Influence of Morphology and Crystallinity on Surface Reactivity of Nanosized Anatase TiO2 Studied by Adsorption Techniques. 1. The Use of Gaseous Molecular Probes

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• 作者：Mouhamad Ali Ahmad ; Benedicte Prelot ; Angelina Razafitianamaharavo ; Jean Marc Douillard ; Jerzy Zajac ; Fabien Dufour ; Olivier Durupthy ; Corinne Chaneac ; Fr茅d茅ric Villi茅ras
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：November 26, 2012
• 年：2012
• 卷：116
• 期：46
• 页码：24596-24606
• 全文大小：578K
• 年卷期：v.116,no.46(November 26, 2012)
• ISSN：1932-7455

文摘

Various titanium dioxide nanoparticles were prepared by sol鈥揼el method in order to obtain samples showing different sizes and morphologies. An original approach based on the adsorption of gaseous molecules from the gas phase was proposed to gain information about surface energy of nanosized TiO₂ anatase in terms of interfacial reactivity and heterogeneity. Argon, nitrogen, and ammonia were selected as such surface molecular probes. The mainly observed crystallographic faces of anatase particles were the {101} and {001} surfaces together with the {100} one. Their abundance was correlated with the energy distribution inferred from the local isotherms of argon adsorption in the low-pressure range. The acid character of the anatase surface was probed by nitrogen molecules, and, consequently, the location of polar sites on the particle surface could be determined in correlation with the argon adsorption domains. Moreover, the number and the strength of surface acid sites were evaluated with the aid of two-cycle adsorption of gaseous ammonia supplemented by appropriate flow microcalorimetry measurements. This molecular probe revealed significant differences among the samples depending on their crystal shape or face distribution.