Metal Chalcogenide Materials Research Articles

Defect engineering-driven phase structure design of 2H@1T MoS2 for electrochemical hydrogen evolution reaction

Two-dimensional transition metal chalcogenide materials such as MoS2 have broad application prospects in the field of electrochemical hydrogen evolution reaction (HER) due to their unique electronic structure. Herein, we report a defect engineering strategy for regulating the phase structural components of MoS2. We introduced abundant defects in the MoS2 substrate plane by a facile two-step solvothermal method and induced the surrounding 2H MoS2 lattice to transform into 1T phase. At the same time, hexadecyltrimethylammonium bromide (CTAB), as a common surfactant, was introduced to inhibit the stacking of layered catalysts and increased the proportion of 1T phase by 50%. The existence of high content 1T MoS2 phase possesses excellent catalytic activity with a small Tafel slope of 45.9 mV dec−1 and low overpotential of 182 mV at 10 mA cm−2.

Melting, Crystallization, and Alloying Dynamics in Nanoscale Bismuth Telluride.

It is critical to understand the transformation mechanisms in layered metal chalcogenides to enable controlled synthesis and processing. Here, we develop an alumina encapsulation layer-based in situ transmission electron microscopy (TEM) setup that enables the investigation of melting, crystallization, and alloying of nanoscale bismuth telluride platelets while limiting sublimation in the high-vacuum TEM environment. Heating alumina-encapsulated platelets to 700 °C in situ resulted in melting that initiated at edge planes and proceeded via the movement of a sharp interface. The encapsulated melt was then cooled to induce solidification, with individual nuclei growing to form single crystals with the same basal plane orientation as the original platelet and nonequilibrium crystal shapes imposed by the encapsulation layer. Finally, heating platelets in the presence of antimony caused alloying and lattice strain, along with heterogeneous phase formation. These findings provide new insight into important transformation processes in layered metal chalcogenide materials.

Synthesis and Characterization of the Thin Films NiSe2/Si Heterojunction for Solar Cells

Thin film solar cells are preferable to the researchers and in applications due to the minimum material usage and to the rising of their efficiencies. In particular, thin film solar cells, which are designed based one transition metal chalcogenide materials, paly an essential role in solar energy conversion market. In this paper, transition metals with chalcogenide Nickel selenide termed as (NiSe2/Si) are synthesized. To this end, polycrystalline NiSe2 thin films are deposited through the use of vacuum evaporation technique under vacuum of 2.1x10-5 mbar, which are supplied to different annealing temperatures. The results show that under an annealed temperature of 525 K, the nickel sulfoselenide thin films are polycrystalline with an efficient regularity and best crystalline quality. In addition, the results demonstrate that the intersection argument for the optical properties under investigation provid the direct bandgap, over which the films have inferred on variety (1.55 and 1.75 eV). Overall, the results illustrate that an efficiency of 2.89% can be achieved with 525 K temperature.

Emerging Binary Chalcogenide Light Absorbers: Material Specific Promises and Challenges

In the quest for higher efficiency and lower cost solar energy conversion devices, new light absorber materials are being intensively researched. With their attractive optical and electrical properties, metal chalcogenide materials have emerged as promising candidates for these next-generation light absorbers. In this review, we survey studies on chalcogenide light absorbers having a simple binary composition, namely, Cu2S, SnS, GeSe, WSe2, Sb2S3, and Sb2Se3. Each material has its own unique strengths and weaknesses in terms of cost, abundance, optoelectronic properties, secondary phase formation, anisotropic carrier transport, and defect properties. After critical consideration of the unique properties, we scrutinize recently developed strategies for overcoming the material specific challenges while presenting future perspectives on each material.

