Articles de revues : « Nano-structured Transition Metal Oxides »

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Azor-Lafarga, Alberto, Isabel Gómez-Recio, M. Luisa Ruiz-González et José M. González-Calbet. « Atomic Resolution Electron Microscopy : A Key Tool for Understanding the Activity of Nano-Oxides for Biomedical Applications ». Nanomaterials 11, n^o 8 (16 août 2021) : 2073. http://dx.doi.org/10.3390/nano11082073.

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Transition metal oxides constitute one of the most fruitful sources of materials with continuously increasing potential applications prompted by the expectations derived from the reduction of the particle size. The recent advances in transmission electron microscopy, because of the development of lenses, have made it possible to reach atomic resolution, which can provide answers regarding the performance of the transition metal nano-oxides. This critical information is related not only to the ability to study their microstructural characteristics but also their local composition and the oxidation state of the transition metal. Exploring these features is a well-known task in nano-oxides for energy and electronic technologies, but they are not so commonly used for elucidating the activity of these oxides for biomedical applications. Nevertheless, the identification at the atomic level of a certain dopant or the unambiguous determination of the oxidation state of a transition metal in a nano-oxide can be important questions to be answered in a certain biomedical application. In this work, we provide several examples in transition metal nano-oxides to show how atomic-resolution electron microscopy can be a key tool for its understanding.

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Thompson, Kelsey. « Synthesis of Nano-Structured Transition Metal Oxides and Sulfides for Overall Water Splitting and Supercapacitors ». ECS Meeting Abstracts MA2021-01, n^o 51 (30 mai 2021) : 1995. http://dx.doi.org/10.1149/ma2021-01511995mtgabs.

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Alam, Mir Waqas, Muhammad Aamir, Mohd Farhan, Maryam Albuhulayqah, Mohamad M. Ahmad, C. R. Ravikumar, V. G. Dileep Kumar et H. C. Ananda Murthy. « Green Synthesis of Ni-Cu-Zn Based Nanosized Metal Oxides for Photocatalytic and Sensor Applications ». Crystals 11, n^o 12 (26 novembre 2021) : 1467. http://dx.doi.org/10.3390/cryst11121467.

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The preparation, characterization, and application of Nickel oxide (NiO)–Copper oxide (CuO)–Zinc oxide (ZnO) transition nanometal oxides have significantly enhanced their tunable properties for superior multifunctional performances compared with well-known metal oxides. NiO–CuO–ZnO nano transition metal oxides were synthesized by a simple eco-friendly solution combustion method. X-ray diffraction studies revealed distinct phases such as monoclinic, cubic, and hexagonal wurtzite for CuO, NiO, and ZnO, respectively, with NiO having the highest composition. The particle sizes were found to be in the range between 25 and 60 nm, as determined by powder X-ray diffraction. The energy bandgap values were found to be 1.63, 3.4, and 4.2 eV for CuO, ZnO, and NiO, respectively. All metal oxides exhibited a moderate degradation efficiency for AR88 dye. The results of ultraviolet–visible absorption spectra helped identify the bandgap of metal oxides and a suitable wavelength for photocatalytic irradiation. Finally, we concluded that the electrochemical studies revealed that the synthesized materials are well suitable for sensor applications.

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Binks, John H., et John A. Duffy. « Chemical bonding in rock salt structured transition metal oxides ». Journal of Solid State Chemistry 87, n^o 1 (juillet 1990) : 195–201. http://dx.doi.org/10.1016/0022-4596(90)90082-9.

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Wang, Xiaoli, Gongde Wu, Tongfa Jin, Jie Xu et Shihao Song. « Selective Oxidation of Glycerol Using 3% H2O2 Catalyzed by Supported Nano-Au Catalysts ». Catalysts 8, n^o 11 (29 octobre 2018) : 505. http://dx.doi.org/10.3390/catal8110505.

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A series of transition metal oxides or mixed oxides supported nano-Au catalysts were prepared for the selective oxidation of glycerol to glyceric acid using 3% H2O2. It was found that the composition and structure of supports significantly influenced the catalytic performance of catalysts. The mesoporous trimetal mixed oxide (CuNiAlO) supported nano-Au catalysts were more active in comparison with the others. In the present catalytic system, the highest glycerol conversion was 90.5%, while the selectivity of glyceric acid could reach 72%. Moreover, the catalytic performance remained after 11 times of reaction.

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Li, Junhao, Ningyi Jiang, Jinyun Liao, Yufa Feng, Quanbing Liu et Hao Li. « Nonstoichiometric Cu0.6Ni0.4Co2O4 Nanowires as an Anode Material for High Performance Lithium Storage ». Nanomaterials 10, n^o 2 (22 janvier 2020) : 191. http://dx.doi.org/10.3390/nano10020191.

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Transition metal oxide is one of the most promising anode materials for lithium-ion batteries. Generally, the electrochemical property of transition metal oxides can be improved by optimizing their element components and controlling their nano-architecture. Herein, we designed nonstoichiometric Cu0.6Ni0.4Co2O4 nanowires for high performance lithium-ion storage. It is found that the specific capacity of Cu0.6Ni0.4Co2O4 nanowires remain 880 mAh g−1 after 50 cycles, exhibiting much better electrochemical performance than CuCo2O4 and NiCo2O4. After experiencing a large current charge and discharge state, the discharge capacity of Cu0.6Ni0.4Co2O4 nanowires recovers to 780 mAh g−1 at 50 mA g−1, which is ca. 88% of the initial capacity. The high electrochemical performance of Cu0.6Ni0.4Co2O4 nanowires is related to their better electronic conductivity and synergistic effect of metals. This work may provide a new strategy for the design of multicomponent transition metal oxides as anode materials for lithium-ion batteries.

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Oh, Yoo Jin, Michael Hubauer-Brenner et Peter Hinterdorfer. « Influence of Surface Morphology on the Antimicrobial Effect of Transition Metal Oxides in Polymer Surface ». Journal of Nanoscience and Nanotechnology 15, n^o 10 (1 octobre 2015) : 7853–59. http://dx.doi.org/10.1166/jnn.2015.11215.

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In this study, the physical properties of transition metal oxide surfaces were examined using scanning probe microscopic (SPM) techniques for elucidating the antimicrobial activity of molybdenum trioxide (MoO3), tungsten trioxide (WO3), and zinc oxide (ZnO) embedded into the polymers thermoplastic polyurethane (TPU) and polypropylene (PP). We utilized atomic force microscopy (AFM) in the contact imaging mode and its derivative single-pass Kelvin probe force microscopy for investigating samples that were presumably identical in their compositions, but showed different antimicrobial activity in bacterial adhesion tests. Our results revealed that surfaces with larger roughness and higher surface potential variation showed stronger antimicrobial activities compared to smoother and homogeneously charge-distributed surfaces. In addition, capacitance gradient (dC/dZ) measurements were performed to elucidate the antimicrobial activity arising from the different dielectric behavior of the transition metal oxides in this heterogeneous polymer surface. We found that the nano-scale exposure of transition metal oxides on polymer surfaces provided strong antimicrobial effects. Applications arising from our studies will be useful for public and healthcare environments.

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Chen, Huixin, Qiaobao Zhang, Xiang Han, Junjie Cai, Meilin Liu, Yong Yang et Kaili Zhang. « 3D hierarchically porous zinc–nickel–cobalt oxide nanosheets grown on Ni foam as binder-free electrodes for electrochemical energy storage ». Journal of Materials Chemistry A 3, n^o 47 (2015) : 24022–32. http://dx.doi.org/10.1039/c5ta07258a.

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3D hierarchically porous transition metal oxides, particularly those involving different metal ions of mixed valence states and constructed from interconnected nano-building blocks directly grown on conductive current collectors, are promising electrode candidates for energy storage devices such as Li-ion batteries and supercapacitors.

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Acharya, Jiwan, Bishweshwar Pant, Gunendra Prasad Ojha et Mira Park. « Unlocking the potential of a novel hierarchical hybrid (Ni–Co)Se₂@NiMoO₄@rGO–NF core–shell electrode for high-performance hybrid supercapacitors ». Journal of Materials Chemistry A 10, n^o 14 (2022) : 7999–8014. http://dx.doi.org/10.1039/d1ta11063b.

