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Insights into corrosion behaviour and discharge performance improvement in Mg-Air batteries using sodium acetate
No full textInternational audienceThe discharge behaviour of Mg-air batteries with pure Mg anodes is presented, highlighting the improved anodic utilization efficiency and specific capacity in sodium acetate (NaOAc) electrolyte over sodium chloride (NaCl) electrolyte. Moreover, only a modest reduction in discharge potential was noted at increased current densities in half-cell tests. NaOAc electrolyte, containting less aggressive acetate ions, enables the formation of a homogeneous and protective oxide layer, in contrast to the chloride ions in NaCl electrolyte, which promote oxide breakdown and localized corrosion. The protective layer formed in NaOAc electrolyte limits Mg degradation, reduces H2 evolution rate, and enhances discharge performance. The surface characterizations by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM) reveal a denser corrosion layer formed on the surface of pure Mg anode in the NaOAc electrolyte, contributing to improved corrosion resistance and increased anodic utilization efficiency. Full-cell discharge tests using pure Mg, Mg-0.2Ca, and AZ31 alloy show that the anodic utilization efficiency and specific energy are improved in NaOAc electrolyte, particularly for Mg-0.2Ca, with energy density of 2066 Wh/kg at 2 mA/cm2. These findings suggest that NaOAc is a promising electrolyte for improving the performance of Mg-air batteries for different Mg-based anode materials
Ion desolvation for boosting the charge storage performance in Ti3C2 MXene electrode
No full textInternational audienceClarifying the relationship between ion desolvation, ion-electrode interactions, and charge storage capacity during ion intercalation in host electrode materials is crucial for advancing fast and efficient energy storage systems. However, the absence of direct evidence for ion desolvation and lack of detailed understanding of the interactions between surface terminations and intercalated cations (Li ions)/solvents hinder the exploration of their effects on energy storage mechanisms. In this paper, we study the intercalation of Li ions from a non-aqueous electrolyte in two-dimensional metal carbides Ti 3 C 2 MXenes with different surface chemistries: HF-Ti 3 C 2 (F-, OH- and O-terminated) and MS-Ti 3 C 2 (O- and Cl-terminated) MXenes. We are able to visualize the full ion desolvation and solvents-ions co-intercalation in the interlayers of MS-MXene and HF-MXene, respectively at the atomic scale. The combination of several techniques and characterization tools reveal that the complete ion desolvation in Cl- and O-terminated MS-Ti 3 C 2 MXenes is associated with the formation of a dense solid electrolyte interface layer, resulting in improved charge storage capacity. The O-rich surface terminations of MS-MXenes are found to be responsible for the efficient Li ions storage. These findings shed lights on identifying the critical role of non-electrostatic ion-electrode interactions and ion desolvation in designing high-performance energy storage devices
Quasi-2D Ruddlesden-Popper phase induced preferentially oriented FA1-xMAxPbI3 for high-performance sequential perovskite solar cells
No full textInternational audienceIncorporating large alkylammonium cations or crystal seeds into 3D perovskite has been found effective in manipulating crystallographic orientation and increasing the intrinsic stability of polycrystalline perovskite thin films. However, an excess of large-size cations within the bulk layer can detrimentally impact charge transport, resulting in relatively suboptimal device performance. In this study, we substituted a portion of methylammonium chloride (MACl) with an appropriate amount of long-chain n-butylammonium chloride (BACl) in order to modulate the crystallization kinetics of two-step FAPbI3 polycrystalline films. We show that the addition of BA + cation facilitates the in-situ formation of Ruddlesden-Popper (RP) quasi-2D phases (BA2MAn-1PbnI3n+1, n≥2) at the initial crystallization stage, which, in turn, enables the growth of the preferentially (100) oriented 3D α-FAPbI3 perovskite films. Furthermore, the mixed alkylammonium system attenuates the elimination rate of dissociation of hydrochloride and alkylamine from deprotonated alkylammonium Cl-salts, yielding films with homogeneous morphology and negligible trapmediated recombination. Remarkably, only traces (measured at 2 % cation proportion) of BA molecules were detected on the layer surface after complete induction of the oriented growth. The optimal device employing the mixed alkylamine hydrochloride achieved a power conversion efficiency of 23.23% and exhibited exceptional stability, retaining 90% of its initial performance over 2000 hours of storage in a nitrogen-filled glovebox
