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Using Density Functional Theory to Model Realistic TiO2 Nanoparticles, Their Photoactivation and Interaction with Water

Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via R. Cozzi 55, 20125 Milano, Italy
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Catalysts 2017, 7(12), 357; https://doi.org/10.3390/catal7120357
Received: 16 October 2017 / Revised: 8 November 2017 / Accepted: 20 November 2017 / Published: 24 November 2017
(This article belongs to the Special Issue Titanium Dioxide Photocatalysis)
Computational modeling of titanium dioxide nanoparticles of realistic size is extremely relevant for the direct comparison with experiments but it is also a rather demanding task. We have recently worked on a multistep/scale procedure to obtain global optimized minimum structures for chemically stable spherical titania nanoparticles of increasing size, with diameter from 1.5 nm (~300 atoms) to 4.4 nm (~4000 atoms). We use first self-consistent-charge density functional tight-binding (SCC-DFTB) methodology to perform thermal annealing simulations to obtain globally optimized structures and then hybrid density functional theory (DFT) to refine them and to achieve high accuracy in the description of structural and electronic properties. This allows also to assess SCC-DFTB performance in comparison with DFT(B3LYP) results. As a further step, we investigate photoexcitation and photoemission processes involving electron/hole pair formation, separation, trapping and recombination in the nanosphere of medium size by hybrid DFT. Finally, we show how a recently defined new set of parameters for SCC-DFTB allows for a proper description of titania/water multilayers interface, which paves the way for modeling large realistic nanoparticles in aqueous environment. View Full-Text
Keywords: nanospheres; simulated Extended X-ray Adsorption Fine-Structure (EXAFS); excitons; trapping; titania/water interface; SCC-DFTB; B3LYP nanospheres; simulated Extended X-ray Adsorption Fine-Structure (EXAFS); excitons; trapping; titania/water interface; SCC-DFTB; B3LYP
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Selli, D.; Fazio, G.; Di Valentin, C. Using Density Functional Theory to Model Realistic TiO2 Nanoparticles, Their Photoactivation and Interaction with Water. Catalysts 2017, 7, 357.

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