Facilitated Lattice Oxygen Depletion in Consolidated TiO2 Nanocrystal Ensembles: A Quantitative Spectroscopic O2 Adsorption Study

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• 作者：Michael J. Elser ; Oliver Diwald
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：February 2, 2012
• 年：2012
• 卷：116
• 期：4
• 页码：2896-2903
• 全文大小：502K
• 年卷期：v.116,no.4(February 2, 2012)
• ISSN：1932-7455

文摘

On TiO₂ nanocrystal powders, pressure-induced consolidation and subsequent annealing generates mesopores inside the pellet and leads to the depletion of specific surface area. This loss corresponds to the introduction of particle鈥損article interfaces and grain boundaries. In previous work, they were found to be susceptible to facilitated lattice oxygen depletion as compared to free particle surfaces during vacuum annealing. For the first time, we determined the adsorption of molecular oxygen on these consolidated and nonstoichiometric nanocrystal samples. As a function of repeated cycles of vacuum annealing and O₂ exposure, the amount of paramagnetic and diamagnetic surface oxygen species was determined using mass spectroscopy in combination with FT-IR, electron paramagnetic resonance (EPR), and UV鈥搗is鈥揘IR diffuse reflectance.