Nanostructuration modeling for optimization of energy conversion and storage in heterogeeous TiO2 naotubes

Directeur de thèse : Pr. Said Ahzi

Unité d’Accueil : UMR 7357 - ICUBE
Laboratoire des Sciences de l'Ingénieur, de l'Informatique et de l'Imagerie
Département de mécanique
Equipe : Matériaux Multiéchelle et Biomécanique

Établissement de rattachement: UdS

Collaboration : Prof. Garmestani, George Instiutute of Technology, MSE, Atlanta, USA; et Dr. A. Slaoui, ICube

Descriptif du sujet :
Heterogeneous nanostructures such as coaxial nanotubes, nanowires and nanorods have been of growing interest due to their potential for high energy-conversion efficiencies and charge/discharge rates in solar cell, energy storage and fuel cell applications. Their superior properties at the nanoscale as well as the high surface areas, fast charge transport along large interfacial contact areas, and short charge diffusion lengths has made them be considered as attractive components of next generation high efficiency energy-conversion devices.
Vertically-oriented TiO2 nanotube arrays are considered as a robust and cost-effective nanostructure for a wide range of applications particularly those related to energy conversion such as solar hydrogen generation. Despite its fascinating properties, one major challenge limiting the use of such material for solar-irradiation driven applications involves with its electronic structure, namely, the large bandgap and improper band-edge positions with respect to photocatalytic reactions. Therefore, intense effort has been invested on modifying the electronic properties of TiO2 by band-gap engineering via two active approaches, doping the bulk structure, or by suitable surface modification of the TiO2 via sensitization or heterojunction formation to create a visible-light response. Despite significant enhancement obtained in the efficiency of photoconversion in many doped TiO2 systems, an important question is still remained which involves with identification of whether the nanocrystals have been successfully doped and whether the microstructure is optimal.
Here we focus on these newly developed Sr doped TiO2 nanotube arrays with application to photoconversion and to micro solid oxide fuel cells. We propose to develop a multiscale approach for simulate the growth of these nanostructures and the effects of Sr doping. The goal of the proposed work is to use the developed multiscale model and associated simulation results to optimize the microstructure and doping for the best efficiency of energy-conversion devices with application to photovoltaics and also to the design of electrolytes of solid oxide fuel cells.

Contexte :
A first work as been conducted as a part of the PhD thesis of Hoda Amani-Hamedani at Georgia Tech. (Atlanta), under the supervision of Prof. H. Garmestani. This first work was fully experimental and involved collaboration with Prof. Ahzi (ICube). We plan to develop this work further and propose a robust numerical tool that will be used guide the fabrication of efficient energy conversion devices. This project will involve a strong collaboration with Prof. H. Garmestani at Georgia Tech.-Atlanta and also with the team of Dr. A. Slaoui at ICube.