Metal chalcogenides: An emerging material for electrocatalysis

The excessive consumption of fossil energy caused an energy crisis and a series of environmental issues. Therefore, it is necessary to develop sustainable and clean energy sources. Electrocatalysts play an important role in the development of various new energy devices; in particular, high-efficiency and low-cost catalysts are essential for the large-scale application of these new devices. Among the many electrocatalysts, metal chalcogenides (sulfides, selenides, and tellurides) as emerging materials own abundant active sites and good electrical conductivity and are widely studied for their excellent electrocatalytic performances. This Perspective reviews the recent applications of metal chalcogenide materials in electrocatalysis, including hydrogen evolution reaction, oxygen evolution reaction, and electrolyzing water and specifically summarizes different optimization strategies and catalytic reaction mechanisms. The several regulation strategies include heteroatom doping, phase engineering, heterostructures, and hybrid materials, which are capable of improving conductivity, increasing active site exposure, and reducing the energy barrier of catalytic reactions to enhanced electrocatalytic performances. In Sec. IV, the existing problems and future challenges are proposed for the improvement of catalytic performance of metal chalcogenide materials, which provide an insight into and valuable guidelines for the future development of high-efficiency and low-cost electrocatalysts for new energy devices.

SnS2/TiO2 Nanocomposites for Hydrogen Production and Photodegradation under Extended Solar Irradiation

Earth–abundant transition metal chalcogenide materials are of great research interest for energy production and environmental remediation, as they exhibit better photocatalytic activity due to their suitable electronic and optical properties. This study focuses on the photocatalytic activity of flower-like SnS2 nanoparticles (composed of nanosheet subunits) embedded in TiO2 synthesized by a facile hydrothermal method. The materials were characterized using different techniques, and their photocatalytic activity was assessed for hydrogen evolution reaction and the degradation of methylene blue. Among the catalysts studied, 10 wt. % of SnS2 loaded TiO2 nanocomposite shows an optimum hydrogen evolution rate of 195.55 µmolg−1, whereas 15 wt. % loading of SnS2 on TiO2 exhibits better performance against the degradation of methylene blue (MB) with the rate constant of 4.415 × 10−4 s−1 under solar simulated irradiation. The improved performance of these materials can be attributed to the effective photo-induced charge transfer and reduced recombination, which make these nanocomposite materials promising candidates for the development of high-performance next-generation photocatalyst materials. Further, scavenging experiments were carried out to confirm the reactive oxygen species (ROS) involved in the photocatalytic degradation. It can be observed that there was a 78% reduction in the rate of degradation when IPA was used as the scavenger, whereas around 95% reduction was attained while N2 was used as the scavenger. Notably, very low degradation (<5%) was attained when the dye alone was directly under solar irradiation. These results further validate that the •OH radical and the superoxide radicals can be acknowledged for the degradation mechanism of MB, and the enhancement of degradation efficiency may be due to the combined effect of in situ dye sensitization during the catalysis and the impregnation of low bandgap materials on TiO2.

Heavy Chalcogenide-Based Ionic Liquids in Syntheses of Metal Chalcogenide Materials near Room Temperature.

This minireview describes two strategically different and unexplored approaches to use ionic liquids (IL) containing weakly solvated and highly reactive chalcogenide anions [E‐SiMe3]− and [E−H]− of the heavy chalcogens (E=S, Se, Te) in materials synthesis near room temperature. The first strategy involves the synthesis of unprecedented trimethylsilyl chalcogenido metalates Cat+[M(E‐SiMe3)n]− (Cat=organic IL cation) of main group and transition metals (M=Ga, In, Sn, Zn, Cu, Ag, Au). These fully characterized homoleptic metalates serve as thermally metastable precursors in low‐temperature syntheses of binary, ternary and even quaternary chalcogenide materials such as CIGS and CZTS relevant for semiconductor and photovoltaics (PV) applications. Furthermore, thermally and protolytically metastable coinage metalates Cat+[M(ESiMe3)2]− (M=Cu, Ag, Au; E=S, Se) are accessible. Finally, the use of precursors BMPyr[E‐SiMe3] (E=Se,Te; BMPyr=1‐butyl‐1‐methylpyrrolidinium) as sources of activated selenium and tellurium in the synthesis of high‐grade thermoelectric nanoparticles Bi2Se3 and Bi2Te3 is shortly highlighted. The second synthesis strategy involves the metalation of ionic liquids Cat[S−H] and Cat[Se−H] by protolytically highly active metal alkyls or amides RnM. This rather general approach towards unknown chalcogenido metalates Catm[Rn‐1M(E)]m (E=S, Se) will be demonstrated in a research paper following this short review head‐to‐tail.