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Nano-hybridization of a core–shell structure integrating a transition metal selenide with oxides results high-capacity electrode materials for energy storage devices thanks to the ample electroactive sites and relatively high electronic conductivity.

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Ramamurthy, Pasupathy, Kandan Chellamani, Bhaarathi Dhurai, Senthil ThankaRajan, Balasubramanian Subramanian et Elango Santhini. « Antimicrobial Characteristics of Pulsed Laser Deposited Metal Oxides on Polypropylene Hydroentangled Nonwovens for Medical Textiles ». Fibres and Textiles in Eastern Europe 25 (30 avril 2017) : 112–19. http://dx.doi.org/10.5604/12303666.1228192.

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In this study, an attempt was made to investigate the antimicrobial activity on polypropylene (PP) hydroentangled nonwoven fabrics coated with transition metal oxides. After etching the nonwoven fabrics with RF plasma, nano-scale coatings of ZnO and CuO were done using the KrF excimer based pulsed laser deposition technique (PLD). Morphological and antimicrobial studies were carried out to elucidate the mechanism of antibiocidal behaviour of the coated fabrics. Results showed significant antibacterial activity of ZnO and CuO coated PP hydroentangled nonwovens with a better activity against gram positive S.aureus than gram negative E.coli. Inherently non-toxic, PP has excellent chemical resistance and the use of specialised PP fibres for hydroentangled nonwovens could offer scope in addition to metal oxide coatings; nano-scale biological materials such as enzymes and drugs could add specific functionality for their use as medical textiles.

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Corà, F., et C. R. A. Catlow. « QM investigations on perovskite-structured transition metal oxides : bulk, surfaces and interfaces ». Faraday Discussions 114 (1999) : 421–42. http://dx.doi.org/10.1039/a904517a.

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Maduraiveeran, Govindhan. « Nanoporous structured mixed transition metal oxides nanomaterials for electrochemical energy conversion technologies ». Materials Letters 283 (janvier 2021) : 128763. http://dx.doi.org/10.1016/j.matlet.2020.128763.

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Umek, Polona, Andrej Zorko et Denis Arcon. « ChemInform Abstract : Magnetic Properties of Transition-Metal Oxides : from Bulk to Nano ». ChemInform 42, n^o 42 (27 septembre 2011) : no. http://dx.doi.org/10.1002/chin.201142214.

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Turco, Rosa, Julien Haber, IgorYuranov, Vincenzo Russo, Elio Santacesaria et Lioubov Kiwi-Minsker. « Sintered metal fibers coated with transition metal oxides as structured catalysts for hydrogen peroxide decomposition ». Chemical Engineering and Processing : Process Intensification 73 (novembre 2013) : 16–22. http://dx.doi.org/10.1016/j.cep.2013.08.004.

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Kim, Minjeong, Jahun Koo, Minjeong Kang, Juah Song et Chunjoong Kim. « Research Trend in Rock Salt Structured High Entropy Cathode ». Ceramist 25, n^o 1 (31 mars 2022) : 90–103. http://dx.doi.org/10.31613/ceramist.2022.25.1.06.

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Development of lithium-ion rechargeable batteries with high energy storage capability are required in timely manner. Recently, it has been experimentally and computationally proven that oxides with the disordered rock salt structure can be charged and discharged in the Li-ion battery system. In particular, the high entropy disordered rock salt cathode has unique structure property, where both Li-ion and transition metal are randomly located on the cation sites. Such disordering in metal sites can migrate the Li-ion in a percolating way albeit with sluggish kinetics. Therefore, the high entropy disordered rock salt structure has attracted great attention due to its high energy density and stable structure. In this paper, we introduce a simple and effective strategy in the selection of transition metals for high entropy cathodes to achieve desired electrochemical properties.

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Allam, E. A., R. M. El-Sharkawy, Kh S. Shaaban, A. El-Taher, M. E. Mahmoud et Y. El Sayed. « Structural and thermal properties of nickel oxide nanoparticles doped cadmium zinc borate glasses : preparation and characterization ». Digest Journal of Nanomaterials and Biostructures 17, n^o 1 (janvier 2022) : 161–70. http://dx.doi.org/10.15251/djnb.2022.171.161.

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Nickel-doped cadmium zinc borate glass of various nickel oxide content was prepared as xNiO–20ZnO–60B2 O3 –(20-x) CdO (0≤x≤5 mol %), by the melt quenching method based on nano metal oxides. Both the zinc oxide nanoparticles (ZnO NPs) and cadmium oxide nanoparticles (CdO NPs) were prepared via the solution–combustion technique. Nickel oxide nanoparticles (NiO NPs) was synthesized by the combustion of Ni(OH)2 and boron oxide nanoparticles (B2 O3 NPs)was synthesized by the solid-state reaction method. The amorphous nature of these types of glass was confirmed using X-ray diffraction analysis (XRD). The morphology of nano-metal oxides was investigated via the scanning electron microscope (SEM). SEM imaging showed that the NiO NPs had a semi-spherical morphology, and that their average particle size was 22.17 nm. The Fourier-transform infrared spectroscopy’s (FTIR) spectral analysis was used to identify the structural units of these types of glass via deconvolution, in terms of multi-Gaussian fitting. Results proved that Ni 4+ plays an important role and a key to improve the formation of the BO4 network units. Finally, the high thermal stability and glass transition temperature of the prepared glass samples were increased by increasing the loading of NiO NPs from 0.0 mol % - 5.0 7k = mol % and this was established by using DTA.

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Poizot, P., S. Laruelle, S. Grugeon, L. Dupont et J.-M. Tarascon. « Nano-sized transition-metal oxides as negative-electrode materials for lithium-ion batteries ». Nature 407, n^o 6803 (septembre 2000) : 496–99. http://dx.doi.org/10.1038/35035045.

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Miller, Joel S. « Three-Dimensional Network-Structured Cyanide-Based Magnets ». MRS Bulletin 25, n^o 11 (novembre 2000) : 60–64. http://dx.doi.org/10.1557/mrs2000.225.

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Magnets based on metal oxides have been important for hundreds of years. Magnetite, Fe3O4, Co-doped γ-Fe2O3, and CrO2 are important examples. The oxide (O2-) bridge between the magnetic metal ions has filled p orbitals (Figure 1a) that provide the pathway for strong spin coupling. Albeit with twice as many atoms, cyanide (C≡N−) can bridge between two metal ions via its pair of empty antibonding orbitals (Figure 1b) and filled nonbonding orbitals. Even prior to a detailed understanding of either their composition or structure, magnetic ordering of several cyanide complexes, although at low temperature, was noted. The differing atoms at each end of the cyanide ion have different binding affinities to metal ions, and simple coordination compounds, for example, [FeII(CN)6]2− (ferrocyanide), with alkali cations can easily be made. Replacement of the alkali cations with transition-metal cations affords insoluble materials, for example FeIII4[FeII(CN)6]3 (Prussian blue). Prussian blue has been used as a pigment and as an electrochromic and electrocatalyst material. The structure of Prussian blue was elucidated to be cubic (isotropic) with ⟶FeII⟵C≡N⟶FeIII⟵N≡C⟶FeII⟵ linkages along all three crystallographic directions (Figure 2). The FeII … FeIII separation is ∼5 Å. However, based on the composition, this is an idealized structure, as one FeII site per unit cell is missing. Water fills the vacant sites as well as the channels present in the structure. Due to the structural defects, it has been a challenge to grow single crystals.

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Stegemann, Bert, Matthias Klemm, Siegfried Horn et Mathias Woydt. « Switching adhesion forces by crossing the metal–insulator transition in Magnéli-type vanadium oxide crystals ». Beilstein Journal of Nanotechnology 2 (27 janvier 2011) : 59–65. http://dx.doi.org/10.3762/bjnano.2.8.

