Electronic structure of CoSe2 studied by photoemission spectroscopy using synchrotron radiation

Sato, Hitoshi; Nagasaki, F.; Kani, Yukimune; Senba, S.; Ueda, Y.; Kimura, Akio; Takeuchi, Masaki

doi:10.1016/s0038-1098(01)00172-7

Cited by 13 publications

(7 citation statements)

References 21 publications

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“…A few studies have been conducted on the preparation and application of CoX 2 . For example, a nonlayered material CoS 2 is reported as ferromagnetic metal with the Curie temperature T C of 124 K, and CoSe 2 with the pyrite-type structure is regarded as the controversial Pauli paramagnet or the antiferromagnet. − Some initial efforts have also been made on CoTe 2 in two dimensions recently. Duan and co-workers reported the layer-controlled growth of CoTe 2 and CoSe and studied the electric properties of the resulting nanosheets. , Wang and co-workers found tunable magnetic properties of CoTe 2 treated with different concentrations of NaOH .…”

Section: Introductionmentioning

confidence: 99%

Thickness-Controlled Synthesis of CoX₂ (X = S, Se, and Te) Single Crystalline 2D Layers with Linear Magnetoresistance and High Conductivity

et al. 2020

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Two-dimensional (2D) materials especially transition metal dichalcogenides (TMDs) have drawn intensive interest owing to their plentiful properties. Some TMDs with magnetic elements (Fe, Co, Ni, etc.) are reported to be magnetic theoretically and experimentally, which undoubtedly provide a promising platform to design functional devices and study physical mechanisms. Nevertheless, plenty of theoretical TMDs remain unrealized experimentally. In addition, the governable synthesis of these kinds of TMDs with desired thickness and high crystallinity poses a tricky challenge. Here, we report a controlled preparation of CoX2 (X = S, Se, and Te) nanosheets through chemical vapor deposition. The thickness, lateral scale, and shape of the crystals show great dependence on temperature, and the thickness can be controlled from a monolayer to tens of nanometers. Magneto-transport characterization and density function theory simulation indicate that CoSe2 and CoTe2 are metallic. In addition, unsaturated and linear magnetoresistance have been observed even up to 9 T. The conductivity of CoSe2 and CoTe2 can reach 5 × 106 and 1.8 × 106 S/m, respectively, which is pretty high and even comparable with silver. These cobalt-based TMDs show great potential to work as 2D conductors and also provide a promising platform for investigating their magnetic properties.

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Section: Introductionmentioning

confidence: 99%

Thickness-Controlled Synthesis of CoX₂ (X = S, Se, and Te) Single Crystalline 2D Layers with Linear Magnetoresistance and High Conductivity

et al. 2020

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“…As one of the important TMCs for industrial application, cobalt selenide is known as a metallic conductor and an exchange-enhanced Pauli paramagnet in its ground state with a Curie temperature, T c , of 124 K. [26][27][28] Stable phases of cobalt selenide including Co 9 Se 8 , CoSe, Co 0.85 Se and CoSe 2 can be obtained at room temperature. 26,[29][30][31] the fields of energy evolution and storage such as fuel cells, solar cells, and supercapacitors, and even in the catalytic decomposition of toxic pollutants and catalytic hydrogenation of organics.…”

Section: Introductionmentioning

confidence: 99%

Two dimensional layered Co_0.85Se nanosheets as a high-capacity anode for lithium-ion batteries

