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Dynamic correlations in a polar fluid: confronting stochastic density functional theory to simulations
No full textInternational audienceUnderstanding the dynamic behavior of polar fluids is essential for modeling complex systems such as electrolytes and biological media. In this work, we develop and apply a Stochastic Density Functional Theory (SDFT) framework to describe the polarization dynamics in the Stockmayer fluid, a prototypical model of dipolar liquids consisting of Lennard-Jones particles with embedded point dipoles. Starting from the overdamped Langevin dynamics of dipolar particles, we derive analytical expressions for the intermediate scattering functions and dynamic structure factors of the longitudinal and transverse components of the polarization field, within linearized SDFT. To assess the theory's validity, we compare its predictions with results from Brownian Dynamics simulations of the Stockmayer fluid. We find that SDFT captures the longitudinal polarization fluctuations accurately, while transverse fluctuations are underestimated due to the neglect of dipolar correlations. By incorporating the Kirkwood factor into a modified SDFT, we recover quantitative agreement for both components across a range of dipole strengths. This study highlights the utility of SDFT as a coarse-grained description of polar fluid dynamics and provides insights into the role of collective effects in polarization relaxation
Chlorométhylation directe de liaisons C(sp<sup>3</sup>)-H par activation du CH₂Cl₂ à l'aide d'un plasma non thermique
No full textInternational audienceNon-thermal plasma has been implemented for chemical activation of CH₂Cl₂ in a continuous flow gas-liquid system operating at ambient temperature and pressure. In this study, we present a direct and catalyst-free approach for the chloromethylation of saturated hydrocarbons. The reaction test resulted in the functionalization of cyclohexane without a catalyst or additives, achieving a total yield of 30% of chlorinated products with a residence time of 60 s. The influence of substrate concentration, gas/liquid flow ratio, energy density and residence time was studied, which resulted in a proposal of reaction pathway where the reaction is initiated by the C-Cl dissociation in CH₂Cl₂ , followed by H-abstraction on C(sp3)-H and radical recombination. These mechanistic insights provide valuable knowledge for the advancement of plasma chemistry. Furthermore, the use of deuterated dichloromethane allows the introduction of deuterium into saturated hydrocarbons.Le plasma non thermique a été utilisé pour l’activation chimique du CH₂Cl₂ dans un système gaz-liquide en flux continu fonctionnant à température et pression ambiantes. Dans cette étude, nous présentons une approche directe et sans catalyseur pour la chlorométhylation des hydrocarbures saturés. Le test de réaction a permis la fonctionnalisation du cyclohexane sans catalyseur ni additifs, atteignant un rendement total de 30 % de produits chlorés avec un temps de séjour de 60 secondes. L’influence de la concentration du substrat, du ratio de flux gaz/liquide, de la densité énergétique et du temps de séjour a été étudiée, ce qui a conduit à une proposition de mécanisme réactionnel où la réaction est initiée par la dissociation C-Cl dans le CH₂Cl₂, suivie d’une abstraction d’hydrogène sur C(sp3)-H-H et d’une recombinaison radicalaire. Ces éléments mécanistiques apportent des connaissances précieuses pour le développement de la chimie plasma. De plus, l’utilisation du dichlorométhane deutéré permet l’introduction de deutérium dans les hydrocarbures saturés
Revitamize LFP! Ascorbic Acid‐Assisted Direct Regeneration of Spent LiFePO4 for Li‐ion Batteries
No full textInternational audienceThe increasing demand for lithium‐ion batteries (LIBs), primarily driven by the expanding electric vehicle market and the growing need for efficient energy storage, presents both significant opportunities and challenges. The efficient and cost‐effective regeneration of spent LIBs is crucial to minimizing environmental impact and fostering a true circular economy for battery materials. In this study, we introduce an innovative one‐step lithiation process for spent LiFePO4 cathodes, conducted in aqueous solution under ambient conditions. This method utilizes readily available and low‐cost reagents, including a lithium source and ascorbic acid (vitamin C) as a green reducing agent, offering a substantial advantage over traditional techniques that require harsh conditions and complex setups. The lithiation reaction proceeds rapidly, producing pure and fully regenerated LFP. This environmentally friendly process has been successfully demonstrated at the scale of 18650 cells with electrodes composed entirely of recycled LFP. These cells exhibit excellent electrochemical performance, even after 1000 cycles at 1C rate, comparable to those made with pristine LFP. By providing a sustainable, cost‐effective, and easily scalable solution for LFP cathode regeneration, our approach supports the closure of the materials loop, contributing to the sustainable management of LIBs and advancing the shift toward a circular economy
Heptafluorobutyronitrile (C<sub>4</sub>F<sub>7</sub>N), Hydrolysis, a Density Functional Theory (DFT) Investigation
No full textInternational audienceHeptafluorobutyronitrile (C4F7N) has received much consideration as an effective substitute to sulfur hexafluoride (SF6) in the electrical industrial sector over the last decade. However, liability is the key to emerging technology, and the thermoelectric aging of the insulation gases may produce unavoidable consequences that raise concerns for the operator and human safety. Recently, numerous pieces of literature mentioned the production of crystals in the form of amide and dimer (ligand) generated from the aging of C4F7N with few water molecules. It was found that the hydrolysis of fluoronitrile chemical reactions initial with the production of amide (C4H2F7NO) and following, with the addition of C4F7N molecules, accelerates the reaction to produce dimer (C8H2F14N2O) and further is the possibility to generate various range of byproducts. Thermodynamically, C4F7NH2O + C4F7N → C8H2F14N2O is the favourable chemical reaction with a 23 kcal/mol energy barrier that generates a dimer molecule. Furthermore, in presence of paramagnetic ion (typically Cu (II)), a Cooper based complex (as purple crystals) may appear. Gibbs free energy at elevated temperature indicates the driving force is needed to accelerate the reaction except C8H2F14N2O + H2O → C12H2F21N3O, whose energy values throughout remain consistent. Theoretical calculations reveal the water acts as a strong catalytic that can abruptly reduce the energy barrier of the initial reaction from 59 to 10 kcal mol-1 and open the pathway to generate other byproducts