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Magnéli-type vanadium oxides form the homologous series V n O2 n -1 and exhibit a temperature-induced, reversible metal–insulator first order phase transition (MIT). We studied the change of the adhesion force across the transition temperature between the cleavage planes of various vanadium oxide Magnéli phases (n = 3 … 7) and spherical titanium atomic force microscope (AFM) tips by systematic force–distance measurements with a variable-temperature AFM under ultrahigh vacuum conditions (UHV). The results show, for all investigated samples, that crossing the transition temperatures leads to a distinct change of the adhesion force. Low adhesion corresponds consistently to the metallic state. Accordingly, the ability to modify the electronic structure of the vanadium Magnéli phases while maintaining composition, stoichiometry and crystallographic integrity, allows for relating frictional and electronic material properties at the nano scale. This behavior makes the vanadium Magnéli phases interesting candidates for technology, e.g., as intelligent devices or coatings where switching of adhesion or friction is desired.

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LUCOVSKY, GERALD. « PART II : CONDUCTION BAND-EDGE STATES ASSOCIATED WITH REMOVAL OF d-STATE DEGENERACIES BY THE STATIC JAHN-TELLER EFFECT ». International Journal of High Speed Electronics and Systems 16, n^o 01 (mars 2006) : 263–300. http://dx.doi.org/10.1142/s0129156406003643.

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X-ray absorption spectroscopy (XAS) is used to study band edge electronic structure of high-k transition metal (TM) and trivalent lanthanide rare earth (RE) oxide dielectrics. The lowest conduction band d*-states in nano-crystalline TiO 2, ZrO 2 and HfO 2 are correlated with features in the O K 1 edge, and transitions from occupied Ti 2p, Zr 3p and Hf 4p states to empty Ti 3d-, Zr 4d-, and Hf 5d-states, respectively. Optical band gaps, E opt , and conduction band offset energy with respect to Si , E B , scale monotonically with d-state energies of the TM/RE atoms. The multiplicity of d-state features in the Ti L 2,3 spectrum of TiO 2, and the O K 1 derivative spectra for ZrO 2 and HfO 2 indicate a complete removal of d-state degeneracies resulting from a static Jahn-Teller effect. Similar degeneracy removals are shown for complex nano-crystalline TM/RE oxides such as Zr and Hf titanates, and La , Gd and Dy scandates. XAS and band edge spectra indicate an additional band edge defect state assigned Jahn-Teller distortions at internal grain boundaries. These defect states are electronically active act as bulk traps in metal oxide semiconductor (MOS) devices, contributing to asymmetries in tunneling and Frenkel-Poole transport with important consequences for performance and reliability in advanced Si devices.

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Natarajan, Arunadevi, Kanchana Ponnuswamy et Kamatchi Ayyasamy. « Transition Metal Complexes of 3,5-Dihydroxy-2-naphthoic Acid and its Nano Metal Oxides : Synthesis and Characterization ». Asian Journal of Chemistry 29, n^o 8 (2017) : 1728–30. http://dx.doi.org/10.14233/ajchem.2017.20601.

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Anguraj, G., R. Ashok Kumar, C. Inmozhi, R. Uthrakumar, Mohamed S. Elshikh, Saeedah Musaed Almutairi et K. Kaviyarasu. « MnO2 Doped with Ag Nanoparticles and Their Applications in Antimicrobial and Photocatalytic Reactions ». Catalysts 13, n^o 2 (12 février 2023) : 397. http://dx.doi.org/10.3390/catal13020397.

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A wide range of nanoparticles have been produced for photocatalysis applications. Nonetheless, degrading organic dyes requires nanoparticles that are efficient and excellent. As a photocatalyst, pure manganese oxide (MnO2) was prepared via a sol–gel method using silver (Ag) nanoparticles of transition metal oxide. In addition to X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX), the crystal structure and elemental composition were analysed. According to XRD data, the transition metal of MnO2 oxide is highly pure and has a small crystallite size. The presence of functional groups was confirmed and clarified using Fourier-transform infrared spectra (FTIR). By irradiating the transition pure and doped MnO2 photocatalysts with visible light, the UV-vis, μ-Raman, and surface areas were determined. As a result, of using the photocatalysts with aqueous methylene blue (MB) solutions under visible light irradiation, the MnO2 doped with Ag nanoparticles demonstrated high degradation efficiencies and were utilised to establish heterogeneous photocatalysis dominance. In this paper, we demonstrate that the photocatalytic efficiency of transition metal oxides is exclusively determined by the particle size and surface area of nano-sized materials. Due to their high surface charge ratio and different surface orientations, have the highest photocatalytic efficiency. Generally, MnO2 doped with Ag nanoparticles is resistant to bacteria of both Gram-positive and Gram-negative types (B. sublittus and Escherichia coli). There is still a need for more research to be performed on reducing the toxicity of metal and metal oxide nanoparticles so that they can be used as an effective alternative to antibiotics and disinfectants, particularly for biomedical applications.

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Poizot, P., S. Laruelle, S. Grugeon, L. Dupont et J. M. Tarascon. « ChemInform Abstract : Nano-Sized Transition-Metal Oxides as Negative-Electrode Materials for Lithium-Ion Batteries. » ChemInform 32, n^o 3 (16 janvier 2001) : no. http://dx.doi.org/10.1002/chin.200103013.

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Felgueiras, Mariana B. S., João Restivo, Juliana P. S. Sousa, Manuel F. R. Pereira et Olívia S. G. P. Soares. « Copper Supported on Mesoporous Structured Catalysts for NO Reduction ». Catalysts 12, n^o 2 (28 janvier 2022) : 170. http://dx.doi.org/10.3390/catal12020170.

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Nitrogen oxides (NOx) are one of the pollutants of greatest concern in terms of atmospheric contamination and, consequently, human health. The main objective of this work, is the synthesis of structured carbon catalysts, introducing on their surface metals and nitrogen groups, catalytically active in NO reduction. Structured catalysts represent an attractive alternative to powder catalysts because they have better thermal stability and lower pressure drop. The catalysts were synthesized by coating a melamine foam using precursor solutions of carbon xerogels with and without nitrogen (using melamine and urea as precursors), and impregnated with transition metals (Fe, Ni and Cu). The introduction of nitrogen and metals modified the textural properties of the materials. Samples synthesized with melamine presented the highest amount of nitrogen, while the highest content of copper, found to be the most active transition metal for NO reduction, was found in structured catalysts impregnated with urea. The presence of transition metals in catalysts is essential for the reduction of NO to N2 and the introduction of nitrogenous precursors makes this evident. The synthesis and application of carbon-supported structured catalysts containing transition metals for NO reduction is demonstrated in this work for the first time, as well as the study of the factors influencing their performance.

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Jana, Malay, Anjan Sil et Subrata Ray. « Influence of Melting of Transition Metal Oxides on the Morphology of Carbon Nanostructures ». Advanced Materials Research 585 (novembre 2012) : 159–63. http://dx.doi.org/10.4028/www.scientific.net/amr.585.159.

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Different types of carbon nanostructure materials have been grown on nano-sized transition metal oxide based catalyst particles by catalytic chemical vapour deposition. The present investigation reveals an important role of melting or surface melting of oxide catalysts for the growth of carbon nanostructure materials. In the reducing environment prevailing during the growth of nanostructures, oxide catalysts are reduced to metals, which may act as a template for the growth of carbon nanostructure materials. Flow rate of acetylene gas is crucial in catalyzing the growth, as high flow rate of acetylene may cover the catalyst particles with a layer of decomposed carbon, rendering the particles incapable of playing the role of catalyst. The size of the catalyst and the extent of melting, determined primarily by the extent of doping, are important in deciding whether the conditions are favourable for the growth of multi walled carbon nanotube, nanofiber or other nanostructures. Smaller particle size and low doping level favour the growth of multi walled carbon nanotube while growth of nanofiber is commonly observed with larger particles and higher doping level. The size (i.e. diameter) of the nanostructures growing around the catalyst is proportional to the particle size of the catalyst.

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Wang, Chih Ming, Kuo Sheng Kao, Da Long Cheng, Chien Chuan Cheng, Po Tsung Hsieh, Shih Yuan Lin, Tai Yu Shih et Chih Yu Wen. « Electrochromic Properties of Nano-Columnar Nickel Oxide ». Materials Science Forum 654-656 (juin 2010) : 1904–7. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1904.

