PhD subjects

For the analysis of a mixture of organic molecules in solution, Nuclear Magnetic Resonance (NMR) is, with mass spectrometry, one of the two most used analytical techniques. NMR is often considered to be more quantitative, more reproducible, and more able to identify a solute. However, it lacks sensitivity and resolution. The sensitivity can be increased by employing the particular properties of parahydrogen to create a so-called hyperpolarized state, which transiently but considerably increases the NMR signal. Regarding resolution, it can be notably improved by the use of multidimensional NMR spectroscopy, which should be fast in the case of the analysis of hyperpolarized species. Liquid-liquid extraction, a very frequently used separation process, involves two immiscible phases in which the solutes are distributed according to their affinity. Provided it is fast enough, it allows specific observation of hyperpolarized solutes in each phase, as shown in a preliminary study for a chloroform/water system. The aim of this thesis project is to develop this approach combining hyperpolarization by parahydrogen and extraction, to extend it to new biphasic systems and to apply it to the detection, identification and quantification of very dilute solutes. The ultimate goal is to apply this methodology to samples that contain in essence many solutes, such as those from synthetic chemistry or metabolomics.

The objective of this Phd is to develop an experimental device to perform in situ and real time elemental analysis of nanoparticles during their synthesis (by laser pyrolysis or flame spray pyrolysis). Laser-Induced Breakdown Spectroscopy (LIBS) will be used to identify the different elements present and their stoichiometry.



Preliminary experiments conducted at LEDNA have shown the feasibility of such a project and in particular the acquisition of a LIBS spectrum of a single nanoparticle. Nevertheless, the experimental device must be developed and improved in order to obtain a better signal to noise ratio, to increase the detection limit, to take into account the different effects on the spectrum (effect of nanoparticle size, complex composition or structure), to automatically identify and quantify the elements present.



In parallel, other information can be sought (via other optical techniques) such as the density of nanoparticles, the size or shape distribution.

The industrial synthesis of chemical products is currently based on the oxidation of fossil compounds. In the current context of energy transition and reduction of the dependence on petroleum products, new ways of carbon sources must be used to maintain the production of these compounds essential to our societies. CO2 is a good candidate, but is not very reactive. Its conversion into CO, coupled with the production of H2 by electrolysis, allows the formation of syngas (CO:H2 mixture) which is a reactive gas allowing the synthesis of numerous chemical products, among others thanks to the Fisher-Tropsch process.



We propose in this thesis project to design new catalysts for the synthesis of alkylamines by Fisher-Tropsch reaction on amines, using syngas from renewable sources. The PhD student will search for new catalysts, optimize them, testing them in the Fisher-Tropsch reaction on amines. The objective will be to have a catalyst that is efficient, selective, and not very sensitive to contaminants such as O2 or H2O. Once this system is optimized, the catalyst will be tested in devices to be designed and built, allowing the use of real syngas supplied by other groups at CEA, formed by gasification of biomass for example.

Graphene as a constituent of graphite was close to us for almost 500 years. However, it is only in 2005 that A. Geim and K. Novoselov (Nobel Prize in 2010) reported for the first time the obtaining of a nanostructure composed by a single layer of carbon atom. The exceptional electronic properties of graphene make it a very promising material for applications in electronic and renewable energies.



For many applications, one should be able to modify and control precisely the electronic properties of graphene. In this context, we propose to synthesize chemically graphene nanoparticles and study their absorption and photoluminescence properties. This project will be developed in collaboration with Physicists so the candidate will work in a multidisciplinary environment.

The aim of this project is the synthesis of new molecular structures based on porphyrins for the formation of 0D, 1D and 2D nanostructures. Porphyrins are an important class of molecules that are essential to life through oxygen transport or photosynthesis. Beyond, their importance in Nature, porphyrin derivatives exhibit outstanding optical, electronic, chemical and electrochemical properties that make them promising candidates for applications in catalysis, electrocatalysis, optoelectronics and medicine.



In this project, the porphyrins will be studied in collaboration with several groups of Physicists in order to fabricate 1D or 2D covalent networks on surface via the "bottom-up" approach and to study their electronic and optical properties.