In Situ Characterization of Transformations in Nanoscale Layered Metal Chalcogenide Materials: A Review

AbstractLayered metal chalcogenide materials, such as MoS2 and Bi2Te3, have found important applications as 2D materials in emerging electronic devices. To create nanoscale layered chalcogenide materials with precisely controlled structures and properties, it is critical to understand and control how they evolve and transform under various conditions. This Minireview presents an overview of recent research focused on using in situ characterization to understand the atomic‐scale details of transformations during growth, under exposure to reactive chemical and thermal environments, and on interfacing with other materials. These efforts have used techniques including in situ transmission electron microscopy (TEM), X‐ray spectroscopy, and optical methods to understand nanoscale transformations. These in situ studies have provided a substantially improved understanding of transformation mechanisms in layered chalcogenide materials, which is an important step toward the use of these interesting materials in a variety of electronic and electrochemical devices.

Magic-Sized Stoichiometric II-VI Nanoclusters.

Metal chalcogenide nanomaterials have gained widespread interest in the past two decades for their potential optoelectronic, energy, and catalytic applications. The colloidal growth of various forms of these materials, such as nanowires, platelets, and lamellar assemblies, proceeds through certain thermodynamically stable, ultrasmall (<2nm) intermediates called magic-sized nanoclusters (MSCs). Due to quantum confinement and its resultant intriguing properties, isolation or direct synthesis of MSCs and their structure characterization, which is very much challenging, are current topics of fundamental and applied scientific research. By comprehensive understanding of the structure-activity relationships in MSCs, the nucleation and growth processes can be manipulated, resulting in the synthesis of novel metal chalcogenide materials for various applications. This review focuses on recent advances in the chemical synthesis, characterization, and theoretical calculations of CdSe and its related II-VI nanoclusters. It highlights the studies of photophysical and magneto-optical properties as well as heteroatom doping of MSCs followed by their chemical transformation to high-dimensional nanostructures. At the end of the review, future directions and possible ways to overcome the challenges in the research of semiconductor MSCs are also presented.

Conversion Reaction Mechanism for Yolk‐Shell‐Structured Iron Telluride‐C Nanospheres and Exploration of Their Electrochemical Performance as an Anode Material for Potassium‐Ion Batteries

AbstractVarious metal chalcogenide materials have been investigated as novel candidate anode materials for K‐ion batteries (KIBs). This pioneering study explores the electrochemical reaction between K‐ions and iron telluride. A detailed analysis is performed using in situ and ex situ methods, including X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and cyclic voltammetry (CV), following the initial discharging and charging processes. The reversible reaction mechanism, from the second cycle of the reaction of FeTe2 with K‐ions, is 2Fe + K5Te3 + K2Te ↔ 2FeTe1.1 + 1.8Te + 7K+ + 7e‐. Hollow carbon nanospheres housing iron telluride nanocrystals (FeTe2‐C) are synthesized via facile infiltration and a one‐step tellurization process to compensate for the substantial volume change of nanocrystals during the potassiation and depotassiation processes. Excellent electrochemical properties arise from the synergistic effect of the heterointerfaced FeTe1.1 and metalloid Te formed after one cycle and the yolk‐shell architecture with uniformly distributed nanocrystals are embedded in a carbon shell. FeTe2‐C electrode demonstrates remarkable long‐term cycle performance (171 mA h g‐1 for the 500th cycle at a high current density of 0.5 A g‐1) and an excellent rate capability (126 mA h g‐1), even at a high current density of 10 A g‐1.

Conversion reaction mechanism of cobalt telluride-carbon composite microspheres synthesized by spray pyrolysis process for K-ion storage

Owing to its similarity to lithium and sodium, potassium has been increasingly used to fabricate potassium ion batteries (KIBs). Following vigorous attempts to identify highly efficient electrode materials, transition metal chalcogenide materials have been identified as promising candidates. In this study, the performance of metal telluride (cobalt telluride) as new anode material for KIBs is investigated. Cobalt telluride-C (CoTe2-C) composite microspheres are synthesized using spray pyrolysis. Thereafter, a facile one-step post-treatment process results in the formation of pure-phase CoTe2-C composite microspheres with uniform composition, owing to the direct embedding of Te within the composite microspheres. Conversely, tellurization via application of H2Te gas results in inhomogeneous CoTe2-C composite microspheres, arising from crystal growth of CoTe2, owing to Ostwald ripening. The conversion reaction mechanism of CoTe2-C microspheres for K-ion storage has been examined using in-situ and ex-situ measurements and the reversible reaction mechanism from the second cycle of the reaction of CoTe2 with K ions, described by the reaction: 2Co + K5Te3 + K2Te ↔ 2CoTe + 2Te + 7 K+ + 7e−. Additionally, at a current density of 0.5 A g−1, the discharge capacity of the CoTe2-C composite was 189.5 mA h g−1 for the 100th cycle.