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Electrochromic properties of transition metal oxides had much attention in recent years. The electrochromic thin films can be assembly as electrochromic devices (ECDs) and then used for applications in devices such as mirrors, panels and smart windows. A kind of complementary ECD is popular in resent years. Therefore, a specific investigation on nickel oxide (NiO) electrochromic properties is completed in this study. The crystalline structure of the NiO films was analyzed using XRD (PANalytical X’Pert PRO) with Cu-Kα radiation. The atmosphere of oxygen concentration increasing has changed the NiO films crystalline from (200) to (111). The thicknesses and surface microstructures of the NiO films were investigated using a scanning electron microscope (SEM, Philips/FEI XL40 FEG). It is observed that films are relatively smooth deposited without oxygen. The characterization of the electrochromic properties was carried out in a two-electrode cell with an electrochemical analyzer (CHI 611B). The NiOx changes the transmittance of NiO films in the wavelength range of 300-1500 nm and the color of the film changes from transparent to brown. The nano-crack exhibits in the NiO film did enhance the electrochromic properties.

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Abdul Karim, Hussein Jamal, et Ghuson H. Mohammed. « Effect of Transition Metal Dopant on the Electrical Properties of ZnO-TiO2 Films Prepared by PLD Technique ». Iraqi Journal of Physics (IJP) 19, n^o 49 (18 mai 2021) : 75–81. http://dx.doi.org/10.30723/ijp.v19i49.608.

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In this article, the influence of group nano transition metal oxides such as {(MnO2), (Fe2O3) and (CuO)} thin films on the (ZnO-TiO2) electric characteristics have been analyzed. The prepared films deposited on glass substrate laser Nd-YAG with wavelength (ℷ =1064 nm) ,energy of (800mJ) and number of shots (400). The density of the film was found to be (200 nm) at room temperature (RT) and annealing temperature (573K).Using DC Conductivity and Hall Effect, we obtained the electrical properties of the films. The DC Conductivity shows that that the activation energies decrease while the σRT at annealing temperature with different elements increases the formation of mixed oxides. The Hall effect, the electrical properties of the films were described. It was observed through Hall Effect measurements that the films loaded vectors of the shape N and the type P.

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Thankaian, Regin Das, Meena Muthukrishnan, Senthil Muthu Kumar Thiagamani, Suchart Siengchin et Sanjay Manvikere Rangappa. « Impact of metal doping and codoping on the electrical and optical behavior of tin oxide nano particles ». Nanomaterials and Energy 11, n^o 3-4 (1 décembre 2022) : 1–8. http://dx.doi.org/10.1680/jnaen.23.00010.

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Metal oxide semiconductors (MOS) with distinctive optical and electrical properties are required by the modern electronics industry. In this research it was found that doping of transition and rare-earth metals is suitable for tuning the optical bandgap and dielectric parameters of SnO2 Nanoparticles to meet the requirement for high conductive semiconductors Via one-step hydrothermal synthesis Doping of Sm causes SnO2NP to have a narrower bandgap (2.54 eV) than pure SnO2NPs (3.36 eV), and increased conductivity at higher frequencies and temperature, which is crucial for the potential applications like light-emitting diodes, biological labels, optoelectronic devices, and other technologies. The particle size of the doped and co-doped sample was found to be smaller than pure SnO2 which effectively pronounced the quantum confinement effect in these metal oxides. Co-doping of Sm-Cu ions in the SnO2 lattice was done for the first time to increase the dielectric strength, with absorption shift towards visible blue region suggest the use of this particular sample for photocatalytic application.

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Lindenthal, Lorenz, Raffael Rameshan, Harald Summerer, Thomas Ruh, Janko Popovic, Andreas Nenning, Stefan Löffler, Alexander Karl Opitz, Peter Blaha et Christoph Rameshan. « Modifying the Surface Structure of Perovskite-Based Catalysts by Nanoparticle Exsolution ». Catalysts 10, n^o 3 (1 mars 2020) : 268. http://dx.doi.org/10.3390/catal10030268.

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In heterogeneous catalysis, surfaces decorated with uniformly dispersed, catalytically-active (nano)particles are a key requirement for excellent performance. Beside standard catalyst preparation routines—with limitations in controlling catalyst surface structure (i.e., particle size distribution or dispersion)—we present here a novel time efficient route to precisely tailor catalyst surface morphology and composition of perovskites. Perovskite-type oxides of nominal composition ABO3 with transition metal cations on the B-site can exsolve the B-site transition metal upon controlled reduction. In this exsolution process, the transition metal emerges from the oxide lattice and migrates to the surface where it forms catalytically active nanoparticles. Doping the B-site with reducible and catalytically highly active elements, offers the opportunity of tailoring properties of exsolution catalysts. Here, we present the synthesis of two novel perovskite catalysts Nd0.6Ca0.4FeO3-δ and Nd0.6Ca0.4Fe0.9Co0.1O3-δ with characterisation by (in situ) XRD, SEM/TEM and XPS, supported by theory (DFT+U). Fe nanoparticle formation was observed for Nd0.6Ca0.4FeO3-δ. In comparison, B site cobalt doping leads, already at lower reduction temperatures, to formation of finely dispersed Co nanoparticles on the surface. These novel perovskite-type catalysts are highly promising for applications in chemical energy conversion. First measurements revealed that exsolved Co nanoparticles significantly improve the catalytic activity for CO2 activation via reverse water gas shift reaction.

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Kumta, Prashant, Oleg Velikokhatnyi et Ramalinga Kuruba. « (Invited) From Lithiated Transition Metal Oxide to Silicon and Lithium-Sulfur Systems : An Evolution of Electrochemically Active Materials ». ECS Meeting Abstracts MA2022-02, n^o 2 (9 octobre 2022) : 138. http://dx.doi.org/10.1149/ma2022-022138mtgabs.

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Energy storage is vital for driving an energy independent world economy that is currently largely dependent on exploiting natural reserves supplemented by oil and gas exports. The field of Li-ion batteries continues to witness burgeoning progress since the commercialization of the first Li-ion battery (LIB) by Sony in 1991, and is at present, clearly the flagship rechargeable battery system. Correspondingly, enormous progress is seen in cathodes, electrolytes as well as anodes [1]. New materials have continuously evolved. Lithiated transition metal oxides despite advances in various systems, are still the flagship cathodes of choice relying on ubiquitous intercalation chemistries. Newer chemistries exploiting alloying and Zintl phase formation focusing on silicon and tin as alternative anodes have also evolved in the last two decades. Similarly, there is tremendous research in the area of alternative energy storage systems beyond lithium-ion intercalation chemistry. Lithium-sulfur batteries (LSB) and Li metal anodes have putatively emerged at the forefront and are the spotlight of increased research activity in recent years. All these systems are unfortunately, plagued by intransigent inferior electronic conductivity, Li-ion conductivity, voltage-specific phase transition related kinetic limitations accompanied with ensuing chemical, physical, and electrochemical challenges. Nano-engineered approaches aided by concomitant progress in science and technology of synthetic and analytical chemistry of advanced materials appear primed for overcoming these hurdles. We initiated work introducing solution-based chemical synthesis strategies for generating nanostructured lithiated transition metal oxides, including anti-site defect-free LiNiO2[2,3]. This work then transitioned into alternative anodes[4] and presently into the Li-S systems holding much promise, albeit major challenges remain to be overcome. We have thus far, implemented dynamic theoretical and experimental strategies to develop engineered electronic and Li-ion conducting nanomaterials showing considerable promise as supporting components augmenting the performance and overcoming many of the limitations affecting these systems. Additionally, we have developed several approaches utilizing nanoscale droplets, nanoparticles, hollow silicon nanotubes (h-SiNTs), cost-effective template derived nanoscale morphologies, scribable and flexible hetero-structured Si architectures, displaying impressive capacities of ~3000 mAh/g with sustained cyclability and high-rate capability in Si anodes [4]. Electrochemical approaches were also developed creating binder-less Si-based thin film anodes with considerable promise. Similarly, engineering approaches were implemented for generating sulfur cathodes in LSBs exploiting the tailored attributes of inorganic, nanocomposite, tethered, and polymeric lithium ion conductors (LIC) coupled with chemically linked complex framework materials (CFM) based matrices for encapsulating S along with novel fine yarn-like and tethered S architectures yielding 5.5 mAh/cm2 – 12 mAh/cm2 areal capacity and ~1200 mAh/g specific capacity with S loadings as high as 20 mg/cm2 displaying ~250 cycles cycling stability [5, 6]. Single layer pouch cells exhibiting 180-200 Wh/kg were also demonstrated. Developing scalable economic approaches, however, remain a key challenge. Engineering strategies were also developed for identifying new Li metal alloy anodes preventing and eliminating dendrite formation. These systems serve as alternative safe anodes to Li metal. This presentation will thus provide an overview of the above systems. Similarly, insights into the promising future in generating tailored functional engineered systems in the rapidly evolving digitally savvy era of the 21st century will also be presented. Finally, the prospects of these systems offering a pathway to potentially achieving energy independence in the near future will also be outlined. References Wang, P.N. Kumta, et al. ACS Nano (2011). C-C. Chang, P.N. Kumta et al. J. Electrochemical Society 147 (2000). C. Chang, P.N. Kumta et al. J. Power Sources 75 (1998). Gattu, P.N. Kumta et al. Nano Research (2017). M. Shanthi, P.N. Kumta et al. Electrochimica Acta (2017). M. Shanthi, P.N. Kumta et al. Applied Energy Materials (2018).