Recycling the 460 million tons of plastics produced each year is a major environmental and energy challenge of the 21st century. The use of recycled plastics is an important lever for reducing the overall CO2 emissions associated with the production and processing of new plastics. However, our ability to recycle plastics remains severely limited by the appearance of new chemical compounds during the aging of the materials to be recycled. In this thesis, we propose to study the aging of plastic additives by combining a historical study and an experimental approach. In a first approach, we will document the compositions and transformation processes of plastics from 1950 onwards, and, from dated samples, the new compounds formed during aging. In a second approach, we will simulate the aging processes by controlled irradiation, in order to reconstitute the reaction chains. The products of natural and artificial aging will be studied in terms of toxicity.

Hydrogen is an excellent energy storage medium, especially in the context of an energy transition based on intermittent renewable energies. However, the problem of its storage and transport arises. Several technologies are currently being explored and the storage of hydrogen in solid materials is an option that has several advantages. Borohydrides, in particular those of alkaline metals, are stable solid materials allowing to store a significant quantity of hydrogen in mass proportion (19 wtH2% for LiBH4, 10 wtH2% for NaBH4). However, their use is still limited because of the very energy consuming synthesis and recycling.



We propose in this project to develop new methodologies to generate boron hydrides from hydrogen in order to immobilize the latter in solid materials for energy storage purposes. The transformation of B-X (X:O,Cl) bonds to their B-H equivalents is a real challenge due to the high affinity of boron with oxygen and the high hydricity of the target compounds which make them reactive hydride donors. Similar work has been described at the LCMCE and by other groups for the synthesis of hydrosilanes and relies on transition metal catalysts or boron-based organocatalysts.



This project will allow the PhD student to develop advanced skills in homogeneous catalysis, characterization of molecular complexes, and gas manipulation.



Translated with www.DeepL.com/Translator (free version)

Single-atom catalysts (SAC) are solid catalysts in which all the active metal atoms are isolated and stabilized on a support, or by an alloy with another metal. The activity is carried by isolated metal atoms, their selectivity is therefore excellent, and the qualities of SACs approach those of homogeneous catalysts while offering the advantages of robustness and ease of handling of solid catalysts. SACs, which allow a high economy of catalytic metals, are good candidates for the implementation of transformations promoting the circular carbon economy and the storage of energy by the hydrogen vector. In particular, they can play an important role for CO2 hydrogenation as well as for hydrogenation and dehydrogenation reactions of liquid organic hydrogen carriers (LOHC), which are an essential element for the transport and storage of energy by the hydrogen vector. However, they remain rather poorly described for these transformations, and the existing examples mostly involve noble metals (Pd, Pt, Au).

The objective of this thesis is twofold. On one hand, it aims at synthesizing and characterizing innovative isolated atom catalysts based on non-noble metals (Ru, Fe, Mn, Co, Cu) capable of catalyzing the reversible hydrogenation of C=O bonds in CO2 and the dehydrogenative coupling of alcohols with water and of alcohols between them. On the other hand, it aims at exploring the possibilities of systems based on alcohol + water/carboxylic acids as LOHC.

The work will consist in synthesizing, characterizing and testing the catalytic activity of different single atom catalysts. The student will be trained in the techniques of synthesis under inert atmosphere, catalysis in pressurized reactors, as well as in the use of various analytical techniques: SEM, HR-TEM, HAADF-TEM, EDX, XPS, XRD

To successfully enter the photovoltaic market, perovskite solar cells are still facing several tough challenges. Scalability of the processes and stability of the devices need to be ensured. The latter especially has been one of the main causes of skepticism for a long time and is still underestimated in most studies.



Outdoor operational conditions are rarely considered and only few reports can be found. All reports show that, as testing time increase, devices suffer both reversible and more importantly irreversible degradations, which potentially are not detected in a constant temperature, constant one-sun irradiance Maximum Power Point (MPP) tracking procedure, confirming the necessity for outdoor testing under real operational conditions.



This thesis relies on : design, fabrication and characterization of devices to be placed on outdoor test bench for testing under operational conditions.

