Doctoral School ED548 University of Toulon

Supervisors : Christine Leroux and Madjid Arab

Co supervisor : Véronique Madigou

Team NSRE (NanoStructures Reactivity Environment ) IM2NP

1- Context

The growing interest of mankind in surrounding air quality leads to a growing need of precise gas concentration measurements, monitoring and cleaning of ambient air. However, existing devices are not satisfying in terms of efficiency/cost. Sensing materials should be selective et sensible to very low amount of polluting gas in air (from ppm to ppb, depending on the gas regulations). Nanoparticles are very reactive due to their large specific area but tend to agglomerate. Self- organized nanoparticles are expected to exhibit better sensibility and detection times than simple powders. Air depollution through light induced degradation of polluting gas is a new research field, and new materials which catalyse the photodegradation should be developed and characterized. Studies about the influence of the nano-structuration and self-organization of nanoparticles on the gas sensing properties, photo sensibility and photo degradation belong to the new topics in materials research science.

This research is part of an environmental approach, which aims not only to better control the amount of polluting gas in air (enhanced sensibility and selectivity, lowering of operating temperature,..) but also to clean ambient air through photo degradation of polluting gases. As such, this thesis fits perfectly in the frame of the research field of the University of Toulon entitled “Sea, Environment and Sustainable Development”.

Aim of the thesis :

• Synthesis of cobalt ferrites nanoparticules (1D)
• Elaboration of cobalt ferrite films (2D) by self-organization of nanoparticles on a substrat or incorporation in a flexible support and/or hierarchical structures (3D).
• Study of the detection and photocatalysis degradation performances

Au cours de cette thèse, le doctorant s’attachera à comprendre et à maîtriser les phénomènes à l'origine de la structuration et/ou hiérarchisation de nanoparticules ainsi que leur influence sur les performances des matériaux sensibles.

The PhD student will have to deal with improving the knowledge about the nano structuration /self-organization phenomena, as well as their influence of the photo catalytic and sensing properties.

2- Expected benefits

Economic and social benefits will be improvements in sensors efficiency for a better monitoring of ambient air, as well as in cleaning of ambient air through photocatalytic degradation of polluting gas, with a possible patent.

From the scientific point of view, we expect significative advances in the understanding of the influence of nano structuration in the solid gas interactions.

3- Means/partnerships

Technical means :

Elaboration and synthesis methods, transmission electron microscopy, X rays diffractometer, gas detection bench.

Partnerships :

This research subject will be developed in the frame of several partnerships :

national :

- Centre Interdisciplinaire de Nanosciences de Marseille (CiNaM) UMR CNRS 7325,

- Laboratoire de Physique des Solides d’Orsay

international :

- Université Fédérale Rio Grande do Norte (UFRN), Brésil

- Académie des Mines de Cracovie (AGH)

industrial :

- IMRA Europe Nice Sophia Antipolis.

Projet collaboration laboratoire MAPIEM Université de Toulon

4- PhD’s in the NSRE team related to the thesis topic : 

- Indira Fernandes de Medeiros, 2015-2018.

Cotutelle France UTLN-Brésil UFRN, (financement CAPES COFECUB)

Codirection Ch. Leroux et C. Pereira de Souza, co encadrement V. Madigou

Nanostructuration of cobalt ferrites Co_xFe_3-xO₄ : effects on catalysis and gas sensing.

- André Luis Lopes-Moriyama, 2012-2014.

Cotutelle France UTLN-Brésil UFRN, (financement CAPES COFECUB)

Codirection Ch. Leroux et C. Pereira de Souza, co encadrement V. Madigou

Elaboration of CoFe₂O₄  nanostructures and hierarchical powders; influence of the morphology on the detection and catalysed oxydation of polluting gases. .

- Lilia Ajroudi, 2008-2011.

Cotutelle France UTLN- Université de Tunis El Manar (financement CMCU)

Codirection Ch. Leroux et N. Thabet-Mikli.

Nanostructured cobalt ferrites ; elaboration, characterization, cataytic, electric and magnetic  properties

5- Publications of the NSRE team related to the thesis topic :

1- I. F. de Medeiros, V. Madigou, A. L. Lopes-Moriyama, C. Pereira de Souza, Ch. Leroux.

Synthesis of CoFe₂O₄ nanocubes

Nano-Structures & Nano-Objects 21 (2020) 100422. doi.org/10.1016/j.nanoso.2019.100422

2- I. F. de Medeiros, V. Madigou, A. L. Lopes-Moriyama, C. Pereira de Souza, Ch. Leroux.

Morphology and composition tailoring of Co_xFe_3-xO₄ nanoparticles

Journal of Nanoparticle Research, 20 (2018)1-12. doi: 10.1007/s11051-017-4097-y

3- A.  L.  Lopes-Moriyama, V.  Madigou, C.  Pereira de Souza, Ch.  Leroux

Controlled synthesis of CoFe₂0₄ nano-octahedra.

Powder Technology, 256 (2014) 482- 489. doi:  10.1016/j.powtec.2014.01.080

4- L. Ajroudi, N. Mliki, L. Bessais, V. Madigou, S. Villain, Ch. Leroux.

Magnetic, electric and thermal properties of cobalt ferrite nanoparticles.

Materials Research Bulletin, 59 (2014) 49-58.doi.org/10.1016/j.materresbull.2014.06.029

5- Ch. Leroux, M. Bendahan, V. Madigou, L. Ajroudi, N. Mliki

Nanoparticles of cobalt ferrite for NH₃ sensing

Sensors and transducers, vol. 27 (2014) 239-241,

6- L. Ajroudi, V. Madigou, S. Villain, N. Mliki, Ch. Leroux.

Potentiality of cobalt nanoferrites for gas sensors,

Sensor Letters, 9 (2011) 1-4.

7- L.  Ajroudi, V. Madigou, S. Villain, N.  Mliki, Ch.  Leroux,

Synthesis and microstructure of cobalt ferrite nanoparticles

Journal of Crystal Growth, 312 (2010) 2465-2471.