DFT makes the morphologies of anatase-TiO2 nanoparticles visible to IR spectroscopy

We use a multitechnique approach to reveal how the nature and concentration of surface acid-basic OH groups present on anatase-TiO2 nanocrystallites depend on their morphologies. Coupling recent density functional theory (DFT) calculations with three physical characterization techniques (X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy), the different infrared (IR) spectroscopic properties of two anatase samples are explained by morphology effects resulting from the synthesis pathways. Whereas a conventional route leads to anisotropic shapes, the multigelation method leads to more '' spherical '' shapes. As shown by the DFT calculations, the assignment of the OH stretching bands depends on the surfaces exposed by the anatase-TiO2? nanocrystallites. The signature of the nanocrystallites morphology can thus be captured by IR spectroscopy. (c) 2005 Elsevier Inc. All rights reserved.