In today's energy mix, gas is an immediately available, storable energy that is supported by a very large distribution network. It is possible to completely replace fossil gas with 100% renewable gas by 2050. However, the quality of biogas is much more fluctuating than that of fossil gases and "power to gas". Radiolysis (degradation by ionising radiation) of impurities could be a method of choice to carry out this purification in a simple way, or even to propose alternative storage methods by functionalising the biomethane.

Using a mixture of cells isolated from an animal tumor that has been injected with a radiolabelled anti-cancer drug, we propose to quantify the exact dose of the drug accumulated in each cell of the tumor. Such an approach will make it possible to answer an essential question in pharmacology: to relate the observed effects (therapeutic and undesirable) to the dose of the drug delivered, in this case at the level of the single cell (cancer cells), but also all the other cell types present in the tumor tissue. We will build on our recent developments in antibody and molecular radiolabelling, cells capture on microfluidic devices and beta-imaging.

Background: This project follows a work supported by the Foundation for Medical Research (2018-2022) where we showed the relevance

of modifying the surface of platinum coils (intracranial implants used to treat aneurysms) in order to accelerate aneurysmal healing. This

was demonstrated in vivo by covalent grafting of a polysaccharide, fucoidane, on the surface of the coils.



Objectives of the thesis

The objectives of the thesis project are the following:

1- Optimize the coating of coils allowing a development under GMP (Good Manufacturing Practices) conditions and adapt the method to

an industrial process.

2- To fully characterize the coating in terms of density, thickness and regularity using physicochemical techniques (ATG, DSC, contact

angle, elemental analysis) and optical imaging (biphotonic imaging, scanning electron microscopy, AFM) and spectroscopic techniques

(EDS, XPS).

3- To validate the conditions retained by implantation of the modified coils in a rabbit aneurysmal model.

Partners: UMR NIMBE LICSEN, BALT Company, LVTS Inserm U1148 and XLIM UMR CNRS 7252, CHU Limoges.

The large-scale use of proton exchange membrane fuel cells (PEMFCs) for vehicle engines requires the development of new catalysts. Indeed, the high costs of PEMFCs are mainly linked to the use of a large amount of a noble metal, the platinum, as a catalyst for electrochemical reactions in order to obtain sufficient performance. This Ph.D work deals with the synthesis and the optimization of new catalysts having only a small amount of Pt supported on a carbonaceous material also exhibiting catalytic activity toward the reduction of oxygen. These nitrogen-enriched support carbons comprising a non-noble metal associated with a tiny amount of Platinum should ultimately lead to inexpensive materials. The objective of the Ph.D work is therefore to synthesize and optimize on a large scale carbonaceous catalytic supports and to quantify the number of active sites for the manufacture of catalysts with low platinum loading.

Catalysis is today at the core of chemical industrial applications. For example, the conversion of nitrile to amide, which is relevant in pharmaceuticals, agrochemicals, synthetic chemistry and polymer chemistry, by hydration requires an efficient catalyst due to its slow kinetics. For environmental reasons, it is crucial to discover catalysts without transition metals, neither toxic nor corrosive, and cheap. One example of such catalyst is hydroxide choline.



During this thesis, the student will learn how to perform ab initio molecular dynamics simulations coupled with a method which can reconstruct the free-energy landscape of the hydration reaction for different aromatic nitriles in different in silico experimental conditions. He or she will also have to perform quantum chemistry calculations at a level that can describe all the required intra and intermolecular interactions. This theoretical approach has already been successfully used within our team to describe other chemical reactions in aqueous solution and will be applied to the innovative field of green chemistry.

Lithium-ion batteries, widely present in our daily lives, have revolutionized portable applications and are now used in electric vehicles. However, the development of new generations of batteries for future applications in transport and storing electricity from renewable sources is vital to mitigating climate change.



Sodium is more abundant on earth than lithium and therefore attractive in particular for large-scale stationary storage applications. Lithium-ion technology is generally considered as the preferred solution for applications requiring high energy density, while sodium-ion technology is particularly attractive for applications requiring power.