Influence of P(V3D3-co-TFE) Copolymer Coverage on Hydrogen Detection Performance of a TiO2 Sensor at Different Relative Humidity for Industrial and Biomedical Applications
No full textInternational audienceThe detection of hydrogen gas is crucial for both industrial fields, as a green energy carrier, and biomedical applications, where it is a biomarker for diagnosis. TiO2 nanomaterials are stable and sensitive to hydrogen gas, but their gas response can be negatively affected by external factors such as humidity. Therefore, a strategy is required to mitigate these influences. The utilization of organic–inorganic hybrid gas sensors, specifically metal oxide gas sensors coated with ultra-thin copolymer films, is a relatively novel approach in this field. In this study, we examined the performance and long-term stability of novel TiO2-based sensors that were coated with poly(trivinyltrimethylcyclotrisiloxane-co-tetrafluoroethylene) (P(V3D3-co-TFE)) co-polymers. The P(V3D3-co-TFE)/TiO2 hybrid sensors exhibit high reliability even for more than 427 days. They exhibit excellent hydrogen selectivity, particularly in environments with high humidity. An optimum operating temperature of 300 °C to 350 °C was determined. The highest recorded response to H2 was approximately 153% during the initial set of measurements at a relative humidity of 10%. The developed organic–inorganic hybrid structures open wide opportunities for gas sensor tuning and customization, paving the way for innovative applications in industry and biomedical fields, such as exhaled breath analysis, etc
Elastic, strong and tough ionically conductive elastomers
No full textInternational audienceStretchable elastic materials with high strength, toughness, and good ionic conductivity are highly desirable for wearable devices and stretchable batteries. Unfortunately, limited success has been reported to attain all of these properties simultaneously. Here, we report a family of ionically conductive elastomers (ICEs) without compromise between mechanical properties (high stiffness, reversible elasticity, fracture resistance) and ionic conductivity, by introducing a multiple network elastomer (MNE) architecture into a low polymer. The ICEs with the MNE architecture exhibit a room temperature ionic conductivity of the order of and stress at break of ~8 MPa, whereas the simple networks without an MNE architecture show two orders magnitude lower ionic conductivity () and comparably low strength (<1.5 MPa) at 25 °C than their MNE architecture based counterparts. The MNE architecture with a low monomer combines the stiffness and fracture toughness given by sacrificial bond breakage while improving ionic conductivity through increased segmental mobility
Elucidating Carrier Dynamics and Interface Engineering in Sb<sub>2</sub>S<sub>3</sub> : Toward Efficient Photoanode for Water Oxidation
No full textInternational audienceConjugation of low‐cost and high‐performance semiconductors is essential in solar‐driven photoelectrochemical (PEC) energy conversion. Sb2S3 is a wide‐bandgap (≈1.7 eV) semiconductor with the potential to deliver a maximum photocurrent density of 24.5 mA cm −2 , making it highly attractive for PEC water splitting applications. However, bulk Sb2S3 exhibits intrinsic recombination issues and low electron–hole separation, posing a limit to photocurrent generation. This study clarifies the carrier dynamics by ultrafast spectroscopy measurements and proposes the design of a heterojunction between Sb2S3 and SnO2, with suitable band‐edge energy offset. The SnO2/Sb2S3 heterojunction enhances the charge separation efficiency, resulting in improvement of the photocurrent. The SnO2/Sb2S3 photoanode, fabricated entirely by vapor deposition processes, demonstrates photoelectrochemical water oxidation with a photocurrent density up to ≈3 mA cm −2 at 1.38 V versus RHE
Engineered mesoporous silica nanosystems with organotin( iv ) complexes containing 1-(quinolin-8-yliminomethyl)naphthalen-2-ol ligand for cancer cell targeting