et al. 2016

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In recent years, two-dimensional (2D) layered transitional metal chalcogenides (TMCs) have received much attention as promising electrode materials in energy storage. Although recent reports on 2D TMC nanostructures have demonstrated promising electrochemical performances, the major scientific challenge is to develop a viable synthesis process to produce layered structures of chalcogenides (Co, Ni or Fe based TMCs) as anode materials. In this work, we propose the synthesis of layered Co0.85Se nanosheets in a solution based method by using a 2D oriented attachment strategy. The as-prepared Co0.85Se nanosheets exhibit specific capacities as high as 675 mA h g(-1) at 100 mA g(-1). When the current densities were further increased to 200, 500 and 1000 mA g(-1), the reversible capacities can still reach up to 645, 574 and 493 mA h g(-1) with excellent cycling life of 95, 85 and 73%, respectively. Li-ion storage performance of layered Co0.85Se nanosheets is higher than that of Co0.85Se microspheres as well as cobalt sulfide. The superior electrochemical performance of Co0.85Se nanosheets is attributed to their 2D layered structure which enhances electrical conductivity and improves diffusion pathways of the Li-ion within the host material. The synthesis method described in this work serves as a general route for the design and preparation of other 2D layered TMCs.

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“…A serious challenge was developing convenient and simple methods to prepare these pyrite materials. Transition metal dichalcogenides have been composited by using the direct stoichiometric combination of component in evacuated tubes . However, as a result of the limit of slow diffusion, the whole response needs to operate at a high temperature from 500 to 1200 °C, and intermittent grinding.…”

Section: Resultsmentioning

confidence: 99%

Influence of selenization temperature on synthesis, morphology, and properties of nanostructured CoSe₂ films

Shi

Kao

et al. 2015

Crystal Research and Technology

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Nanostructured cobalt selenide (CoSe 2 ) thin films were deposited on a glass substrate using the selenization of Co films at different selenization temperatures (300°C, 400°C, and 500°C) in a pure Se vapor for two hours. The morphology and structure of the as-deposited films shows that the film morphology and crystallinity are affected by the selenization temperature. Increasing the selenization temperature from 300°C to 400°C and 500°C results in a change in the surface and cross sectional morphology. At 300°C, the Co films have an almost amorphous structure, while at temperatures of 400 and 500°C, the Co films have a crystalline nanostructure with bilayered morphology. Optical analyses of the CoSe 2 films at 500°C show a large absorption (α > 1.0 × 10 5 cm −1 ) and a direct band gap (ß1.0 eV).

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Electronic structure of CoSe2 studied by photoemission spectroscopy using synchrotron radiation

Cited by 13 publications

References 21 publications

Thickness-Controlled Synthesis of CoX₂ (X = S, Se, and Te) Single Crystalline 2D Layers with Linear Magnetoresistance and High Conductivity

Thickness-Controlled Synthesis of CoX₂ (X = S, Se, and Te) Single Crystalline 2D Layers with Linear Magnetoresistance and High Conductivity

Two dimensional layered Co_0.85Se nanosheets as a high-capacity anode for lithium-ion batteries

Influence of selenization temperature on synthesis, morphology, and properties of nanostructured CoSe₂ films

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Electronic structure of CoSe2 studied by photoemission spectroscopy using synchrotron radiation

Cited by 13 publications

References 21 publications

Thickness-Controlled Synthesis of CoX2 (X = S, Se, and Te) Single Crystalline 2D Layers with Linear Magnetoresistance and High Conductivity

Thickness-Controlled Synthesis of CoX2 (X = S, Se, and Te) Single Crystalline 2D Layers with Linear Magnetoresistance and High Conductivity

Two dimensional layered Co0.85Se nanosheets as a high-capacity anode for lithium-ion batteries

Influence of selenization temperature on synthesis, morphology, and properties of nanostructured CoSe2 films

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Product

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Thickness-Controlled Synthesis of CoX₂ (X = S, Se, and Te) Single Crystalline 2D Layers with Linear Magnetoresistance and High Conductivity

Thickness-Controlled Synthesis of CoX₂ (X = S, Se, and Te) Single Crystalline 2D Layers with Linear Magnetoresistance and High Conductivity

Two dimensional layered Co_0.85Se nanosheets as a high-capacity anode for lithium-ion batteries

Influence of selenization temperature on synthesis, morphology, and properties of nanostructured CoSe₂ films