However, liquid electrolyte batteries present environmental risks such as leaks and can occasionally experience safety problems. Faced with the requirements concerning the environment and safety, solid-state batteries based on solid electrolytes can provide an effective solution while meeting battery energy storage needs. The barriers to overcome allowing the development of all-solid-state battery technology consist mainly in the research of new chemically stable solid electrolytes with good electrical, electrochemical and mechanical performance. For this goal, this thesis project aims to develop “ceramic / polymer” composite solid electrolytes with high performance and enhanced safety. Characterizations by electrochemical impedance spectroscopy (EIS) will be carried out in order to understand the cation dynamics (by Li+ or Na+) at the macroscopic scale in composite electrolytes, while the local dynamics will be probed using advanced techniques of Solid state NMR (23Na / 7Li relaxation, 2D NMR, in-situ NMR & operando). Other characterization techniques such as X-ray and neutron diffraction, XPS, chronoamperometry, GITT ... will be implemented for a perfect understanding of the structure of electrolytes as well as aging mechanisms at the electrolyte / electrolyte and electrolyte/electrode interfaces of the all-solid battery.



Key words: composite solid electrolyte, all-solid-state battery, interfaces, multiscale characterization, dynamics of Li + and Na + ions, electrochemical performance, solid-state NMR, X-ray / neutron diffraction.

The project is experimental and focuses on the study of new families of polyelectrolytes (PE) by determining their phase diagrams as a function of variations in temperature, added salt or pH. This will be done optically (microscopy, diffusion) at CEA Saclay. Once the diagrams have been established, the phase separation (PS) of the PE solutions will be studied by confocal fluorescence microscopy to determine the growth laws and the scaling behavior of the separation. Phase separation is a dynamic process that will be initiated by temperature or concentration quenches, followed by the acquisition of time series images or correlation functions. It will lead to the formation of spatial structures that will be used to achieve an interconnected porous geometry. The results will be translated into guidelines for membrane manufacturing procedures that will be applied in Montpellier (European Institute of Membranes) to manufacture porous polyimide membranes of high mechanical and thermal resistance. Another side of the project will be to reproduce the experimental finding by a theoretical model able 1/ to explain the measured phase diagrams, 2/ to complete existing phase field theories for phase separation of neutral polymers to describe PE phase separation.

Giving a general view of the colloidal stability of nanoparticles in a biological environment remains difficult. This comes mainly from the complexity of biological environments and the diversity of nanoparticles in terms of size distribution, shape, nature of external surface and nanostructure. In particular, the number of physico-chemical studies on “soft” organic particles obtained by self-assembly of bioconjugates remains low. To understand how the physico-chemical characteristics of "soft" nanoparticles direct their interactions with blood proteins, we propose, in collaboration with the Institut Galien, to study a concrete case where the nanostructure and the surface charge of the nanoparticles give different pharmacologically efficiency (analgesic). The objective is to study in detail how nanoparticles formed by self-assembly of bioconjugates interact with a model biological medium, taking into account both the main components (albumin, hemoglobin and lipoproteins) and the hydrodynamic flow from the circulation blood.

Diamond nanoparticles behave outstanding chemical, electronic, thermal and optical properties. Such nanoparticles are actively investigated for nanomedecine, energy applications, quantum technologies and advanced lubricants and composites [1-3]. For the major part of these applications, the crystalline quality of the diamond core is essential and the most studied particles are milled from bulk diamond. Nevertheless, these particles exhibit a wide size dispersion, shape anisotropies and variable concentrations of chemical impurities. These aspects strongly affect their properties. It is thus required to develop a synthesis method to grow highly crystalline nanodiamonds with an accurate control of their size, morphology and chemical impurities.

This PhD aims to develop a bottom-up synthesis based on sacrificial templates (silica beads or fibers) on which nanometric diamond seeds will be attached via electrostatic interactions. Diamond growth will be achieved by an exposure of the seeded templates to a micro-wave assisted CVD plasma (MPCVD). The growth set-up is already in use at CEA NIMBE for diamond core-shells synthesis [4]. Growth parameters will be adjusted to select the size, the shape and the concentration of chemical impurities (nitrogen, boron) in nanodiamonds. After CVD growth, nanoparticles will be collected by dissolution of the templates. Their crystalline structure, morphology and surface chemistry will be characterized at CEA NIMBE by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman, infra-red (FTIR) and photoelectrons (XPS) spectroscopies. An external collaboration will allow an investigation of the diamond crystalline quality and the identification of structural defects in CVD grown nanodiamonds by high-resolution transmission electron microscopy (HR-TEM).

