Journal article
Nickel Oxide Reduction by Hydrogen: Kinetics and Structural Transformations
Journal of physical chemistry. C, v 119(28), pp 16131-16138
16 Jul 2015
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
We studied the reduction kinetics of bulk NiO crystals by hydrogen and the corresponding structural transformations in the temperature range of 543-1593 K. A new experimental approach allows us to arrest and quench the reaction at different stages with millisecond time resolution. Two distinctive temperature intervals are found where the reaction kinetics and product microstructures are different. At relatively low temperatures, 543773 K, the kinetic curves have a sigmoidal shape with long induction times (up to 2000 s) and result in incomplete conversion. Low-temperature reduction forms a complex polycrystalline Ni/NiO porous structure with characteristic pore size on the order of 100 nm. No induction period was observed for the high-temperature conditions (1173-1593 K), and full reduction of NiO to Ni is achieved within seconds. An extremely fine porous metal structure, with pore size under 10 nm, forms during high-temperature reduction by a novel crystal growth mechanism. This consists of the epitaxial-like transformation of micrometer-sized NiO single crystals into single-crystalline Ni without any crystallographic changes, including shape, size, or crystal orientation. The Avrami nucleation model accurately describes the reaction kinetics in both temperature regimes. However, the structural transformations during reduction in both nanolevel and atomic level are very complex, and the mechanism relies on both nucleation and the critical diffusion length for outward diffusion of water molecules.
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Details
- Title
- Nickel Oxide Reduction by Hydrogen: Kinetics and Structural Transformations
- Creators
- Khachatur V. Manukyan - University of Notre DameArpi G. Avetisyan - Institute of Chemical Physics NAS RAChristopher E. Shuck - University of Notre DameHakob A. Chatilyan - Institute of Chemical Physics NAS RASergei Rouvimov - University of Notre DameSuren L. Kharatyan - Yerevan State UniversityAlexander S. Mukasyan - University of Notre Dame
- Publication Details
- Journal of physical chemistry. C, v 119(28), pp 16131-16138
- Publisher
- American Chemical Society; Washington, DC
- Number of pages
- 8
- Grant note
- AR 13RF-057//13-03-90604 / Russian Foundation for Basic Research; Russian Foundation for Basic Research (RFBR) AR 13RF-057//13-03-90604) / State Committee of Science of Armenia
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Materials Science and Engineering
- Web of Science ID
- WOS:000358337700039
- Scopus ID
- 2-s2.0-84937118577
- Other Identifier
- 991019296792304721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Chemistry, Physical
- Materials Science, Multidisciplinary
- Nanoscience & Nanotechnology