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Almaieli, Latifah Mohammed Ali, Mai M. Khalaf, Mohamed Gouda, Sultan Alhayyani, Manal F. Abou Taleb et Hany M. Abd El-Lateef. « Titanium Dioxide/Chromium Oxide/Graphene Oxide Doped into Cellulose Acetate for Medical Applications ». Polymers 15, n^o 3 (17 janvier 2023) : 485. http://dx.doi.org/10.3390/polym15030485.

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Wound dressings have been designed based on cellulose acetate encapsulated with different concentrations of chromium oxide (Cr2O3) and titanium oxide (TiO2) with/without graphene oxide (GO). This study comprises the structural, morphological, optical, thermal, and biological behavior of chromium oxide/titanium dioxide/graphene oxide-integrated cellulose acetate (CA) films. The CA-based film bond formation was introduced by functional group analysis via Fourier transform infrared (FTIR) spectroscopy. The fabricated Cr2O3/TiO2/GO@CA film SEM micrographs demonstrate transition metal oxides Cr2O3 and TiO2 on a nano-scale. The TiO2@CA shows the lowest contact angle with 30°. Optically, the refractive index increases from 1.76 for CA to 2.14 for the TiO2@CA film. Moreover, normal lung cells (A138) growth examination in a function of Cr2O3/TiO2/GO@CA film concentration is conducted, introducing 93.46% with the usage of 4.9 µg/mL. The resulting data showed a promising wound-healing behavior of the CA-based films.

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Horibe, Yoichi, et Shigeo Mori. « Fabrications and Characterizations of Checkerboard-type Nano-structure Utilized by Phase Separation in Transition Metal Oxides ». Materia Japan 57, n^o 6 (2018) : 271–76. http://dx.doi.org/10.2320/materia.57.271.

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Hattori, Azusa N., Ai I. Osaka, Ken Hattori, Yasuhisa Naitoh, Hisashi Shima, Hiroyuki Akinaga et Hidekazu Tanaka. « Investigation of Statistical Metal-Insulator Transition Properties of Electronic Domains in Spatially Confined VO2 Nanostructure ». Crystals 10, n^o 8 (22 juillet 2020) : 631. http://dx.doi.org/10.3390/cryst10080631.

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Functional oxides with strongly correlated electron systems, such as vanadium dioxide, manganite, and so on, show a metal-insulator transition and an insulator-metal transition (MIT and IMT) with a change in conductivity of several orders of magnitude. Since the discovery of phase separation during transition processes, many researchers have been trying to capture a nanoscale electronic domain and investigate its exotic properties. To understand the exotic properties of the nanoscale electronic domain, we studied the MIT and IMT properties for the VO2 electronic domains confined into a 20 nm length scale. The confined domains in VO2 exhibited an intrinsic first-order MIT and IMT with an unusually steep single-step change in the temperature dependent resistivity (R-T) curve. The investigation of the temperature-sweep-rate dependent MIT and IMT properties revealed the statistical transition behavior among the domains. These results are the first demonstration approaching the transition dynamics: the competition between the phase-transition kinetics and experimental temperature-sweep-rate in a nano scale. We proposed a statistical transition model to describe the correlation between the domain behavior and the observable R-T curve, which connect the progression of the MIT and IMT from the macroscopic to microscopic viewpoints.

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Shaikh, Aqsa, Muddassir Ali Memon et M. Wasim Akhtar. « Effect of temperature on the polymorphs of titania (TiO2) developed by sol-gel and hydrothermal processes for thin film uses ». Mehran University Research Journal of Engineering and Technology 41, n^o 3 (1 juillet 2022) : 161–67. http://dx.doi.org/10.22581/muet1982.2203.16.

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Titanium dioxide (TiO2) has been utilized for photovoltaic devices mostly as electron selective ply. Most of the transition metal complexes like TiO2 possess wider band gap to predominant relying on morphology of nano-particles. Most of the metal oxides possess excellent ability of harvesting extensive part of sunlight. This study reports, synthesis of TiO2 by using two different techniques i.e., sol-gel and hydrothermal. Later nano films was applied on fluorine doped tin oxide glass through spin coating at ambient temperature. Particles of TiO2 were synthesized at different temperatures however rest of the variable like solvent, concentration and amount of precursor were static. Nanoparticles of anatase titania synthesized through sol-gel had higher crystallinity. Particle size of synthesized particles was 12.2 nm at 25o C. Subsequently particles produced through hydrothermal procedure were large with an average particle size of 16 nm at 100o C. FTIR further confirmed the synthesis of anatase titania at 400-800 cm-1. X-ray diffraction technique also confirmed the synthesis of titania at 25.3o ,38.0o, 47o, 54.5o, 62.7o and 78o . UV-visible spectroscopy was performed to analyze optical properties exhibiting peak absorbance at 424 nm. This synthesized TiO2 anatase is extensively used for photovoltaic application.

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Liu, Xingmei, Yuwei Wang, Liquan Fan, Weichao Zhang, Weiyan Cao, Xianxin Han, Xijun Liu et Hongge Jia. « Sm0.5Sr0.5Co1−xNixO3−δ—A Novel Bifunctional Electrocatalyst for Oxygen Reduction/Evolution Reactions ». Molecules 27, n^o 4 (14 février 2022) : 1263. http://dx.doi.org/10.3390/molecules27041263.

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The development of non-precious metal catalysts with excellent bifunctional activities is significant for air–metal batteries. ABO3-type perovskite oxides can improve their catalytic activity and electronic conductivity by doping transition metal elements at B sites. Here, we develop a novel Sm0.5Sr0.5Co1−xNixO3−δ (SSCN) nanofiber-structured electrocatalyst. In 0.1 M KOH electrolyte solution, Sm0.5Sr0.5Co0.8Ni0.2O3−δ (SSCN82) with the optimal Co: Ni molar ratio exhibits good electrocatalytic activity for OER/ORR, affording a low onset potential of 1.39 V, a slight Tafel slope of 123.8 mV dec−1, and a current density of 6.01 mA cm−2 at 1.8 V, and the ORR reaction process was four-electron reaction pathway. Combining the morphological characteristic of SSCN nanofibers with the synergistic effect of cobalt and nickel with a suitable molar ratio is beneficial to improving the catalytic activity of SSCN perovskite oxides. SSCN82 exhibits good bi-functional catalytic performance and electrochemical double-layer capacitance.

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Arunadevi, N., et S. Vairam. « 3-Hydroxy-2-naphthoate Complexes of Transition Metals with Hydrazine - Preparation, Spectroscopic and Thermal Studies ». E-Journal of Chemistry 6, s1 (2009) : S413—S421. http://dx.doi.org/10.1155/2009/937216.

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Reaction of hydrazine and 3-hydroxy-2-naphthoic acid with some transition metal ions forms two types of complexes: (i) [M(N2H4){C10H6(3-O)(2-COO)(H2O)2] where M=Ni, Co, Cd and Zn, at pH 9 and (ii) [M(N2H5)2{C10H6(3-O)(2-COO)}2].xH2O where M=Ni & x =1; M=Co, Cd, Mn & x=3; and M=Zn, Cu & x =0 at pH 4. Analytical data confirms the compositions of the complexes. The acid shows dianionic nature in these complexes. The magnetic moments and electronic spectra suggest the geometry of the complexes. IR data indicates the nature of hydrazine and presence of water in the complexes. Simultaneous TG-DTA studies shows different thermal degradation patterns for the two types of complexes. The first type shows formation of no stable intermediates whereas the second type shows the respective metal hydroxy naphthoate intermediates. The final products in both the types are found to be metal oxides of nano size. XRD patterns show isomorphism among the complexes with similar molecular formulae.

