DFT makes the morphologies of anatase-TiO2 nanoparticles visible to IR spectroscopy
Résumé
We use a multitechnique approach to reveal how the nature and concn. of surface acid-basic OH groups present on anatase-TiO2 nanocrystallites depend on their morphologies. Coupling recent d. functional theory (DFT) calcns. with three phys. characterization techniques (X-ray diffraction, transmission electron microscopy, and Fourier transform IR spectroscopy), the different IR (IR) spectroscopic properties of two anatase samples are explained by morphol. 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 calcns., the assignment of the OH stretching bands depends on the surfaces exposed by the anatase-TiO2 nanocrystallites. The signature of the nanocrystallites morphol. can thus be captured by IR spectroscopy.