Analyzing and Tuning the Chalcogen-Amine-Thiol Complexes for Tailoring of Chalcogenide Syntheses.

The amine-thiol solvent system has been used extensively to synthesize metal chalcogenide thin films and nanoparticles because of its ability to dissolve various metal and chalcogen precursors. While previous studies of this solvent system have focused on understanding the dissolution of metal precursors, here we provide an in-depth investigation of the dissolution of chalcogens, specifically Se and Te. Analytical techniques, including Raman, X-ray absorption, and NMR spectroscopy and high-resolution tandem mass spectrometry, were used to identify pathways for Se and Te dissolution in butylamine-ethanethiol and ethylenediamine-ethanethiol solutions. Se in monoamine-monothiol solutions was found to form ionic polyselenides free of thiol ligands, while in diamine-monothiol solutions, thiol coordination with polyselenides was predominately observed. When the relative concentration of thiol is increased to that of Se, the chain length of polyselenide species was observed to shorten. Analysis of Te dissolution in diamine-thiol solutions also suggested the formation of relatively unstable thiol-coordinated Te ions. This instability of Te ions was found to be reduced by codissolving Te with Se in diamine-thiol solutions. Analysis of the codissolved solutions revealed the presence of atomic interaction between Se and Te through the identification of Se-Te bonds. This new understanding then provided a new route to dissolve otherwise insoluble Te in butylamine-ethanethiol solutions by taking advantage of the Se2- nucleophile. Finally, the knowledge gained for chalcogen dissolutions in this solvent system allowed for controlled alloying of Se and Te in PbSenTe1-n material and also provided a general knob to alter various metal chalcogenide material syntheses.

Emergence of Topologically Nontrivial Spin-Polarized States in a Segmented Linear Chain.

The synthesis of new materials with novel or useful properties is one of the most important drivers in the fields of condensed matter physics and materials science. Discoveries of this kind are especially significant when they point to promising future basic research and applications. van der Waals bonded materials comprised of lower-dimensional building blocks have been shown to exhibit emergent properties when isolated in an atomically thin form [1-8]. Here, we report the discovery of a transition metal chalcogenide in a heretofore unknown segmented linear chain form, where basic building blocks each consisting of two hafnium atoms and nine tellurium atoms (Hf_{2}Te_{9}) are van der Waals bonded end to end. First-principle calculations based on density functional theory reveal striking crystal-symmetry-related features in the electronic structure of the segmented chain, including giant spin splitting and nontrivial topological phases of selected energy band states. Atomic-resolution scanning transmission electron microscopy reveals single segmented Hf_{2}Te_{9} chains isolated within the hollow cores of carbon nanotubes, with a structure consistent with theoretical predictions. van der Waals bonded segmented linear chain transition metal chalcogenide materials could open up new opportunities in low-dimensional, gate-tunable, magnetic, and topological crystalline systems.

Scalable and Universal Route for the Deposition of Binary, Ternary, and Quaternary Metal Sulfide Materials from Molecular Precursors.

A range of binary, ternary (CFS), and quaternary (CZTS) metal sulfide materials have been successfully deposited onto the glass substrates by air-spray deposition of metal diethyldithiocarbamate molecular precursors followed by pyrolysis (18 examples). The as-deposited materials were characterized by powder X-ray diffraction (p-XRD), Raman spectroscopy, secondary electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy, which in all cases showed that the materials were polycrystalline with the expected elemental stoichiometry. In the case of the higher sulfides, EDX spectroscopy mapping demonstrated the spatial homogeneity of the elemental distributions at the microscale. By using this simple and inexpensive method, we could potentially fabricate thin films of any given main group or transition metal chalcogenide material over large areas, theoretically on substrates with complex topologies.

