Chemical Intercalations in Layered Transition Metal Chalcogenides: Syntheses, Structures, and Related Properties
TL;DR: In this paper, the authors introduce and summarize the latest advances in chemical intercalation and the role of these spacing layers in transition metal chalcogenides, and their relation to relevant properties.
Abstract: Transition metal chalcogenides (TMChs) have recently attracted a great deal of interest in the chemical and physical research fields. These compounds have a common crystal structure: they usually consist of two-dimensional or quasi-two-dimensional layers stacked along the direction perpendicular to the layers. The combination between layers is generally by van der Waals interaction or weak chemical bonding, making the layered chalcogenides potential hosts for intercalation. Alkali metals, alkaline earths, rare earths, and organic groups or compounds can be intercalated into the structure as spacing layers, resulting in a variety of new compounds and exhibiting interesting physical and chemical properties. In this review, we introduce and summarize the latest advances in chemical intercalation and the role of these spacing layers in TMChs, and their relation to relevant properties. Especially, we focus on the developments of chemical intercalation in Fe chalcogenide superconductors to understand the effect...
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TL;DR: The metastable 1T′ polymorph of molybdenum disulfide (MoS2) has shown excellent catalytic activity toward the hydrogen evolution reaction (HER) in water splitting applications as discussed by the authors.
Abstract: The metastable 1T′ polymorph of molybdenum disulfide (MoS2) has shown excellent catalytic activity toward the hydrogen evolution reaction (HER) in water‐splitting applications. Its basal plane exhi ...
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TL;DR: In this article, a 2D SnS2 nanorods-like morphology with high purity and crystallinity of the sample was synthesized through a controlled strategy and tested as an active electrode material for hybrid supercapacitors.
Abstract: Two dimensional (2D) microstructure materials have attracted considerable attention due to their short-diffusion path length and large interfacial areas for hybrid supercapacitors (HSCs) in recent years. In the typical layered metal chalcogenides family, tin sulfide (SnS2) is one of the important binary compounds explored for energy storage applications. A reasonable construction of a 2D microstructure for HSCs is proposed. The structural study revealed the nanorods-like morphology with high purity and crystallinity of the sample. The 2D SnS2 nanorods were synthesized through a controlled strategy and tested as an active electrode material for HSCs. The electrochemical properties of SnS2 nanorods were examined through different experimental measurements, including both two- and three-electrode systems. In a three-electrode system, the as-synthesized 2D SnS2 nanorods exhibit superior electrochemical properties with a specific capacitance of (270 F g−1 at 10 mVs−1, and 162.2 F g−1 at 3 A g−1) and excellent cycling stability (9% capacitance loss after 8000 repeated CV cycles), due to efficient ion transport between the electrolyte to the active electrode, and charge transport between electrode and current collector, respectively. More importantly, aqueous HSCs were assembled using 2D SnS2//rGO as positive and negative electrodes operating in a wide and stable potential window up to 1.6 V in 1 M NaOH electrolyte. Moreover, HSCs deliver a high specific capacitance of (108 F g−1 at 5 mVs−1, and 92.4 F g−1 at 1 A g−1), a high specific energy of 32.8 Wh kg−1 along with excellent electrochemical stability (93% retention after 4000 cycles) due to the morphology assisted activity and unique structure of the electrode material. Additionally, we demonstrated the single HSC cell which provided sufficient energy to turn on a red LED of 20 mW and emit light over a certain period of time opens up possible realistic applications. The results manifest that the proposed hydrothermal assisted synthesis has promising applications in producing high-performance energy storage devices.
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TL;DR: In this paper, two dimensional hexagonal tin selenide nanosheets have been synthesized using a one-pot colloidal method and tested as active electrode for supercapacitors without using any binder.