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Kong, Yueyue, Ranran Jiao, Suyuan Zeng, Chuansheng Cui, Haibo Li, Shuling Xu et Lei Wang. « Study on the Synthesis of Mn3O4 Nanooctahedrons and Their Performance for Lithium Ion Batteries ». Nanomaterials 10, n^o 2 (20 février 2020) : 367. http://dx.doi.org/10.3390/nano10020367.

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Among the transition metal oxides, the Mn3O4 nanostructure possesses high theoretical specific capacity and lower operating voltage. However, the low electrical conductivity of Mn3O4 decreases its specific capacity and restricts its application in the energy conversion and energy storage. In this work, well-shaped, octahedron-like Mn3O4 nanocrystals were prepared by one-step hydrothermal reduction method. Field emission scanning electron microscope, energy dispersive spectrometer, X-ray diffractometer, X-ray photoelectron spectrometer, high resolution transmission electron microscopy, and Fourier transformation infrared spectrometer were applied to characterize the morphology, the structure, and the composition of formed product. The growth mechanism of Mn3O4 nano-octahedron was studied. Cyclic voltammograms, galvanostatic charge–discharge, electrochemical impedance spectroscopy, and rate performance were used to study the electrochemical properties of obtained samples. The experimental results indicate that the component of initial reactants can influence the morphology and composition of the formed manganese oxide. At the current density of 1.0 A g−1, the discharge specific capacity of as-prepared Mn3O4 nano-octahedrons maintains at about 450 mAh g−1 after 300 cycles. This work proves that the formed Mn3O4 nano-octahedrons possess an excellent reversibility and display promising electrochemical properties for the preparation of lithium-ion batteries.

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Kotobuki, Masashi. « Preparation of Nano-Particles of Transition Metal Oxides Using Ball-Milling and its Application for Lithium Battery ». Advanced Materials Research 622-623 (décembre 2012) : 955–58. http://dx.doi.org/10.4028/www.scientific.net/amr.622-623.955.

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Lithium ion battery prefers an electrode consist of small particles so as to allow giving short Li+ diffusion pathway. In order to obtain small particles of LiCoO2, which has been commonly used as cathode for lithium battery, the ball-milling is applied to LiCoO2 prepared through a sol-gel method. By the ball-milling, the particle size of LiCoO2 can be reduced from 400 to 250 nm. The discharge capacity of milled LiCoO2 under high current density of 5C is about 100 mA h g-1, that is much higher than non-milled LiCoO2 (60 mA h g-1). It is concluded that the small LiCoO2 prepared by the ball-milling possess superior performance due to short Li+ diffusion length.

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Pal, Pratibha, Jyh-Ming Ting, Shivani Agarwal, Takayuki Ichikawa et Ankur Jain. « The Catalytic Role of D-block Elements and Their Compounds for Improving Sorption Kinetics of Hydride Materials : A Review ». Reactions 2, n^o 3 (18 septembre 2021) : 333–64. http://dx.doi.org/10.3390/reactions2030022.

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The goal of finding efficient and safe hydrogen storage material motivated researchers to develop several materials to fulfil the demand of the U.S. Department of Energy (DOE). In the past few years, several metal hydrides, complex hydrides such as borohydrides and alanates, have been researched and found efficient due to their high gravimetric and volumetric density. However, the development of these materials is still limited by their high thermodynamic stability and sluggish kinetics. One of the methods to improve the kinetics is to use catalysts. Among the known catalysts for this purpose, transition metals and their compounds are known as the leading contender. The present article reviews the d-block transition metals including Ni, Co, V, Ti, Fe and Nb as catalysts to boost up the kinetics of several hydride systems. Various binary and ternary metal oxides, halides and their combinations, porous structured hybrid designs and metal-based Mxenes have been discussed as catalysts to enhance the de/rehydrogenation kinetics and cycling performance of hydrogen storage systems.

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Atanassov, Plamen, Yechuan Chen, Tristan Asset, Yuanchao Liu, Eamonn Murphy et Ivana Matanovic. « (Keynote) Mechanistic Understanding of the Activity of Atomically Dispersed Transition Metal-Nitrogen-Carbon Catalysts in Oxygen, Carbon Dioxide or Nitrogen Electro-Reduction ». ECS Meeting Abstracts MA2022-01, n^o 49 (7 juillet 2022) : 2077. http://dx.doi.org/10.1149/ma2022-01492077mtgabs.

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Over the last two decades, platinum group metal-free (PGM-free) catalysts are attracting increasing attention and finding applications in several important process across many electrochemical energy technologies. Among those PGM-free materials, atomically dispersed (AD) transition metal-nitrogen-carbon (M-N-C) catalysts are gaining exceptional popularity as they demonstrate very high (for this class of materials) activity in oxygen reduction reaction (ORR)1 and are the only cathode catalysts suitable for both proton exchange membrane fuel cells (PEMFC) and alkaline, including anion/hydroxyl exchange membrane fuel cells (AFC, AEMFC/HEMFC). Over the last few years, M-N-C catalysts have shown promising activity in carbon dioxide reduction reaction (CO2RR).2 In this case, varying the transition metal in M-N-Cs opens routes for controlling the selectivity towards a list of C1 and C2 products. There are recent reports on catalytic activity of AD M-N-C materials in direct electro-reduction of molecular nitrogen (N2RR) or reactions of reduction of nitrates, nitrites or various nitrogen oxides (NOx). We have systematically investigated all these processes having as a base the M-N-C catalysts synthesized by sacrificial support method (SSM) – a hard template approach with transition metal salt and charge-transfer organic salt (nicarbazin) mixed by ball-milling, pyrolyzed at high temperature in inert atmosphere and then etched in HF after cooling. In most cases a secondary (similar) pyrolysis was performed to refine the material and ensure its AD character. The makeup and structure of the active site/sites of the AD M-N0C electrocatalysts, including geometry (coordination) and chemistry (composition and oxidation state) remain contentious to this day. There is an emerging agreement however, that the transition metal (at least for the 2nd row transitions meals) is immediately associated with (liganded by) the nitrogen functionalities, displayed on the surface if the carbonaceous substrate. It is almost universally accepted that N-coordinated AD transition metal ions, either as in-plane or edge-type defect in “graphene” sheet, are the main/principal active sites. This is often combined with a broadly accepted hypothesis that micro-porous surface area plays a critical role forming edge-type, intercalational active sites while meso-porous interface is most-likely associated with the in-plane, substitutional AD metal sites. Candidate structures participating in reativity towards O2, CO2 or nitrogen species include a list of nitrogen-containg and oxygen-containng moeties in the carbonaceous matrix. The carbon itself displays various degrees of graphitization, depending on the transition metal used in M-N-C synthesis. Additional complexity in this calss of caralysts study comes from the fact that many samples are not strictly AD materials. They often contain incorporated metal nano-particles, corresponding (native) oxides and/or carbides and nitrides (oxocabides and oxonitrides have been observed as well).These “unrefined” M-N-C materials are often used in practice and the corresponding nano-particle components of the de-facto nanocomposites do alter substantially the reactivity and selectivity of the catalysts in all these electro-reduction reactions. This talk discusses the mechanistic aspects of M-N-C catalysts in ORR, CO2RR, N2RR and electroreduction of nitrogen-containing oxo-species, obtained when cross-referencing electrochemical activity results obtained in rotating disk and rotating ring-disk electrodes setting (RDE/RRDE) with those observed in near-ambient pressure X-ray photo-electron spectroscopy (NAP-XPS) and supported by density functional theory calculations of the reagents adsorption on AD transition metal or nitrogen- or oxygen-containing moieties from the carbonaceous matrix of the M-N-Cs. The later are of particular importance as significant reactivity has been observed for most of those processes when metal-free, nitrogen-doped carbon (N-C) catalysts are used.3 We will present a case that outlines the reactivity of M-N-C in those important electro-reduction reactions in terms of (i) role of the AD transition metal, (ii) role of the surface N-groups as co-catalysts/alternative sites (iii) role of surface oxides as co-catalysts or hydrophilic/hydrophobic properties descriptor, the last being also critically dependent on morphology.4 References: T. Asset and P. Atanassov, Joule, 2020, 4, 33. T. Asset, S.T. Garcia, S. Herrera, N. Andersen, Y. Chen, E.J. Peterson, I. Matanovic, K.Artyushkova, J. Lee, S.D. Minteer,S. Dai, X. Pan, K. Chavan, S. Calabrese Bartonand P. Atanassov, ACS Catalysis, 2019, 9, 7668 D. Hursán, A. Samu,K. Artyushkova,T. Asset, P. Atanassov and C. Janáky, Joule, 2019, 3 1719 Y. Huang, Y. Chen, M. Xu, T. Asset, P. Tieu, A. Gili, D. Kulkarni, V. de Andrade, F. de Carlo, H. S. Barnard, A. Doran, D. Y. Parkinson, X. Pan, P. Atanassov, and I. Zenyuk, Materials Today, 2021, 47, 53.

