Abstract
A novel strategy for the synthesis of mesoporous metal oxide polyhedra with empty nanovoids by introducing nanoscale Kirkendall diffusion into a spray pyrolysis process is suggested. In this study, NiSe polyhedra with high index facets synthesized by one-pot spray pyrolysis were transformed into mesoporous NiO polyhedra with empty nanovoids by a facile oxidation process at 500 °C through nanoscale Kirkendall diffusion. Details of the formation mechanism of these uniquely structured NiO polyhedra were also studied. In the initial oxidation step, a thin NiO layer was formed on the surface of the NiSe polyhedra. The fast diffusion of Ni cations out through the NiO layer and the melting of the remaining metalloid Se formed a porous Se layer. The formation of a mesoporous NiO layer then enabled the penetration of oxygen gas by gas phase diffusion. The diffusion of metalloid Se into the mesopores of NiO and its reaction with oxygen gas formed SeO 2 nanocrystals which then evaporated into the gas phase. The step-by-step oxidation of the NiSe crystals therefore resulted in mesoporous NiO polyhedra with empty nanovoids. When used as an anode material in a lithium ion battery, mesoporous NiO polyhedra with empty nanovoids showed superior cycling and rate performance compared to anodes fabricated from dense-structured NiSe polyhedra and commercial NiO nanopowders. The mesoporous NiO polyhedra showed a high discharge capacity of 1072 mA h g −1 after 200 cycles at a current density of 1.0 A g −1 and they showed a high reversible capacity of 453 mA h g −1 , even at a high current density of 15.0 A g −1 .
Original language | English |
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Pages (from-to) | 597-605 |
Number of pages | 9 |
Journal | Applied Surface Science |
Volume | 464 |
DOIs | |
Publication status | Published - 2019 Jan 15 |
Bibliographical note
Publisher Copyright:© 2018 Elsevier B.V.
Keywords
- Kirkendall effect
- Lithium ion batteries
- Mesoporous structure
- Nickel oxide
- Spray pyrolysis
ASJC Scopus subject areas
- General Chemistry
- Condensed Matter Physics
- General Physics and Astronomy
- Surfaces and Interfaces
- Surfaces, Coatings and Films