A simple adduct from tin tetraiodide SnI4 and octasulfur S8, SnI4⋅(S8)2 (1), is obtained employing a facile reaction. The combination of Sn4+ ions with d10 electron configuration, acentric SnI4 ...tetrahedra, and lone‐pair effects of S8, makes 1 a phase‐matchable infrared NLO crystal with a moderate second‐harmonic generation (SHG) response and a very high laser‐induced damage threshold (LIDT), which is well confirmed by the DFT calculations.
The adduct SnI4⋅(S8)2, obtained by a solid‐state reaction, shows a moderate nonlinear optical (NLO) intensity and a large laser induced damage threshold (LIDT). Its phase‐matchable character and wide IR transparency make it a very promising IR NLO crystal, comparable to the benchmark system AgGaS2 (AGS).
A big challenge for nonlinear optical (NLO) materials is the application in high power lasers, which needs the simultaneous occurrence of large second harmonic generation (SHG) and high laser induced ...damage threshold (LIDT). Herein we report the preparation of a new Ga2Se3 phase, which shows the SHG intensities of around 2.3 times and the LIDT of around 16.7 times those of AgGaS2 (AGS), respectively. In addition, its IR transparent window ca. 0.59–25 μm is also significantly wider than that of AGS (ca. 0.48–≈11.4 μm). The occurrence of the strong SHG responses and good phase‐matching indicate that the structure of the new Ga2Se3 phase can only be non‐centrosymmetric and have a lower symmetry than the cubic γ‐phase. The observed excellent SHG and phase‐matching properties are consistent with our diffraction experiments and can be well explained by using the orthorhombic models obtained through our high throughput simulations.
A simple but perfect case: A new phase of gallium selenides (δ‐Ga2Se3) has been obtained via solid‐state reactions. δ‐Ga2Se3 is phase‐matchable with large second harmonic generation (SHG) responses, high laser‐induced damage thresholds (LIDTs), and wide transparent range of 0.59–25 μm. These properties are all required for the application of NLO materials with high‐power lasers.
The all-solid-state lithium batteries using solid electrolytes are considered to be the new generation of devices for energy storage, which might be a key solution for power electric and hybrid ...electric vehicles in the future. This review focuses on the crystal structures and electrochemical properties of sulfide solid electrolytes. They are classified to several subgroups according to their chemical compositions, namely thiophosphates, halide thiophosphates, sulfide without phosphorus, and glassy sulfides electrolytes, which might be potential solid electrolytes in lithium batteries and may replace the currently used polymeric electrolytes for LIBs. Through discussion, this review provides an insight into future promising sulfide electrolytes.
•Recent research on metal chalcogenide halides is overviewed.•Metal chalcogenide halides demonstrate rich structures.•Metal chalcogenide halides are promising candidates as solid-state electrolytes ...for batteries.•Metal chalcogenide halides are promising candidates as second-order non-linear optical materials in the infrared region.
Given the collaborative effect between different anions, compounds containing two types of anions can have improved physical performance compared with some aspects of those containing only one type of anion. To date, many such compounds have been investigated. This review focuses on metal chalcogenide halides, namely, M–Q–X (M=metal element; Q=S, Se, Te; X=F, Cl, Br, I) compounds. Although they have similar atomic radii, chalcogen atoms have much smaller electronegativities than those of its neighboring halogen atoms, which results in their different bonding styles. The inclusion of X− into chalcogenides can move their optical band gaps to higher values and their coordination polyhedra can become more distorted, albeit with little density change. These structural effects make metal chalcogenide halides a good choice to fine-tune the structures and physical properties of chalcogenides or halides. Several hundreds of metal chalcogenide halides already have been discovered. They demonstrate rich structures and versatile physical properties, enabling their diverse applications in the fields of solid-state electrolytes, second-order non-linear optics and thermoelectricity. Considering their flourishing development, this paper provides an overview of recent achievements in the structural chemistry and physical properties of metal chalcogenide halides.
In the past several years, many efforts have been made to develop polyanion-type cathode materials for sodium ion batteries by chemists and material scientists. These materials are one of the main ...types of promising cathodes though the studies are still in their infancy. This paper reviews almost all the important advances of polyanion-type cathodes on their syntheses, crystal structures, morphologies, electrochemical performance and Na redox mechanisms. It specifically focuses on their crystal chemistry and electrochemical behaviors. The contents are divided into several categories according to their chemical compositions. After introduction of the synthetic methods, phosphates (ortho-, pyro- and fluoro-), silicates, sulfates, and mixed anions type cathodes are summarized and discussed successively.
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•Recent progress on polyanion-type cathode materials for sodium-ion batteries is overviewed.•Ortho-, pyro- and fluoro-phosphates are the main candidates.•Mixed anions-type cathode materials are receiving increasing attention.
