Low-Temperature FTIR Study of CO Adsorption on Titania Nanotubes

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• 作者：Jos&eacute ; A. Toledo-Antonio ; Selene Capula ; M. Antonia Cort&eacute ; s-Já ; come ; Carlos Angeles-Chá ; vez ; Esteban Ló ; pez-Salinas ; Gerardo Ferrat ; Juan Navarrete ; Jos&eacute ; Escobar
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：July 26, 2007
• 年：2007
• 卷：111
• 期：29
• 页码：10799 - 10805
• 全文大小：316K
• 年卷期：v.111,no.29(July 26, 2007)
• ISSN：1932-7455

文摘

Titania nanotubes were obtained by an alkaline hydrothermal treatment of anatase at 373 K followed bywashing with an HCl aqueous solution. Samples were dried at 373 K and calcined at 573 and 673 K. Thesolids were characterized by X-ray diffraction, Raman spectroscopy, HRTEM, nitrogen physisorption, andFTIR of adsorbed CO. After calcination at 673 K, the nanotubular morphology was well-preserved, althoughinitial transformation to anatase was observed. The interlayer space between the walls of the nanotubescollapsed, resulting in domains of an anatase phase within the walls. The nanostructure obtained after calcinationat 673 K was able to adsorb CO at a low temperature (100 K). The CO molecules were adsorbed on theremaining OH groups of the nanotubes and then converted into CO₂ and CO₃^2- by increasing the desorptiontemperature. FTIR bands related to H₂O and CO₃^2- appeared concomitantly with CO adsorption and intensifiedat higher evacuation temperatures. Then, adsorbed CO was transformed into CO₂ at temperatures around 158K. After evacuation at 233 K, the adsorbed CO₂ was transformed into CO₃^2- species. These results suggestthat CO molecules are adsorbed on titania nanotubes via reaction with surface OH groups. Finally, the CO₃^2-species were eliminated, restoring the surface OH groups after evacuation at 473 K.