Several kinds of nanodiamonds will be grown : first, intrinsic particles (without intentional doping), then boron doped particles. Both types of particles will be then surface modified to get a colloidal stability in water. Photocatalytic performances will be measured in collaboration with ICPEES (Strasbourg University). This original synthesis method will also permit to create colored centers (nitrogen-vacancy or silicon-vacancy) in nanodiamonds to exploit their optical properties (collaboration to initiate).



Références :



[1] N. Nunn, M. Torelli, G. McGuire, O. Shenderova, Current Opinion in Solid State and Materials Science, 21 (2017) 1-9.

[2] Y. Wu, F. Jelezko, M. Plenio,T. Weil, Angew. Chem. Int. Ed. 55 (2016) 6586–6598.

[3] H. Wang, Y. Cui, Energy Applications 1 (2019) 13-18.

[4] A. Venerosy et al., Diam. Relat. Mater. 89 (2018) 122-131.

The proof of concept of the effectiveness of sol-gel coatings doped with carboxylic acid for the protection of copper-bearing heritage metals was demonstrated in a first PhD-thesis conducted within a NIMBE LAPA/LEDNA collaboration. In order to optimise the formulation of this coating on metals with a Corrosion Product Layer (CPL) of several tens of micrometres thickness that needs to be preserved, it is necessary to develop an in-depth study of the physico-chemical mechanisms of the protection. In this new thesis project, a multi-technique and multi-scale characterisation methodology will be implemented on old CPC samples as well as on model CPC samples. On the one hand, the formulation parameters (TMOS and/or TEOS precursors) will be adjusted to favour brush or spray application. On the other hand, the protection mechanisms will be studied through electrochemical measurements as well as through re-corrosion experiments in marked media (D2O/18O2, KBr under aggressive immersed conditions). The analytical protocol will be based on analyses at the global scale (viscosity, BET, mercury porosimetry, ATG, DRX), at the micrometric scale (SEM-EDS, Raman spectrometry) as well as at the nanometric scale (TEM on FIB slides) in order to understand the systems obtained during the treatments.

One of the ways strongly encouraged by the IPCC (Intergovernmental Panel on Climate Change) to mitigate climate change is the capture of CO2 by liquid amines, followed by the recovery of the gas and its deep underground storage. However, an essential problem makes the process currently inefficient: the recovery of CO2 must be done by heating and is too energy intensive.



In this context, this thesis will study how the addition of nanoparticles improves the recovery of CO2 from liquid amines. These “nanofluids” have proven efficacy, but there is little guidance on how to achieve an appropriate composition, and no consensus on the mechanism that would facilitate the release of CO2 gas.



The objective of this thesis is to propose rational guidelines, which will lead to the best nanoparticle + liquid amine combination, replacing the current trial-and-error approaches. It will therefore be necessary to study how the surface of nanoparticles 1) activates the chemical reaction of release, and 2) facilitates the physical process of nucleation of gas bubbles.

This PhD subject is focused on evaluating novel cement and mortar formulations comprising repurposed industrial slags, ashes, and lightly-processed raw minerals as more sustainable alternatives to Ordinary Portland Cement (OPC). These formulations will be optimized to facilitate the setting and strengthening of concrete via carbonation rather than hydration, which has the potential to reduce even further the emissions of concrete towards net carbon capture and storage (CCS). The carbonation mechanisms of the different formulations under different environmental conditions (temperature, relative humidity, %CO2) will be elucidated in situ using a variety of techniques including micro X-ray diffraction (XRD) and X-ray micro computed tomography (µ-CT). We will also further develop recently-introduced methods in digital pH imaging to understand the evolving chemical environment in and around the cement as it matures. Cement and mortar formulations will be characterized across a number of length and time scales utilizing microfluidic devices up to full-scale carbonation cabinets and utilizing laboratory X-ray sources up to synchrotron radiation facilities.