Abstract: In the class typical layered metal chalcogenide family, tin selenide (SnSe) has been explored resolutely as one of the significant binary IV-VI compounds for a wide range of energy storage applications. Two dimensional hexagonal tin selenide nanosheets have been synthesized using a one-pot colloidal method and tested as active electrode for supercapacitors without using any binder. The as-prepared SnSe electrode exhibits a capacitance of 617.9 F/g at a scan rate of 2 mV/s with a good electrochemical stability due to efficient ion transport between electrolyte to active electrode and charge transport between electrode and current collector. The high energy density of 28.5 Wh/kg along with high cyclic stability is due to the morphology assisted electrochemical activity of the electrode. The results indicate that the assembly of binder-free electrode by the proposed facile synthesis route has a promising application in producing high-performance energy storage devices.
34 citations
Cites background from "Chemical Intercalations in Layered ..."
...to their distinct geometric structures enabled by weak interlayer Van der Waals link, enriched phase structure and easy re-stacking ability [1], [2]....
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TL;DR: In this article, a hybrid of Cu2MoS4 nanoparticles embedded on reduced graphene oxide (rGO) sheets was prepared via a one-pot hydrothermal method without any surfactants or templates.
Abstract: A novel hybrid of Cu2MoS4 nanoparticles embedded on reduced graphene oxide (rGO) sheets was prepared via a one-pot hydrothermal method without any surfactants or templates. The electrochemical properties of the as-prepared Cu2MoS4–rGO electrode were investigated as an advanced electrode for supercapacitor applications, and it exhibited higher specific capacitance (231.51 F g−1 at 5 mV s−1) compared to the pristine Cu2MoS4 electrode (135.78 F g−1 at 5 mV s−1). The Cu2MoS4–rGO electrode showed energy density of 31.92 Wh kg−1 at a constant current of 1.5 mA, which was higher than that of the pristine Cu2MoS4 electrode (17.91 Wh kg−1 at a constant current of 1.5 mA). The satisfactory enhancement in the electrochemical performance of Cu2MoS4–rGO electrodes could be attributed to the chemical interaction between rGO sheets and Cu2MoS4 nanoparticles, which produced more active sites for the charging/discharging process and enabled fast electron transport through the graphene layers. Furthermore, this work presented an extensive study about the effect of temperature (from 25 °C to 80 °C) on the Cu2MoS4–rGO electrode in an aqueous Na2SO4 electrolyte. The effect of temperature on the electrochemical properties of the Cu2MoS4–rGO electrode was investigated using cyclic voltammetry (CV), charge–discharge (CD) tests and electrochemical impedance spectroscopy (EIS). The electrochemical performance of the Cu2MoS4–rGO electrode exhibited ∼128% improvement at 80 °C compared to that at 25 °C in CD profiles. These experimental results indicate a fundamental comprehension of the temperature-dependent supercapacitor electrodes for industrial, military and space applications.
27 citations
TL;DR: In this article, the negative anode for Na-ion batteries is investigated to meet the requirement for the anodes with high energy density and long life-time, and the electrochemical reaction mechanisms for the transition metal compounds makes it promising negative anodes for NIBs and provides feasible strategy for low cost and large-scale energy storage system in the near future.
Abstract: Rechargeable lithium-ion batteries (LIBs) have been rapidly expanding from IT based applications to uses in electric vehicles (EVs), smart grids, and energy storage systems (ESSs), all of which require low cost, high energy density and high power density. The increasing demand for LIBs has resulted in increasing price of the lithium source, which is a major obstacle to wider application. To date, the possible depletion of lithium resources has become relevant, giving rise to the interest in Na-ion batteries (NIBs) as promising alternatives to LIBs. A lot of transition metal compounds based on conversion-alloying reaction have been extensively investigated to meet the requirement for the anodes with high energy density and long life-time. In-depth understanding the electrochemical reaction mechanisms for the transition metal compounds makes it promising negative anode for NIBs and provides feasible strategy for low cost and large-scale energy storage system in the near future.
23 citations
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TL;DR: It is reported that a layered iron-based compound LaOFeAs undergoes superconducting transition under doping with F- ions at the O2- site and exhibits a trapezoid shape dependence on the F- content.
Abstract: We report that a layered iron-based compound LaOFeAs undergoes superconducting transition under doping with F- ions at the O2- site. The transition temperature (Tc) exhibits a trapezoid shape dependence on the F- content, with the highest Tc of ∼26 K at ∼11 atom %.
