Comprehensive study to design advanced metal-carbide@garaphene and metal-carbide@iron oxide nanoparticles with tunable structure by the laser ablation in liquid

Core-shell nanoparticles represent a class of materials that exhibit a variety of properties. By rationally tuning the cores and the shells in such nanoparticles (NPs), a range of materials with tailorable properties can be produced which are of interest for a wide variety of applications. Herein, experimental and theoretical approaches have been combined to show the structural transformation of NPs resulting to the formation of either NiFexCy encapsulated in ultra-thin graphene layer (NiFe@UTG) or Ni3C/FexCy@FeOx NPs with the universal one-step pulse laser ablation in liquid (PLAL) method. Analysis suggests that carbon in Ni3C is the source for the carbon shell formation, whereas the final carbon-shell thickness in the NPs originates from the difference between Ni3C and FexCy phases stability at room temperature. The ternary Ni-Fe-C phase diagram calculations reveal the competition between carbon solubility in the studied metals (Ni and Fe) and their tendency toward oxidation as the key properties to produce controlled core-shell NP materials. As an application example, the electrocatalytic hydrogen evolution current on the different NPs is measured. The electrochemical analysis of the NPs reveals that NiFe@UTG has the best performance amongst the NPs in this study in both alkaline and acidic media.Peer reviewe

Intercalation of Lithium Ions from Gaseous Precursors into beta-MnO2 Thin Films Deposited by Atomic Layer Deposition

LiMn2O4 is a promising candidate for a cathode material in lithium-ion batteries because of its ability to intercalate lithium ions reversibly through its three-dimensional manganese oxide network. One of the promising techniques for depositing LiMn2O4 thin-film cathodes is atomic layer deposition (ALD). Because of its unparalleled film thickness control and film conformality, ALD helps to fulfill the industry demands for smaller devices, nanostructured electrodes, and all-solid-state batteries. In this work, the intercalation mechanism of Li+ ions into an ALD-grown beta-MnO2 thin film was studied. Samples were prepared by pulsing (LiOBu)-Bu-t and H2O for different cycle numbers onto about 100 nm thick MnO2 films at 225 degrees C and characterized with X-ray absorption spectroscopy, X-ray diffraction, X-ray reflectivity, time-of-flight elastic recoil detection analysis, and residual stress measurements. It is proposed that forPeer reviewe

The Youngest Victims: Children and Youth Affected by War

In 1989, the United Nation Convention on the Rights of the Child declared, “[state parties] shall take all feasible measures to ensure protection and care of children who are affected by an armed conflict.” In addition to attempting to secure the welfare of children in armed conflict, the Convention went on to ban the recruitment and deployment of children during armed conflict. Despite the vast majority of sovereign nations signing and ratifying this agreement, this treaty, unfortunately, has not prevented children and youth from witnessing, becoming victims of, or participating in political, ethnic, religious, and cultural violence across the past three decades. This chapter offers an “ecological perspective” on the psychosocial consequences of exposure to the trauma of war-related violence and social disruption

Active IrO2 and NiO thin films prepared by atomic layer deposition for oxygen evolution reaction

| openaire: EC/H2020/722614/EU//ELCORELAtomic layer deposition (ALD) is a special type of chemical vapor deposition (CVD) technique that can grow uniformed thin films on a substrate through alternate self-limiting surface reactions. Recently, the application of these thin film materials to catalytic systems has begun to attract much attention, and the capacity to deposit these catalytic films in a highly controlled manner continues to gain importance. In this study, IrO2 and NiO thin films (approximately 25 to 60 nm) were deposited on industrial Ni expanded mesh as an anode for alkaline water electrolysis. Different ALD operating parameters such as the total number of deposition cycles, sublimation and deposition temperatures, and precursors pulse and purge lengths were varied to determine their effects on the structure and the electrochemical performance of the thin film materials. Results from the electrochemical tests (6 M KOH, 80◦C, up to 10 kA/m2) showed the catalytic activity of the samples. Oxygen overpotential values (ηO2) were 20 to 60 mVlower than the bare Ni expanded mesh. In summary, the study has demonstrated the feasibility of using the ALD technique to deposit uniformed and electroactive thin films on industrial metallic substrates as anodes for alkaline water electrolysis.Peer reviewe

Isothermal crystallization of polypropylene/expanded graphite microcomposites: effect of graphite size and volume fraction.

