Solid Oxide Fuel/Electrolysis Cells are electrochemical devices based on ceramics which operate at high temperature, typically 600-800 °C. This high temperature is needed to ensure fast diffusion and reaction rates i.e. to allow for high power efficiency. Unfortunately, coupled with extreme operating conditions, high working temperatures lead to fast degradation. Materials discovery efforts have thus targeted new electrolyte and electrode materials with improved ionic and/or electronic conductivity and electrochemical activity, able to operate at a lower temperature. Other strategies concerned the development of new types of solid oxide cells, based on new charge carriers. Among these, Proton Conducting Cells, which can operate at a temperature below 600°C, are particularly promising. With typical performances of 0.3 W/cm2 at 600 °C in 2013, they can now reach 1.3 W/cm2 at 600 °C as reported in 2018. This is an increase of more than 300% in five years, which represents a significant acceleration. To achieve such a performance, materials have been designed with complex compositions having typically 4-5 different cations, whose relative ratios were determined empirically. Still, the exploration of new or optimized compositions remains limited by the highly time-consuming tasks to fully characterize such materials. Thus, in the highly competitive international context of cells development and fabrication, new approaches allowing a fast screening of many compositions might constitute an efficient strategy to fasten the development of high-performing cells. The objective of AutoMat-ProCells project is precisely to combine advanced research tools for screening efficiently the intrinsic properties of oxide materials for proton-conducting oxide cells. It is based on a high-throughput experimental approach. More concretely, our project couples the development of combinatorial deposition for the preparation of materials library bu pulse laser deposition, their exhaustive structural/chemical characterization in a highly efficient way including synchrotron-based techniques, and the measurement of electrolyte/electrode properties through electrical, isotope exchange and nuclear probe measurements. From this, we will obtain unique information on structure, stability, hydration, conductivity, electrochemical activity, the kinetics of ionic species transfer and diffusion, this for an extensive range of compositions. Through AutoMat-ProCells, we will also pave the path toward a renewed strategy for a very efficient exploration of materials for SOCs. From AUTOMAT-PROCELLS, we expect the following results: - a validation of the High-Throughput approach for the study and discovery of materials for PCFCs/PCECs, including the characterization of hydration and transport properties, stability and structural-chemical features, - the production of exhaustive information (hundreds of different compositions tested) on important phase diagrams for proton-conducting solid oxide cells : BaZr0.8Y/Yb0.2O3-d- BaCe0.8Y/Yb0.2O3-d- BaSn0.8Y/Yb0.2O3-d ; LSM-LSC-LSF, or doped BaCo0.4Fe0.4Zr0.2FeO3-d, - the identification of original compositions with optimized exchange, transport and electrochemical properties for proton-conducting solid oxide cells, - the creation of technical advances in the field of High-throughput Experiments for materials discovery like (i) the design and fabrication of a furnace for large samples particularly adapted to the characterization of materials library (ii) the development of a low-cost route for combinatorial deposition of oxide materials (see below) (iii) the adaptation of SIMS for the characterization of combinatorial films. - to help for the emergence of a dynamic in the French materials science community (starting from the application on fuel cells) toward the use of automated and parallelized approaches in research.

There is growing consensus that mineral crystallization from ionic solutions involves a liquid-liquid phase separation (LLPS), where a reactant-rich liquid separates from water, just as in organic crystallization. However, mineral LLPS remains elusive because of the short lifetime of the liquid phases prior to solid precipitation. TITANS will provide fundamental knowledge on mineral LLPS by addressing the most debated questions in order to: 1) assess how liquid are the reactant-rich structures, 2) determine if they are a metastable thermodynamic phase or a kinetic pattern, and 3) rationalize the intricate evolutions of the liquid, the amorphous solid and the crystal. We will combine advanced fast microfluidic mixers, in situ characterization of structure, chemistry and dynamics at the synchrotron and in the laboratory, and in and out-of-equilibrium modeling. TITANS will thus provide a reliable depiction of the ubiquitous soft matter processes preceding the crystallization of carbonates, oxalates and sulfates.

