Shape and Morphology Effects on the Electronic Structure of TiO2 Nanostructures: From Nanocrystals to Nanorods

Nunzi, Francesca and Storchi, Loriano and Manca , Michele and Giannuzzi, Michele and Gigli, Giuseppe and De Angelis, Filippo (2014) Shape and Morphology Effects on the Electronic Structure of TiO2 Nanostructures: From Nanocrystals to Nanorods. ACS Appl. Mater. Interfaces, 6 (4). pp. 2471-2478. ISSN 1944-8244

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We carry out an accurate computational analysis on the nature and distribution of electronic trap states in shape-tailored anatase TiO2 structures, investigating the effect of the morphology on the electronic structure. Linear nanocrystal models up to 6 nm in length with various morphologies, reproducing both flattened and elongated rod-shaped TiO2 nanocrystals, have been investigated by DFT calculations, to clarify the effect of the crystal facet percentage on the nanocrystal electronic structure, with particular reference to the energetics and distribution of trap states. The calculated densities of states below the conduction band edge have been very well fitted assuming an exponential distribution of energies and have been correlated with experimental capacitance data. In good agreement with the experimental phenomenology our calculations show that elongated rod-shaped nanocrystals with higher values of the ratio between (100) and (101) facets exhibit a relatively deeper distribution of trap states. Our results point at the crucial role of the nanocrystal morphology on the trap state density, highlighting the importance of a balance between the low-energy (101) and high-energy (100)/(001) surface facets in individual TiO2 nanocrystals.

Item Type: Article
Additional Information: This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Appl. Mater. Interfaces, copyright © American Chemical Society after peer review and technical editing by the publisher.
Subjects: 500 Scienze naturali e Matematica > 540 Chimica e scienze connesse
Depositing User: Francesca Cavazzini
Date Deposited: 01 Sep 2014 12:43
Last Modified: 01 Sep 2014 12:43

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