National audienc

High performance silicon electrode enabled by titanicone coating

Funding Information: Funding from the European Comission and Tecnio Spring under the Grant agreement TECSPR18-1-0049 Towards High Energy All Solid State Lithium Batteries (SOLBAT) is gratefully acknowledged. IREC acknowledges support of Generalitat de Catalunya. The authors like to acknowledge the support of Aalto University. Publisher Copyright: © 2022, The Author(s).This paper presents the electrochemical performance and characterization of nano Si electrodes coated with titanicone (TiGL) as an anode for Li ion batteries (LIBs). Atomic layer deposition (ALD) of the metal combined with the molecular layer deposition (MLD) of the organic precursor is used to prepare coated electrodes at different temperatures with improved performance compared to the uncoated Si electrode. Coated electrodes prepared at 150 °C deliver the highest capacity and best current response of 1800 mAh g−1 at 0.1 C and 150 mAh g−1 at 20 C. This represented a substantial improvement compared to the Si baseline which delivers a capacity of 1100 mAh g−1 at 0.1 C but fails to deliver capacity at 20 C. Moreover, the optimized coated electrode shows an outstanding capacity of 1200 mAh g−1 at 1 C for 350 cycles with a capacity retention of 93%. The improved discharge capacity, electrode efficiencies, rate capability and electrochemical stability for the Si-based electrode presented in this manuscript are directly correlated to the optimized TiGL coating layer deposited by the ALD/MLD processes, which enhances lithium kinetics and electronic conductivity as demonstrated by equivalent circuit analysis of low frequency impedance data and conductivity measurements. The coating strategy also stabilizes SEI film formation with better Coulombic efficiencies (CE) and improves long cycling stability by reducing capacity lost.Peer reviewe

Dispersion and crystallization of polypropylene/expanded graphite microcomposites: effect of graphite size

International audiencePolymer crystallization can be considered at different levels: nucleation, growth and overall kinetics. Because these levels are, in turn, materials dependent, the present work intends to evaluate how size and volume fraction of expanded graphite particles can affect the three crystallization levels in an isotactic polypropylene in quiescent and isothermal conditions.Neat polypropylene (PP) was Moplen HP400R (LyondellBasell). The selected expanded graphite particles were KNG-180, KNG-150 [1] and KNG-G5 [2] (Knano®). Composites with three volume fractions of graphite varying from 0.3 to 2 % were prepared in the same conditions in an internal mixer. The dispersion state of the particles in the composites was characterized at different scales using SEM and TEM. Crystallization was studied by optical microscopy, DSC and X-ray diffraction.Expanded graphite particles were found to have a flake shape with a micrometric size. At a given volume fraction, graphite particles enhanced the kinetics of crystallization of PP especially in the presence of KNG-150, KNG-G5 and KNG-180, acting as nucleating agents [3]. The crystal nucleation of PP was found to be located on the surface of the micrometric graphite particles giving rise to transcrystalline growths in the microcomposites [4]; but related to the difference in stacking dimension of graphite particles. Radial growths were also observed. Crystalline planes of PP (040) and of graphite (002) were found to be oriented parallely.References:[1] G. Chen, C. Wu, W. Weng, D. Wu, W. Yan, Polymer 44 (2003) 1781[2] W. Zhao, F. Wu, H. Wu, G. Chen, Journal of Nanomaterials (2010) 528235[3] S. Zhao, F. Chen , Y. Huang, J-Y. Dong, C.C. Han, Polymer 55 (2014) 4125[4] M.C. Branciforti, C.A. Oliveira, J.A. De Sousa, Polymer Advanced Technologies 21 (2010) 322Acknowledgement: Expanded graphite particles were kindly provided by the CNRS research group project n°3661 ‘GDR PolyNano’

Crystallization behavior of polypropylene/graphene nanoplatelets composites

International audienceInterest in graphite fillers has grown since the separation of graphene from graphite by micromechanical cleavage. The object of the paper is to understand the influence of graphene nanoplatelets (GNPs) with different sizes on the crystallization behavior of a polyolefin matrix such as polypropylene (PP), after elaboration by melt mixing and compression molding. Composites with volume fractions of graphene nanoplatelets ranging from 0.3 to 2 vol% were prepared. The particle dispersion states in the composites were characterized at different scales using Scanning and Transmission Electron Microscopies (SEM and TEM). Polypropylene crystallization and orientation were investigated using optical microscopy, Differential Scanning Calorimetry (DSC) and X-ray diffraction. This paper discusses the strong acceleration of crystallization kinetics due to the presence of GNPs. The micrometric flake-shaped GNPs act as nucleating agent and induce an epitaxial growth of alpha (α) crystalline phase of PP. The nucleating effect is related to the surface of the particles available for heterogeneous nucleation. Radial spherulitic growths are observed from the smallest micrometric particles. The coarsest GNPs, easily oriented by flow, favor PP transcrystallinity, in such a way that (010) plane of PP is parallel to (001) plane of graphene nanoplatelets

High Performance Hydrogen Evolution Reaction Catalyst Based on Single-Walled Carbon Nanotubes Decorated by RuOx Nanoparticles

| openaire: EC/H2020/722614/EU//ELCORELWe report a cathode material based on plasma-treated single-walled carbon nanotubes decorated by RuOx nanoparticles using atomic layer deposition. We have examined cathode performance towards hydrogen evolution reaction by tailoring material wettability, conductivity yielded by plasma treatment, and the catalyst loading. We discuss that nucleation of particles is facilitated by the appearance of carboxylic and hydroxyl groups triggered by oxygen plasma action. The best performance is associated with samples containing RuOx particles of 4–5 nm, which show hydrogen evolution onset potential to be about −5 mV (vs. RHE) in 0.5 M H2SO4 measured at a current density of −1 mA cm−2 and Tafel slope of 47.5 mV/dec. The material possesses stable performance at −10 mA cm−2 with a potential of about −160 mV.Peer reviewe