Hexaphyrin-Cyclodextrin Hybrids: Switching between Möbius and Hückel Aromatic Systems in Chiral Environment
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New inorganic-polymer composite materials for the positive electrode of asymmetric supercapacitors
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Synthesis and Study of the Application of Iron, Nitrogen-Doped High-Surface-Area Carbon for Li–S Batteries
No full textInternational audienceDespite their promising theoretical performance, lithium-sulfur (Li-S) batteries are often limited by low efficiency, primarily due to the solubility of lithium polysulfides and the low conductivity of sulfur electrodes. Enhancing the incorporation of sulfur into porous carbon with improved polarity could significantly boost Li-S battery performance. In this study, we doped carbon xerogels with nitrogen atoms and decorated them with iron-based nanostructures using a straightforward and scalable method. The decomposition of nitrogen-containing additives at varying temperatures—specifically 750°C (FeNC-750) and 950°C (FeNC-950) resulted in alterations to the porosity of the xerogel compared to the pristine structure. After impregnating these structures with sulfur to develop the sulfur electrode, we assessed the electrochemical performance of FeNC-750@S and FeNC-950@S, varying the sulfur content and the electrolyte-to-sulfur (E/S) ratio. Our results indicated that the electrochemical performance of the sulfur electrode with high sulfur content was significantly influenced by both the E/S ratio and the porosity of the host materials. Notably, the sulfur electrode with over 80% sulfur content, designated FeNC-950@S80, achieved a discharge capacity of 600 mAh g⁻¹ with an E/S ratio of 7.5 mL g⁻¹ and an electrode loading of 3.5 g cm⁻², demonstrating excellent capacity retention of 96% over 100 cycles at a rate of 0.1 C
Artificial Intelligence Paradigms for Next-Generation Metal–Organic Framework Research
No full textInternational audienceAfter the development of the famous “Transformer” network architecture and the meteoric rise of artificial intelligence (AI)-powered chatbots, large language models (LLMs) have become an indispensable part of our daily activities. In this rapidly evolving era, “all we need is attention” as Google’s famous transformer paper’s title [Vaswani et al., Adv. Neural Inf. Process. Syst. 2017, 30] implies: We need to focus on and give “attention” to what we have at hand, then consider what we can do further. What can LLMs offer for immediate short-term adaptation? Currently, the most common applications in metal–organic framework (MOF) research include automating literature reviews and data extraction to accelerate the material discovery process. In this perspective, we discuss the latest developments in machine-learning and deep-learning research on MOF materials and reflect on how their utilization has evolved within the LLM domain from this standpoint. We finally explore future benefits to accelerate and automate materials development research
Relationship between molecular structures and thermogravimetric properties of gallium–amidinate based compounds
No full textInternational audienceThe ability to predict the thermal properties of molecular compounds is essential for their successful integration into vapor-phase processes such as atomic layer deposition (ALD) and chemical vapor deposition (CVD), as well as in catalysis and materials synthesis. In this work, we present a systematic study of 24 gallium amidinate complexes, designed to explore the relationship between molecular structure and thermal behavior. The series encompasses a range of structural variations: different ligand substituents, molecular symmetry, and co-ligands. Structural characterization, including in some cases single-crystal X-ray diffraction, was combined with detailed thermal analysis using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) under both atmospheric and reduced pressure conditions. The results reveal clear correlations between thermal properties and ligand architecture, with features such as alkyl chain type, methyl group presence, and overall symmetry playing key roles in determining volatility and stability. Importantly, both symmetric and dissymmetric complexes were found to possess the desired thermal characteristics for vapor-phase deposition processes. Beyond offering valuable design principles for gallium precursors, the dataset generated herein provides a foundation for improving predictive models—empirical and AI-driven alike—towards the rational development of next-generation functional molecular compounds
Bioinorganic chemistry: where from and where to?
No full textInternational audienceBioinorganic chemistry is a multidisciplinary field that bridges the apparent divide between inorganic chemistry and biology. The very name "bioinorganic" is an intriguing oxymoron, as "inorganic" chemistry traditionally refers to the study of the inanimate world, while the "bio" prefix refers to living systems. Bioinorganic chemistry focuses on metallic systems within biological environments, with the dual aims of better understanding these natural systems and leveraging the solutions developed through evolution to design new industrial or therapeutic applications. As a close cousin of the field of metallomics, bioinorganic chemistry shares the fundamental principles that underpin metallomics' systemic analyses of metal-containing biomolecules. In this article, we trace the historical development of bioinorganic chemistry, highlighting its recent advancements and outlining future research challenges in this dynamic interdisciplinary area