Direct bilayer growth: a new growth principle for a novel WSe2 homo-junction and bilayer WSe2 growth.

Homo-junction and multi-layer structures of transition metal chalcogenide (TMD) materials provide great flexibility for band-structure engineering and designing photoelectric devices. However, the knowledge of van der Waals epitaxy growth limits the development of these heterostructures. Herein, we employed the chemical vapor deposition (CVD) growth strategy to synthesize novel WSe2 homo-junction samples with a triangular monolayer in the center and three AA stacking bilayer flakes connected to the vertexes of the monolayer. The emitted photon energy from the bilayer near the junction showed a blueshift in energy of up to 24 meV compared with bare bilayer WSe2, confirming the charge transfer effect from monolayer to bilayer WSe2. Further growth studies revealed the shape evolution from WSe2 homo-junction to bilayer. The whole homo-junction formation and evolution process cannot be explained by the traditional layer-by-layer growth mechanism. Instead, a direct bilayer growth approach is proposed to explain the bilayer formation and evolution at the vertexes of the bottom layer of WSe2. These findings suggest that the growth of bilayer TMDs is more complex than our previous understanding. This work presents deepens insight into van der Waals epitaxy growth, and thus is valuable for guiding the fabrication of novel homo-junctions for both fundamental science and optoelectronic applications.

Homoleptic Group 13 Trimethylsilylchalcogenolato Metalates [M(ESiMe3)4]- (M = Ga, In; E = S, Se): Metastable Precursors for Low-Temperature Syntheses of Chalcogenide-Based Materials.

We communicate the synthesis and full characterization of so far unknown tetrakis(trimethylsilylsulfido) and -(trimethylsilylselenido) gallates and indates in form of their organic salts Cat+[M(ESiMe3)4]- (M = Ga, In; E = S, Se; Cat = dimethylpyrrolidinium (DMPyr+), Ph4P+, (dppe)2Cu+, (dmpe)2Cu+). These thermally metastable silylchalcogenolatometalates can act as modular precursors for an ionic-liquid- or organic-solution-based low-temperature synthesis of multinary metal chalcogenide materials such as the CIGS species Cu(InxGa1-x)(SySe1-y)2.

Formation of Horizontally and Vertically Oriented MoS2 and MoSe2 Films Using Cracked Small S- and Se-Molecules and Its Applications for Transparent a-Si:H Thin Film Photovoltaic Devices

