An Experimental and Theoretical Approach to Understanding the Surface Properties of One-Dimensional TiO2 Nanomaterials

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• 作者：Ati膽a Selmani ; Mario 艩padina ; Milivoj Plodinec ; Ida Dela膷 Marion ; Marc Georg Willinger ; Johannes L眉tzenkirchen ; Harry D. Gafney ; Engelbert Redel
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：August 27, 2015
• 年：2015
• 卷：119
• 期：34
• 页码：19729-19742
• 全文大小：705K
• ISSN：1932-7455

文摘

The present research focuses on the comparative investigation of the acid鈥揵ase surface properties (the isoelectric point, pH_iep and point of zero charge, pH_pzc) of one-dimensional TiO₂ nanomaterials. Different one-dimensional TiO₂ nanomaterials, nanotubes (NTs) and nanowires (NWs) were prepared by an alkaline hydrothermal synthesis procedure. The structural properties of the synthesized TiO₂ nanomaterials were investigated with high-resolution scanning electron microscopy (HR-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The NWs and NTs were characterized using Raman and Fourier transform infrared (FT-IR) spectroscopy as well as Brunauer鈥揈mmett鈥揟eller (BET) measurements. Surface properties, i.e. pH_iep and pH_pzc of NWs and NTs were determined from electrokinetic measurements, potentiometric mass and electrolyte titrations. The relative acidity for the NWs is found to be in the interval 3 < pH_iep < 4 in comparison with the NTs, with 4 < pH_iep < 6. The observed differences in the relative acidity are correlated with differences in crystal structure of the studied nanomaterials and their resulting morphology. In addition, our results reveal a strong electrolyte effect on the characteristic points, pH_iep and pH_pzc, especially the higher cation affinity for both TiO₂ nanomaterials surfaces that has a significant effect on the pH of the system. Application of the multisite complexation (MUSIC) model yields a satisfactory description of the electrokinetic data and can explain observed salt effect.