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Karuppiah, Chelladurai, Balamurugan Thirumalraj, Srinivasan Alagar, Shakkthivel Piraman, Ying-Jeng Jame Li et Chun-Chen Yang. « Solid-State Ball-Milling of Co3O4 Nano/Microspheres and Carbon Black Endorsed LaMnO3 Perovskite Catalyst for Bifunctional Oxygen Electrocatalysis ». Catalysts 11, n^o 1 (7 janvier 2021) : 76. http://dx.doi.org/10.3390/catal11010076.

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Developing a highly stable and non-precious, low-cost, bifunctional electrocatalyst is essential for energy storage and energy conversion devices due to the increasing demand from the consumers. Therefore, the fabrication of a bifunctional electrocatalyst is an emerging focus for the promotion and dissemination of energy storage/conversion devices. Spinel and perovskite transition metal oxides have been widely explored as efficient bifunctional electrocatalysts to replace the noble metals in fuel cell and metal-air batteries. In this work, we developed a bifunctional catalyst for oxygen reduction and oxygen evolution reaction (ORR/OER) study using the mechanochemical route coupling of cobalt oxide nano/microspheres and carbon black particles incorporated lanthanum manganite perovskite (LaMnO3@C-Co3O4) composite. It was synthesized through a simple and less-time consuming solid-state ball-milling method. The synthesized LaMnO3@C-Co3O4 composite was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction spectroscopy, and micro-Raman spectroscopy techniques. The electrocatalysis results showed excellent electrochemical activity towards ORR/OER kinetics using LaMnO3@C-Co3O4 catalyst, as compared with Pt/C, bare LaMnO3@C, and LaMnO3@C-RuO2 catalysts. The observed results suggested that the newly developed LaMnO3@C-Co3O4 electrocatalyst can be used as a potential candidate for air-cathodes in fuel cell and metal-air batteries.

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Karuppiah, Chelladurai, Balamurugan Thirumalraj, Srinivasan Alagar, Shakkthivel Piraman, Ying-Jeng Jame Li et Chun-Chen Yang. « Solid-State Ball-Milling of Co3O4 Nano/Microspheres and Carbon Black Endorsed LaMnO3 Perovskite Catalyst for Bifunctional Oxygen Electrocatalysis ». Catalysts 11, n^o 1 (7 janvier 2021) : 76. http://dx.doi.org/10.3390/catal11010076.

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Developing a highly stable and non-precious, low-cost, bifunctional electrocatalyst is essential for energy storage and energy conversion devices due to the increasing demand from the consumers. Therefore, the fabrication of a bifunctional electrocatalyst is an emerging focus for the promotion and dissemination of energy storage/conversion devices. Spinel and perovskite transition metal oxides have been widely explored as efficient bifunctional electrocatalysts to replace the noble metals in fuel cell and metal-air batteries. In this work, we developed a bifunctional catalyst for oxygen reduction and oxygen evolution reaction (ORR/OER) study using the mechanochemical route coupling of cobalt oxide nano/microspheres and carbon black particles incorporated lanthanum manganite perovskite (LaMnO3@C-Co3O4) composite. It was synthesized through a simple and less-time consuming solid-state ball-milling method. The synthesized LaMnO3@C-Co3O4 composite was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction spectroscopy, and micro-Raman spectroscopy techniques. The electrocatalysis results showed excellent electrochemical activity towards ORR/OER kinetics using LaMnO3@C-Co3O4 catalyst, as compared with Pt/C, bare LaMnO3@C, and LaMnO3@C-RuO2 catalysts. The observed results suggested that the newly developed LaMnO3@C-Co3O4 electrocatalyst can be used as a potential candidate for air-cathodes in fuel cell and metal-air batteries.

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Liu, Hongfei. « Recent Progress in Atomic Layer Deposition of Multifunctional Oxides and Two-Dimensional Transition Metal Dichalcogenides ». Journal of Molecular and Engineering Materials 04, n^o 04 (décembre 2016) : 1640010. http://dx.doi.org/10.1142/s2251237316400104.

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Atomic layer deposition (ALD) has long been developed for conformal coating thin films on planar surfaces and complex structured substrates based on its unique sequential process and self-limiting surface chemistry. In general, the coated thin films can be dielectrics, semiconductors, conductors, metals, etc., while the targeted surface can vary from those of particles, wires, to deep pores, through holes, and so on. The ALD coating technique, itself, was developed from gas-phase chemical vapor deposition, but now it has been extended even to liquid phase coating/growth. Because the thickness of ALD growth is controlled in atomic level ([Formula: see text]0.1[Formula: see text]nm), it has recently been employed for producing two-dimensional (2D) materials, typically semiconducting nanosheets of transition metal dichalcogenides (TMDCs). In this paper, we briefly introduce recent progress in ALD of multifunctional oxides and 2D TMDCs with the focus being placed on suitable ALD precursors and their ALD processes (for both binary compounds and ternary alloys), highlighting the remaining challenges and promising potentials.

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Mladenov, Valeri. « A Unified and Open LTSPICE Memristor Model Library ». Electronics 10, n^o 13 (2 juillet 2021) : 1594. http://dx.doi.org/10.3390/electronics10131594.

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In this paper, a unified and open linear technology simulation program with integrated circuit emphasis (LTSPICE) memristor library is proposed. It is suitable for the analysis, design, and comparison of the basic memristors and memristor-based circuits. The library could be freely used and expanded with new LTSPICE memristor models. The main existing standard memristor models and several enhanced and modified models based on transition metal oxides such as titanium dioxide, hafnium dioxide, and tantalum oxide are included in the library. LTSPICE is one of the best software for analysis and design of electronic schemes. It is an easy to use, widespread, and free product with very good convergence. Memristors have been under intensive analysis in recent years due to their nano-dimensions, low power consumption, high switching speed, and good compatibility with traditional complementary metal oxide semiconductor (CMOS) technology. In this work, their behavior and potential applications in artificial neural networks, reconfigurable schemes, and memory crossbars are investigated using the considered memristor models in the proposed LTSPICE library. Furthermore, a detailed comparison of the presented LTSPICE memristor model library is conducted and related to specific criteria, such as switching speed, operating frequencies, nonlinear ionic drift representation, boundary effects, switching modes, and others.

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Siddhapara, kirit Kumar. « Effect of Transition Metal (Fe, Co) Ion Doping on TiO₂ Nano Particles. » ECS Meeting Abstracts MA2022-02, n^o 38 (9 octobre 2022) : 2424. http://dx.doi.org/10.1149/ma2022-02382424mtgabs.

