Page 1 of 55
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
The Journal of Physical Chemistry
An Experimental and Theoretical Approach to Understanding the Surface Properties of One‐Dimensional TiO2 Nanomaterials Atiđa Selmani,*, a Mario Špadina,a Milivoj Plodinec, b Ida Delač Marion,c Marc Georg Willinger,d Johannes Lützenkirchen,e Harry D. Gafneyf and Engelbert Redel**, g a
Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10002 Zagreb, Croatia; Tel: +385 (1) 4606130; E-mail:
[email protected],
[email protected] b
Department of Material Physics, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia; Tel: +385 (1) 456 1106, E-mail:
[email protected] c
Institute of Physics, Bijenička 46, Zagreb, Croatia, Tel: +385 (1) 469 8887; E-mail:
[email protected] d
Department of Inorganic Chemistry, Fritz Haber –Institute of the Max Planck Society, Faradayweg 4-6, D-14195 Berlin, Germany; Tel: +49 (30) 8413 4464; E-mail:
[email protected] e
Institut für Nukleare Entsorgung (INE), Karlsruher Institut für Technologie (KIT), Postfach 3640, 76021 Karlsruhe, Germany; Fax: 49 721 608-23927; Tel: +49 721 608-24023, E-mail:
[email protected] ACS Paragon Plus Environment
1
The Journal of Physical Chemistry
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
f
Page 2 of 55
Department of Chemistry, City University of New York, Queens College, Flushing, New York 11367, United States; Tel: 718 997 4114; E-mail:
[email protected] g
Karlsruhe Institute of Technology (KIT), Institute of Functional Interfaces (IFG), Hermann-
von-Helmholtz-Platz 1, D-76344, Eggenstein-Leopoldshafen, Germany; Tel: +49 (721) 608 24102; E-mail:
[email protected] ACS Paragon Plus Environment
2
Page 3 of 55
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
The Journal of Physical Chemistry
KEYWORDS: TiO2, one-dimensional TiO2 nanomaterials, nanowires (NWs), nanotubes (NTs), electrokinetic potential, surface charge, surface pH, surface reactivity/acidity, MUSIC model.
ABSTRACT
The present research focuses on the comparative investigation of the acid-base surface properties (the isoelectric point, pHiep and point of zero charge, pHpzc) 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-EmmettTeller (BET) measurements. Surface properties, i.e. pHiep and pHpzc 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 < pHiep < 4 in comparison with the NTs, with 4