6,643 citations
TL;DR: The observation of superconductivity with zero-resistance transition temperature at 8 K in the PbO-type α-FeSe compound is reported, indicating that this compound has the same, perhaps simpler, planar crystal sublattice as the layered oxypnictides.
Abstract: The recent discovery of superconductivity with relatively high transition temperature (Tc) in the layered iron-based quaternary oxypnictides La[O1−xFx] FeAs by Kamihara et al. [Kamihara Y, Watanabe T, Hirano M, Hosono H (2008) Iron-based layered superconductor La[O1-xFx] FeAs (x = 0.05–0.12) with Tc = 26 K. J Am Chem Soc 130:3296–3297.] was a real surprise and has generated tremendous interest. Although superconductivity exists in alloy that contains the element Fe, LaOMPn (with M = Fe, Ni; and Pn = P and As) is the first system where Fe plays the key role to the occurrence of superconductivity. LaOMPn has a layered crystal structure with an Fe-based plane. It is quite natural to search whether there exists other Fe based planar compounds that exhibit superconductivity. Here, we report the observation of superconductivity with zero-resistance transition temperature at 8 K in the PbO-type α-FeSe compound. A key observation is that the clean superconducting phase exists only in those samples prepared with intentional Se deficiency. FeSe, compared with LaOFeAs, is less toxic and much easier to handle. What is truly striking is that this compound has the same, perhaps simpler, planar crystal sublattice as the layered oxypnictides. Therefore, this result provides an opportunity to better understand the underlying mechanism of superconductivity in this class of unconventional superconductors.
2,544 citations
TL;DR: There is a marked resemblance in superconducting properties between the present material and high-Tc copper oxides, suggesting that the two systems have similar underlying physics.
Abstract: Since the discovery of high-transition-temperature (high-T(c)) superconductivity in layered copper oxides, many researchers have searched for similar behaviour in other layered metal oxides involving 3d-transition metals, such as cobalt and nickel. Such attempts have so far failed, with the result that the copper oxide layer is thought to be essential for superconductivity. Here we report that Na(x)CoO2*yH2O (x approximately 0.35, y approximately 1.3) is a superconductor with a T(c) of about 5 K. This compound consists of two-dimensional CoO2 layers separated by a thick insulating layer of Na+ ions and H2O molecules. There is a marked resemblance in superconducting properties between the present material and high-T(c) copper oxides, suggesting that the two systems have similar underlying physics.
1,495 citations
TL;DR: This review describes the recent advances in designing high-performance bulk thermoelectric materials and highlights the decoupling of the electron and phonon transport through coherent interface, matrix/precipitate electronic bands alignment, and compositionally alloyed nanostructures.
Abstract: There has been a renaissance of interest in exploring highly efficient thermoelectric materials as a possible route to address the worldwide energy generation, utilization, and management. This review describes the recent advances in designing high-performance bulk thermoelectric materials. We begin with the fundamental stratagem of achieving the greatest thermoelectric figure of merit ZT of a given material by carrier concentration engineering, including Fermi level regulation and optimum carrier density stabilization. We proceed to discuss ways of maximizing ZT at a constant doping level, such as increase of band degeneracy (crystal structure symmetry, band convergence), enhancement of band effective mass (resonant levels, band flattening), improvement of carrier mobility (modulation doping, texturing), and decrease of lattice thermal conductivity (synergistic alloying, second-phase nanostructuring, mesostructuring, and all-length-scale hierarchical architectures). We then highlight the decoupling of th...
1,469 citations
TL;DR: The response of the worldwide scientific community to the discovery in 2008 of superconductivity at T c'='26'K in the Fe-based compound LaFeAsO1−x F x has been very enthusiastic.
Abstract: The response of the worldwide scientific community to the discovery in 2008 of superconductivity at T c = 26 K in the Fe-based compound LaFeAsO1−x F x has been very enthusiastic. In short order, ot...
1,373 citations