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Keywords: Growth from solution, Nanomaterials, Oxides, Photocatalytic, Sol-Gel method, DMS. Abstract. we report the growth of [Fe, Co]xTiO2 (x=0.01, 0.02 & 0.04) Nano quantum dots prepared by Sol-Gel technique, followed by freeze-drying treatment at -30°C temperature for 12hrs. The obtained Gel was thermally treated at different temperature like 200,400,600, 800°C. The crystalline size of 4 to 40 nm is achieved. X-ray diffraction pattern of samples show anatase phases of TiO2, up to 600°C. At 800°C, the phase is Rutile. Figure 1 shows the XRD patterns acquired from different samples heated at different temperatures. The diffraction peak at 25.22°, 25.49°and 25.6° observed from the XRD pattern of the Fe, Co doped TiO2 shows that the main crystal phase is anatase, and the peak at 27.47° indicates the presence of the rutile phase. All the peaks in the XRD patterns of the sample calcined at 200°C, 400°C and 600°C of TM doped TiO2 can be designated to the anatase phase (most active phase) without any indication of other crystalline phases such as rutile or brookite . As a variant valence metal cation, Fe, Co ions can react with Ti4+ on the surface of TiO2, and Ti4+ is reduced to Ti3+ which inhibits the transformation of anatase to rutile [1]. It leads to the reduction in the oxygen vacancies on the TiO2 surface and suppresses the crystallization of other phases by adsorbing onto the surface of the TiO2 particles [2]. The photocatalytic degradation of formaldehyde has been successfully demonstrated using a 250 V UV lamp with TM doped TiO2 nano powder in a specific experimental setup. The degradation rate increases linearly with dopant content increases. This indicates that the photocatalytic reaction in this experiment was effected by dopant concentration. The results obtained in this research contribute to the understanding of binary doped transition metal ions in TiO2 nanoparticles can lead the efforts of enhancing their environmental application. Study of Magnatic proprty has been carried out by using VSM. The magnetic susceptibility of the Fe, Co doped TiO2 nanopowder increases with increase in doping concentration. Fe, Co doped TiO2 exhibits ferromagnetism at room temperature. Figure 1

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Verma, Sahil, Sumit Sinha-Ray et Suman Sinha-Ray. « Electrospun CNF Supported Ceramics as Electrochemical Catalysts for Water Splitting and Fuel Cell : A Review ». Polymers 12, n^o 1 (19 janvier 2020) : 238. http://dx.doi.org/10.3390/polym12010238.

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With the per capita growth of energy demand, there is a significant need for alternative and sustainable energy resources. Efficient electrochemical catalysis will play an important role in sustaining that need, and nanomaterials will play a crucial role, owing to their high surface area to volume ratio. Electrospun nanofiber is one of the most promising alternatives for producing such nanostructures. A section of key nano-electrocatalysts comprise of transition metals (TMs) and their derivatives, like oxides, sulfides, phosphides and carbides, etc., as well as their 1D composites with carbonaceous elements, like carbon nanotubes (CNTs) and carbon nanofiber (CNF), to utilize the fruits of TMs’ electronic structure, their inherent catalytic capability and the carbon counterparts’ stability, and electrical conductivity. In this work, we will discuss about such TM derivatives, mostly TM-based ceramics, grown on the CNF substrates via electrospinning. We will discuss about manufacturing methods, and their electrochemical catalysis performances in regards to energy conversion processes, dealing mostly with water splitting, the metal–air battery fuel cell, etc. This review will help to understand the recent evolution, challenges and future scopes related to electrospun transition metal derivative-based CNFs as electrocatalysts.

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Nayak, H. « Kinetic and Thermodynamic Studies on the Non-Isothermal Decomposition of Lanthanum Oxalate Hydrate, Catalysed By Transition Metal Nano Oxides ». IOSR Journal of Applied Chemistry 7, n^o 11 (2014) : 15–23. http://dx.doi.org/10.9790/5736-071121523.

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Shatokha, V., A. Semykina, J. Nakano, S. Sridhar et S. Seetharaman. « A study on transformation of some transition metal oxides in molten steelmaking slag to magnetically susceptible compounds ». Journal of Mining and Metallurgy, Section B : Metallurgy 49, n^o 2 (2013) : 169–74. http://dx.doi.org/10.2298/jmmb120811008s.

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Sustainable development of steelmaking requires solving a number of environmental problems. Economically feasible and environmentally friendly recycling of slag wastes is of special concern. Research of the team representing National Metallurgical Academy of Ukraine, Royal Institute of Technology, Carnegie Mellon University and URS Corp revealed a possibility of the controlled phase transformations in the liquid silicate melts followed by formation of the magnetically susceptible compounds. This approach enables selective recovery of metal values from slag. In this paper, the results obtained and further research directions are discussed. A possibility to exploit physical properties of the transition metals, typical for the metallurgical slags (such as Fe, Mn, V and others), and corresponding specific properties of their compounds, such as non-stoichiometry, mixed valency, pseudomorphosis, thermodynamic stability etc, in production of value-added materials from slag wastes is discussed. The results of the studies of thermodynamics and kinetics of oxidation in slags followed by phase transformation with binary, ternary and complex oxides under various physicochemical conditions are discussed in the view of their application for production of the materials with predefined physical properties. Peculiarities of precipitation in slags with various basicities are analysed and demonstrate capacity of the proposed approach in the production of the material with a given structure and size - for example, nano-sized crystals with structure of spinel. The approaches towards industrial realization of the developed method are also discussed.

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Wainwright, Elliot R., Madeline A. Mueller, Kyle R. Overdeep, Shashank Vummidi Lakshman et Timothy P. Weihs. « Measuring Heat Production from Burning Al/Zr and Al/Mg/Zr Composite Particles in a Custom Micro-Bomb Calorimeter ». Materials 13, n^o 12 (17 juin 2020) : 2745. http://dx.doi.org/10.3390/ma13122745.

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Al:Zr, Al-8Mg:Zr, and Al-38Mg:Zr nanocomposite particles fabricated by physical vapor deposition (PVD) and ball milling were reacted in 1 atm of pure O2 within a custom, highly-sensitive micro-bomb calorimeter. The heats of combustion were compared to examine the effect of particle size and composition on combustion efficiency under room temperature and in a fixed volume. All particles yielded ~60–70% of their theoretical maximum heat of combustion and exhibited an increase in heat over composite thin films of similar compositions, which is attributed to an increase in the surface area to volume ratio. The effect of particle size and geometry are mitigated owing to the sintering of the particles within the crucible, implying the importance of particle dispersion for enhanced performance. Vaporization of the metal species may transition between two diffusion flame species (Mg to Al). As Mg content is increased, more vaporization may occur at lower temperatures, leading to an additional stage of sintering. Physically intermixed Al and Mg oxides have been observed coating the surface of the particles, which implies a continuous transition of these vaporization processes. Such nano-oxides imply high vapor-flame combustion temperatures (>2700 K) and suggest viability for agent defeat applications.

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Zhang, Dan, Lifeng Xie et Bin Li. « Effects of Nano-Nickel Oxide on Thermokinetics, Thermal Safety, and Gas-Generating Characteristics of 5-Aminotetrazole Thermal Degradation ». Fire 6, n^o 4 (21 avril 2023) : 172. http://dx.doi.org/10.3390/fire6040172.

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5-aminotetrazole (5AT) has been widely used as a fuel in SPGGs for its high nitrogen content, heat resistance, and environmentally friendly product. However, 5AT-based propellants still have disadvantages, such as a high exhaust temperature and unstable combustion rate, which somewhat limit their application. Given that transition metal oxides are typically employed in small quantities to enhance the performance of solid propellants, this study selected nickel oxide (NiO) nanoparticles as a catalyst and employed them in conjunction with 5AT via mechanical ball milling to investigate their impact on the pyrolysis behavior of 5AT. It was found that the nanoscale NiO particles can significantly reduce the thermal degradation temperature of 5AT according to TG-DSC tests. The calculation of the energy required to initiate the pyrolysis of 5AT using three kinetic methods, namely Friedman (FR), Flynn–Wall–Ozawa (FWO), and Kissinger–Akahira–Sunose (KAS), indicated that the use of NiO nanoparticles can reduce the energy required by more than 46 kJ mol−1, thereby increasing the likelihood of 5AT pyrolysis. Meanwhile, the reduced thermal safety parameters indicated that NiO makes 5AT more susceptible to thermal decomposition due to thermal explosion transition, so more care is needed for the storage of 5AT. Moreover, the TG-FTIR test was conducted to study the pyrolysis mechanism with or without NiO; the results showed that NiO exerts different catalytic effects on the gas products. The results from this study can offer direction and recommendations for future research on solid propellants.

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