Determining the conformation of a small molecule inside a huge molecular weight structure is crucial for the understanding of the fundamental molecular processes that drive the interactions. Many of these complexes are neither crystalline nor soluble and are thus difficult to study by classical methods such as NMR, X-ray diffraction etc. To the best of our knowledge, a limited number of atomic structures of such systems were reported to date. In our project, we propose a new strategy based on the synergetic combination of organic synthesis (chimio-, regio- and stereo-specific tritium labeling; carbon-13 and nitrogen-15 labeling), solid state NMR and molecular modeling as a novel unique tool-kit to determine the conformation of a small molecule embedded in a high molecular and non-crystalline assembly. To develop our strategy we choose a model small molecule, the Phe-Phe dipeptide that forms either crystals or self-assembled nanotubes depending on the solvent. If the crystalline atomic structure of Phe-Phe has been solved, the structure of the self-assembled nanotubes of Phe-Phe is still unknown. To solve such structure, precise intra- and intermolecular distances should be determined to get not only the conformation of the molecule but also its packing within the assembly. We will develop our strategy (chemical synthesis, solid state NMR and molecular modeling) on Phe-Phe crystal. This strategy will be then applied to determine the atomic structure of Phe-Phe nanotubes. The result of this project is expected to pave the way for numerous forthcoming applications such as pharmacology, biology (determination of a ligand structure bounded to its receptor, self-assembled molecules) and nanotechnology (determination of the conformation and the precise position of a small molecule within a supramolecular architecture).

The HighEneCh ANR project aims to initiate and organize collaborative work between specialists of electron spectroscopy and instrumentation at large-scale facilities (SOLEIL, UPMC – LCP-MR), radiation chemistry (CEA - NIMBE), microfluidic systems (CEA – NIMBE) and ab initio molecular dynamics simulations (UPMC - IMPMC), with the goal of extending the boundaries of fundamental knowledge of the different mechanisms involved in the chemistry in aqueous environments triggered by high-energy photons. Using complementary approaches, the HighEneCh project consortium wants, over the 48 months’ duration of the project, to achieve a global view of the radiolysis of pure water and of water/biomolecule mixtures irradiated with soft X-ray and hard X-ray synchrotron light, with a special focus on the chemical effects of core ionizations. Irradiation with high-energy photons (x-ray) produces charged and neutral species which can both influence the production of the damage caused by the radiation via direct and indirect processes, respectively. The original approach of our consortium is to combine state-of-the-art quantification methods for the detection of radical species with photo/Auger electron spectroscopy on liquids, supported by ab initio molecular dynamics simulations to elucidate the fundamental mechanisms of the interaction of high energy photons with biological material surrounded by a liquid. Detection of radicals will be based on chemical scavenging methods that will be used to quantify the production of OH and HO2 radicals, under different irradiation conditions. In the first experiments, irradiation studies will be carried out in part with an up-graded version of an existing movable experimental set-up (IRAD set-up), which be upgraded with a microfluidic cell, and used under anaerobic conditions. Photo/Auger electron spectroscopy studies of liquids will utilize a new portable apparatus (MultiSpec Set-up), where a recycling liquid microjet will be used in vacuum. Recovering the irradiated sample is crucial for our project to be able to perform off-line analytical measurements (fluorescence yield, mass spectrometry) on the same sample measured by electron spectroscopy. We also plan to recycle sample in a closed loop system in order to progressively increase the average dose and follow its chemical evolution. Electron coincidence techniques will be used on the liquids to associate the photoelectron and Auger spectra, and thus have a better understanding of the effects of the environment during the decay processes of the initial core hole. Our studies will extend from pure water to solutions of sugar phosphates such as 5 ribose phosphate and 2-deoxyribose 5-monophosphate, a biomimetic molecule of the DNA backbone. A close collaboration with theoreticians will be a valuable component of the consortium. We will investigate the early stages of the dissociation of core ionized water or sugar-phosphate molecules, embedded in liquid water, at the femto to picosecond time scale, using ab initio Molecular Dynamics (MD) simulation. To support the experimental findings for the production of superoxide radicals in pure water, we will first model the dynamics induced by an oxygen-K ionization, starting from configurations in which one water molecule is doubly ionized and another one, localized within one nanometer, is singly ionized. Such an event is highly probable since, after Auger decay, the core-ionized water molecule will carry a double vacancy. Moreover, the photo and Auger electrons are ejected with a few hundred electronvolts kinetic energy and can ionize a neighbouring water molecule with a high probability since their mean free path is only a few nanometers in water. The results will be used as input data for the Kinetic Monte-Carlo simulation to extend to the chemistry occurring on a time scale of microseconds.

Perovskite solar cells (PSCs) have become a trending technology in photovoltaic research due to a rapid increase in efficiency in recent years. In 2020, a record efficiency of 25.5% close from Shockley-Queisser theoretical limit of 30% was reported. Tandem solar cells offer an alternative to go beyond but stability still remains an issue. In our project, we will bring together our complementary expertise in molecular and macromolecular syntheses, thin film morphology tuning and cell device engineering to improve the stability of highly efficient inverted perovskite cells using new electron transport layers (ETL) with high electron mobility and high stability. We will design and synthesize new n-type fullerene free semiconductors. Introduction of cross-linkable groups will lead to stabilized ETLs by thermally-induced cross-linking after film formation. The efficiency and stability of these ETLs will be finally evaluated through their incorporation in tandem configuration.