Reference : UMR8234-EMMDUB-002
Nombre de Postes : 1
Workplace : PARIS 05
Date of publication : Friday, January 20, 2023
Scientific Responsible name : Emmanuelle Dubois
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 April 2023
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Within the general context of energetic transition, one possibility to increase the generation of electrical energy is to convert thermal (waste) energy into electricity. For this purpose, a carefully designed thermoelectric material is introduced between two electrodes maintained at different temperatures. The thermal gradient generates a difference of electrical potential.
This PhD is part of an ANR project called WH-RECOLTE, involving 3 labs (SPEC/CEA, IFJC lab and Phenix), that aims at unraveling some underlying mechanisms of this energy conversion and to correlate the molecular behavior to macroscopic quantities (tension, power output…) with the long-term goal to improve the thermoelectric properties and demonstrate the potential of this technology.
The thermoelectric material studied here is a liquid dispersion of nanoparticles in solvents based on ionic liquid, comprising a redox couple for electron transfer . The formulation of such a complex liquid, which is unconventional and new, enables the use of abundant and non-critical elements, a high versatility in shape and possible up-scaling. Such dispersions have proven interesting properties compared to solid materials, as shown in previous ANR or European projects implying two of the partners of this new project (see  and https://www.magenta-h2020.eu/ ). However, many challenges remain, as the understanding and the improvement of the redox species performances, their interaction with the nanoparticles, the interaction between the particles and the solid electrodes, the role of the nature of the particles… This knowledge will enable the optimization of the composition of the dispersion (nanoparticles, carrier fluid, redox couple) to reach the expected energy conversion.
Within this project, PHENIX is implied in the dispersion of nanoparticles in solvents with added redox species and in the study of their properties, here the colloidal structure in the long run and the thermodiffusion properties. These studies have to be done in strong interaction with the other partners, in charge with the thermoelectric measurements (SPEC/CEA) and with the redox species design (IJC lab).
The PhD student enrolled in the PHENIX lab will be strongly involved in the thermodiffusion measurements (i.e., the diffusion of particles under a gradient of temperature) and determination of the related Ludwig Soret coefficient: this coefficient is closely related to the thermoelectric performances of the material. Thermodiffusion is measured with a homemade Rayleigh Forced scattering instrument thermalized up to 200°C [3,4]. The PhD student will need to develop new types of measurements for non-absorbing nanoparticles. He/she will also be involved in the study of the colloidal structure versus temperature and over time using for example Dynamic Light Scattering (DLS) and Small Angle X-Ray Scattering (SAXS). He/she will need to closely interact with the colleagues who produce the dispersions in PHENIX and with the members of the other ANR partners.
 Riedl, J. C.; Sarkar, M.; Fiuza, T.; Cousin, F.; Depeyrot, J.; Dubois, E.; Mériguet, G.; Perzynski, R.; Peyre, V. Design of Concentrated Colloidal Dispersions of Iron Oxide Nanoparticles in Ionic Liquids: Structure and Thermal Stability from 25 to 200 °C. J. Colloid and Interface Science 2022, 607, 584–594.
available on chemrxiv:
 2- K. Bhattacharya, M. Sarkar, T. J. Salez, S. Nakamae, G. Demouchy, F. Cousin, E. Dubois, L. Michot, R. Perzynski, and V. Peyre, “Structural Thermodiffusive and Thermoelectric Properties of Maghemite Nanoparticles Dispersed in Ethylammonium Nitrate
ChemEngineering, vol. 4, p. 5, 2020 https://www.mdpi.com/2305-7084/4/1/5
 M. Sarkar, J.C. Riedl, G. Demouchy, F. Gélébart, G. Mériguet, V. Peyre, E. Dubois, and R. Perzynski," Inversion of thermodiffusive properties of ionic colloidal dispersions in water-DMSO mixtures probed by forced Rayleigh scattering" , Eur. Phys. J. E (2019) 42: 72
 T. Fiuza, M. Sarkar, J. C. Riedl, A. Cebers, F. Cousin, G. Demouchy, J. Depeyrot, E. Dubois, F. Gelebart, G. Meriguet, R. Perzynski, V. Peyre, Thermodiffusion anisotropy under a magnetic field in ionic liquid-based ferrofluids, Soft Matter, 2021, 17, 4566
Expected skills for the PhD candidate:
- Physics with good chemistry notions or chemical physics background
- Interest for experiments, instrumentation (optics, physics, electronics…) and modelling
- Communication abilities with other communities (chemists, …)
- English mandatory, French is a plus
Phenix is an interdisciplinary laboratory of Sorbonne Université where physicists and chemists work together, combining experimental and theoretical approaches to improve fundamental knowledge on various topics around charged interfaces, keeping in mind the current challenges around energy, health or environment (45 permanent staff / 45 non permanent staff).
The PhD student will be particularly involved in two teams: the “Inorganic colloids” team, specialized in synthesis, stabilization and characterization of nanoparticles in various complex fluids such as organic solvents, ionic liquids or mixtures of solvents; the “Modelisation and Multiscale Experiments” team, which focuses on the dynamics and transport in complex systems at different scales.
Researchers involved in the project: Véronique Peyre, Gilles Demouchy, Guillaume Mériguet, Régine Perzynski
https://phenix.cnrs.fr/en/home/ (website under migration)
Localisation : 4, place Jussieu – 75005 Paris – France
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