Solid-State 13C NMR Characterization of Carbon-Modified TiO2

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• 作者：Erin M. Rockafellow ; Xiaowen Fang ; Brian G. Trewyn ; Klaus Schmidt-Rohr* ; William S. Jenks*
• 刊名：Chemistry of Materials
• 出版年：2009
• 出版时间：April 14, 2009
• 年：2009
• 卷：21
• 期：7
• 页码：1187-1197
• 全文大小：437K
• 年卷期：v.21,no.7(April 14, 2009)
• ISSN：1520-5002

文摘

¹³C-modified TiO₂ was prepared to facilitate study of the dopant atoms and trace their chemical fate throughout the process. In the preannealed material, NMR showed strong evidence of many Ti−O−C bonds. After annealing, surface-bound coke is a major component. NMR also showed that a washing step before annealing led to the generation of orthocarbonate (C(OR)₄) centers, observed at 126 ppm, which are located deep inside the TiO₂ particles. Both NMR and XPS confirmed the presence of small amounts of regular sp²-hybridized carbonate species in all briefly annealed samples, while annealing for longer times led to a reduction removal of the CO_n centers. Quantitative NMR also shows the degree of carbon loss that accompanies annealing. Some variation in the chemical degradation of quinoline is noted among the catalysts, but coke-containing TiO₂ catalysts are not qualitatively better catalysts for use with visible light with this substrate.