Iron sulfides/oxides/fluorides have been profoundly investigated as electrodes for rechargeable batteries recently in view of their high-theory capacities, low cost, and environmentally benign ...nature. Here, Fe3S4 nanoparticles (NPs) wrapped in reduced graphene oxide (Fe3S4 NPs@rGO) have been obtained using a simple one-pot hydrothermal approach, which is characterized using various techniques. As the anode for Li-ion batteries, Fe3S4 NPs@rGO displays a reversible discharge capacity of 950 mA h/g after 100 cycles at 0.1 A/g, and 720 mA h/g capacity can be achieved after 800 cycles even at 1 A/g. Even at 10 A/g, 462 mA h/g capacity can be maintained. The excellent electrochemical properties for Fe3S4 NPs@rGO can be ascribed to a collaborative effect between Fe3S4 NPs and an rGO matrix, which possess high Li-ion storage ability and excellent conductivity, respectively.
Noble metals (e.g., Ru, Ir and Pt) or their derivatives exhibit very appealing activity toward the hydrogen evolution reaction (HER), but their high price and low reserves impede their wide use. ...Herein, we propose a strategy in which, through the manipulation of crystal and electronic structure, one can convert a common metal to have a Pt-like performance for HER. To achieve this goal, a series of MCo2 (M = Ti, Zr, Hf and Sc) has been synthesized by using a rapid arc-melting method. TiCo2 exhibits comparable HER activity to that of Pt/C, for which it requires only −70 mV (V vs. RHE) to reach 10 mA cm−2 with a Tafel slope of 33 mV decade−1 in 1.0 M KOH. Moreover, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) indicate that the lower adsorption energy (ΔGH*) of H on the Co atom in TiCo2, due to the change in Co electronic state, is another key factor to account for its high HER activity. This case study offers a good illustration of how to transform a non-noble metal so it behaves like a noble metal toward HER and can potentially be applied under other conditions.
In this work, we have systematically investigated the HER activity of the RE
2
Co
17
(RE = Y, Pr, Gd, Tb, Ho and Er) series and revealed that their HER activities are highly correlated with the ...averaged Co-Co bond length of each compound. The HER performance follows the order of Gd
2
Co
17
> Tb
2
Co
17
> Pr
2
Co
17
> Y
2
Co
17
> Ho
2
Co
17
> Er
2
Co
17
. This suggests that the unique feature of rare-earth metals, lanthanide contraction, can effectively alter the interatomic spacing and impact the corresponding HER activity. Additionally, Gd
2
Fe
17
and Gd
2
Ni
17
with different d electron density in the system were synthesized and comparison of their HER efficiencies is also discussed. Gd
2
Ni
17
demonstrates the highest HER efficiency among all samples, and it only requires an overpotential (
η
) of 44 mV to acquire a current density of 10 mA cm
−2
. The theoretical calculation offers a clue that the H adsorption energy (GH
ad
) for H atoms on Ni is lower than that on Co and Fe due to the high electron population in the antibonding state of the Ni atom. This well explains the origin of the synergistic effect for the high electrocatalytic HER of these iron triad intermetallics.
In this work, we have systematically investigated the HER activity of RE
2
Co
17
. We discovered that lanthanide contraction can regulate the HER activity of iron triad intermetallics in alkaline media.
Ferrous sulfide (FeS) particles dispersed in the pores of carbon (FeS/PC) from the polyacrylonitrile carbonization were prepared via a facile one-pot solid-state method, which was extensively ...characterized by XRD, SEM, TEM, Raman spectrum, and XPS techniques. As an anode material for lithium-ion batteries, this FeS/PC composite can achieve a high initial discharge capacity of 1428.8 mAh/g at 0.1 C, and can maintain 624.9 mAh/g capacity after 150 cycles. The porous carbon accommodates the volume change during the cycling, and the special structure of the FeS/PC composite results in its advanced electrochemical performance by enhancing the structure stability.
A europium pyrosilicate, Eu2MgSi2O7 (1), is obtained using a high-temperature solid-state reaction. It crystallizes in the tetragonal noncentrosymmetric space group P4combining macron21m, and its ...structure features a 2D structure built by SiO4 and MgO4 tetrahedra, resulting in interlayer cavities occupied by Eu2+ ions. It has a SHG intensity around 0.7 times that of KTP in the particle size range of 45-75 μm under 2.1 μm radiation, demonstrating a relatively strong effect among the silicates. A typical photoluminescence phenomenon of Eu2+ can be observed at 482 nm. Calculations on the electronic structure and optical properties of 1 are performed. Moreover, to discuss the potential of pyrosilicates and related compounds as NLO crystals, the theoretical analysis on other A2BM2O7 compounds is also addressed.
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