期刊
JOURNAL OF MATERIALS CHEMISTRY
卷 19, 期 37, 页码 6804-6809出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/b909225k
关键词
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资金
- NSERC
- CFI
- OIT
- CRC (TKS)
- National Science Foundation of China [5060211, 50872026]
- Centre for Chemical Physics at UWO
We report an X-ray absorption near edge structure (XANES) investigation of several TiO2 nanotube arrays, including the as-prepared nanotube arrays from electrochemical anodic oxidation of Ti foil (as-prepared ATNTA), as-prepared nanotube arrays after annealing at 580 degrees C (annealed ATNTA) and annealed ATNTA after electrochemical intercalation with Li (Li-intercalated ATNTA). XANES at the O K-edge and Ti L-3,L-2 and K edges shows distinctly different spectral features for the as-prepared and the annealed ATNTA, characteristic of amorphous and anatase structures, respectively. Intercalation of Li into annealed ATNTA induces a surprising, yet spectroscopically unmistakable, anatase to rutile transition. XANES at the Li K-edge clearly shows ionic features of Li in ATNTA. The charge relocation from Ti 3d to O 2p at the conduction band in TiO2 was also observed when Li ions were intercalated into annealed ATNTA albeit no noticeable reduction of Ti4+ to Ti3+ was observed. The O K-edge shows a distinctly enhanced feature in the multiple scattering regime, indicating a close to linear O-Li-O arrangement in Li-intercalated ATNTA. These results show bonding changes between Ti and O resulting from the interaction of Li ions in the TiO2 lattices. Such bonding variation has also been supported by X-ray excited optical luminescence (XEOL), which suggests Li+-defect interactions. The implications of these results are discussed.
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