acta Materialia | 2011 | 10 Pages |
Abstract
In the present work, a nanoconfinement system with NaAlH4 exclusively embedded in ordered mesoporous carbon (MC) was synthesized by a three-step procedure, i.e., thermal melting impregnation plus de-/re-hydrogenation. It is demonstrated that the NaAlH4 inside MC shows faster kinetics for dehydrogenation than the kinetics of pristine NaAlH4 with a reduction in activation energy by â¼70Â kJÂ molâ1. An enhanced cycling stability is also achieved by the high-capacity retention of >80% after 15 de-/re-hydrogenation cycles. These remarkable improvements are attributed to the synergistic effects of both nanoconfinement and chemical catalysis caused by the MC, where nanoconfinement plays a dominant role. Furthermore, kinetic modeling studies suggest that the hydrogen release from the confined NaAlH4 system is governed by two processes: the initial process can be expressed by one-dimensional nucleation and growth, and the second process is jointly controlled by three-dimensional diffusion and phase boundary migration.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Y. Li, G. Zhou, F. Fang, X. Yu, Q. Zhang, L. Ouyang, M. Zhu, D. Sun,