H2 is a promising vector for solar fuels due to its high energetic content (142 kJ/mol) compared to fossil fuels. Efficient technologies for H2 production are still under investigation and storage and transportation need to be addressed.

This PhD aims to elaborate hybrids from ND and TiO2 toward H2 production by photoassisted water splitting under solar-light, following two different strategies: (i) by electrostatic adsorption (layer-by-layer approach) of the different ND and TiO2 materials dispersed in suspension; (ii) by introducing ND during the synthesis of TiO2 nanostructures. Post-synthesis treatments such as annealing in controlled atmospheres will also be considered to favor optimized TiO2/ND interfaces. ND of different crystalline quality (detonation, HPHT milled), shape (rounded, facetted) and size (from 5 to 150 nm) will be prepared with adequate surface chemistries (C-H, C-NH2, sp3/sp2) at CEA by well-established gas-phase annealing methods (under H2, NH3 or vacuum). ICPEES will provide TiO2 nanostructures of different crystalline structure (rutile/anatase), crystalline quality, morphology (nanoparticles, nanotubes) and size using tunable sol-gel and hydrothermal synthesis approach. The effect of surface pre-treatments on TiO2 PC efficiency will be investigated. The various photocatalysts will be characterized all along its development by SEM, HRTEM, XPS, FTIR, XRD, Raman. Then, performances of ND/TiO2 catalytic materials for H2 production by PC will be quantified at ICPEES by means of assessment of photocatalytic water-splitting under solar and visible light irradiation. Kinetics of H2 production will be followed as well as determination of quantum yields will be studied depending as a function of concentration of photocatalyst, nature and concentration of sacrificial agent and light irradiance.

This thesis work focuses on the development of a new microporous structure for PEMFC gas diffusion layers. The development of new materials for PEM fuel cells is a necessity to improve the power density provided by actual cell, to reduce the cost of materials and the price of the system. PEMFCs have problems with the distribution of liquid water inside the cell, particularly in its porous

layers. The microporous layer is one of the porous layers whose role is to optimize the water distribution. Developing a new micro-porous structure can provide additional information on the parameters influencing water management in the cell and provide a path to improving the fuel cell performance. As part of the PEPR (Priority Research Program and Equipment) H2 PEMFC95 project, the CEA Departments of IRAMIS (Saclay) and Hydrogen for Transport (LITEN-DEHT Grenoble) will collaborate on the development of Optimized and innovative GDLs based on carbon nanotubes, more suitable for the defined operating conditions. Aligned CNT mats have indeed demonstrated their effectiveness as a microporous layer [1]. The performance is at least similar to the best state-of-the-art gas diffusion layer depending on the conditions, and up to 30% improvement in power density could be achieved, without any hydrophobic treatment. For this thesis subject, we propose to continue the development of these diffusion layers integrating CNTs for their interest in terms of stability with respect to oxidation and their hydrophobicity by producing microporous layers with variable porosity. The objective is to substitute them for GDL while improving understanding of its role and, in general, of transport phenomena in a PEMFC core. To do this, the work has two parts. A materials section with manufacturing aspects and characterization of functional properties and an electrochemistry section with fuel cell measurements

In the context of the energy transition, the production of hydrogen from solar energy appears to be an extremely promising means of storing and then producing energy. The photoelectrolysis of water, to develop on a large scale, needs materials with high catalytic efficiency. Among the candidates considered, materials derived from barium titanates appear promising because their ferro- and piezoelectric properties could increase their photocatalytic effect.



We therefore propose in this subject, carried out in collaboration between the LEEL of the CEA and the SPMS of Centrale – Supelec, to synthesize BaTiO3 nanoparticles by flame spray pyrolysis with substitutions on Ba and O in order to study the effect of these modifications on the ferroelectric properties of the material. The addition of noble metal inclusions on the surface of the particles, likely to improve the catalysis, will also be carried out during the synthesis of the latter. Finally, photocatalysis and piezocatalysis tests will make it possible to establish the links between ferroelectric and catalytic phenomena in this family of materials.