No full textInternational audienceThe development of targeted nanotherapeutics has emerged as a promising approach to improve the efficacy and safety of anticancer treatments. This manuscript presents the synthesis, detailed characterization, and biological evaluation of novel mesoporous silica nanoparticles (sMSNs) functionalized with organotin(IV) complexes containing 1-(quinolin-8-yliminomethyl)naphthalen-2-ol ligand, which have also been selectively targeted using biotin (BT) and folic acid (FA). The systems have been comprehensively characterized using microscopy, nitrogen adsorption–desorption isotherms, and several spectroscopic methods confirming the successful conjugation of organotin(IV) complexes and targeting ligands, as well as the preservation of the structural integrity of the nanoparticles. The cytotoxic potential of the functionalized sMSNs was assessed in vitro using cancer cell lines (HeLa and MCF-7) and non-cancerous cell lines (Hek 293T and RPE-1) to evaluate their selectivity and biocompatibility. The results demonstrated that the tin-functionalized nanoparticles exhibited a significant antiproliferative activity. Notably, the incorporation of BIO and FA as targeting ligands enhanced selectivity toward cancer cells, minimizing toxicity in healthy cells. Our compounds were found to have a higher cytotoxic activity than cisplatin. These findings highlight the potential of tin-functionalized mesoporous silica nanoparticles as a robust platform for targeted cancer therapy, offering enhanced efficacy and reduced off-target effects compared to conventional platinum-based treatments
Enhanced corrosion resistance of 2024 aluminum alloys with Cr2O3 thin layers by Atomic Layer Deposition
No full textInternational audienceThis research explores the use of chromium oxide (Cr 2 O 3 ) thin layers grown by Atomic Layer Deposition (ALD) as protective coating to enhance the corrosion resistance of 2024 aluminum alloys. In order to obtain sufficiently dense and uniform Cr 2 O 3 layers, the ALD process was tailored in terms of alloy surface pretreatment before the main Cr 2 O 3 ALD process. The corrosion resistance of both Cr 2 O 3 coated and non-coated aluminum alloys was evaluated in a corrosive 0.1 M KOH environment using in situ optical microscopy and ex situ surface analysis techniques, including X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and a neutral environment containing chlorides. Findings revealed that the Cr 2 O 3 -coated samples exhibited significantly reduced reactivity, highlighting the excellent corrosion protection provided by the Cr 2 O 3 thin films. Although surface analysis revealed the presence of submicron defects within the Cr 2 O 3 layer, which could act as corrosion initiation sites, the occurrence of these defects was mitigated with increasing Cr 2 O 3 layer thickness. Additionally, after the corrosion test, an enrichment of copper and aluminum oxides at the layer surface was observed, suggesting preferential attack at intermetallic phases in corrosive environment.</div
Indanone Building Blocks from Lignin Related C-9 Plaform Molecules
No full textLignin-based aryl 3-hydroxypropanones were converted into indanones via domino dehydration/Nazarov cyclization in the presence of a superacid. The cyclization was studied in detail, and the resulting indanones were engaged in two postfunctionalizations: a reduction/elimination domino sequence and a ring expansion. Lastly, the method has been successfully applied to the synthesis of the anti-Alzheimer drug donepezil.</div
Unveiling complex lithiation/delithiation mechanism in AgNbO3 model perovskite using operando X-ray absorption spectroscopy
No full textInternational audienceIn AgNbO3 perovskite structure, electrochemical activation is speculated during the first lithiation cycle enabling the material to reversibly store Li+ by the contributions of both Ag and Nb cation. However, the origin of electrochemically induced structural activation and understanding of cations involvement in complex Li+ storage mechanism is still elusive. Herein, operando synchrotron X-ray absorption spectroscopy (XAS) was applied to clarify this mechanism under different cycling conditions. Ag K-edge XAS measurements during first lithiation revealed a gradual Ag+ to Ag0 reduction starting at a relatively high potential of 1.0 V vs Li+/Li, thus creating vacancies in the lattice for Li+ insertion and inducing a crystalline-to-amorphous structural transition. Below 0.3 V vs Li+/Li, metallic Ag forms multiple intermetallic Li-Ag alloys, resulting in lithium-rich Li9Ag at the end of lithiation. Simultaneously, Nb K-edge XAS measurements indicate an irreversible Nb5+ to Nb3+ reduction with formation of metastable phases during first lithiation. Upon extended cycling at high current densities, intermediate phases sustain reversible Li+ storage through Nb-redox activity and Li-Ag (de)alloying reactions, facilitating fast charging capability. This study will help in designing new conversion-alloying type negative electrodes for fast-charging batteries