Molybdenum dichalcogenide films (MoX2, X=S, Se) were fabricated on 6-inch wafers by a breakthrough technique utilizing cracked small X-molecules. Uniformly deposited Mo-metal films were sulfurized or selenized by reactive chalcogen (Xa, a= 1- 2) small molecules, and MoX2 film was approximately 3 times thicker than the Mo metal precursor. The behavior of reaction chamber pressure according to the cracking temperature indicated that one large molecule could crack into 4 – 5 small particles in experimental condition used in this work. The formation of protrusions was also effectively inhibited to obtain MoX2 films of a device quality. First, I will explain how effectively large chalcogen molecules (normally X8) were cracked, and the cracking effect on the film quality. By controlling the cracking temperature separately, we could lower the growth temperature down to 400 oC or lower. The effect of cracking and X-source evaporation temperatures on the film quality will be also presented. The film quality was dependent on the deposition technique of Mo metal films. The films were characterized using x-ray photoelectron spectroscopy (XPS), Raman scattering, atomic force microscopy (AFM), and transmission electron microscopy (TEM). Cross sectional high resolution TEM image, energy-dispersive x-ray spectroscopy, and angle-resolved XPS analysis of 6 nm-thick MoS2 sulfurized at 570 oC showed that the film has well-aligned layer-by-layer crystalline structure and the composition and chemical states were uniform through depth. Normally, layer-by-layer grown MoX2 films on very flat surfaces are studied for device applications as reported in earlier works. But, practical devices require the growth of semiconductor films on rough and/or patterned surfaces. Then, we studied the formation of a few nm-thick and a few tens nm-thick MoX2 films on rough surfaces, and found that the MoX2 films could be successfully grown on a very rough substrate (root mean square roughness = 38 nm) using the method introduced in this work. When MoX2 films were grown by chalcogenizing Mo, the crystalline orientation of MoX2 films depended on the thickness of Mo films. When the Mo film is thinner than 5 nm, we could obtain layer-by-layer structured, i.e., MoX2 films. We had reported the successful application of the horizontally grown MoX2 film to the field effect transistors in the previous work [1]. Contrarily, when the Mo film was 5 nm or thicker, the formed MoX2 films had vertically oriented crystalline structure. It is because the stress due to 3 times volume expansion should be released by changing the crystalline orientation from planar layer-by-layered to vertically oriented structures. In this work, we utilized the vertically oriented MoX2 films as an interlayer between the semiconductor layer and the electrode. By adopting the MoX2 interlayer in amorphous silicon (a-Si:H) thin film photovoltaic devices having the inverted structure, we could obtain greatly improved cell performances. In the substrate type photovoltaic cells, the shunt resistance increased from 10 kΩ (no MoSe2) to 18 kΩ (with MoSe2) and the open circuit voltage increased from 0.717 V to 0.785 V. The a-Si:H photovoltaic cell having 26 % visible light transmittance on a glass substrate showed the conversion efficiency of 7.7 % under blue light irradiation of 7 mW/cm2. In conclusion, the horizontally and vertically oriented MoX2 films of high crystallinity were formed by chalcogenizing Mo metal films using reactive cracked small X-molecules, and the use of MoX2 film as an interlayer greatly improved the performance of a-Si:H thin film photovoltaic devices. The growth method introduced in this work would be one of the most promising methods to obtain uniform and high quality metal dichalcogenide films on a large substrate. The most important advantage of this method is that it can be easily applied to other metal chalcogenide materials. [1] Jung, K. H.; Yun, S. J.; Choi, Y.; Cho, J. H.; Lim, J. W.; Chai, H.-J.; Cho, D.-H.; Chung, Y.-D.; Kim, G. Nanoscale 2018, 10, 15213-15221.

Electrical and thermal transport properties of S- and Te-doped InSe alloys

Metal chalcogenide materials, including indium selenide (InSe), have attracted attention as potential thermoelectric materials due to their intrinsically low thermal conductivity, which is due to their layered structure with weak atomic bonding. However, their low electrical conductivity should be increased for application as thermoelectric materials. In this study, we examined the electrical and thermal transport properties of 7% S- or Te-doped InSe polycrystalline alloys (InSe0.93S0.07 and InSe0.93Te0.07). These anion substitutions increased the electrical conductivity of InSe, while the enhancement was larger for the Te-doped InSe with a smaller bandgap. The negative Seebeck coefficient did not change significantly upon doping, resulting in enhancement of the power factor. Doping caused a relatively large reduction of thermal conductivity due to additional point defect phonon scattering. Consequently, the thermoelectric figure of merit (zT) increased by 62% and 230% to a maximum of 0.13 and 0.28 at 735 K for InSe0.93S0.07 and InSe0.93Te0.07, respectively, which offers the possibility of InSe-based thermoelectric materials. Cation doping could increase the zT of S/Te-doped InSe further.

Solution-Based Synthesis and Processing of Metal Chalcogenides for Thermoelectric Applications

Metal chalcogenide materials are current mainstream thermoelectric materials with high conversion efficiency. This review provides an overview of the scalable solution-based methods for controllable synthesis of various nanostructured and thin-film metal chalcogenides, as well as their properties for thermoelectric applications. Furthermore, the state-of-art ink-based processing method for fabrication of thermoelectric generators based on metal chalcogenides is briefly introduced. Finally, the perspective on this field with regard to material production and device development is also commented upon.

Recent Advances in Metal Chalcogenides (MX; X = S, Se) Nanostructures for Electrochemical Supercapacitor Applications: A Brief Review.

Supercapacitors (SCs) have received a great deal of attention and play an important role for future self-powered devices, mainly owing to their higher power density. Among all types of electrical energy storage devices, electrochemical supercapacitors are considered to be the most promising because of their superior performance characteristics, including short charging time, high power density, safety, easy fabrication procedures, and long operational life. An SC consists of two foremost components, namely electrode materials, and electrolyte. The selection of appropriate electrode materials with rational nanostructured designs has resulted in improved electrochemical properties for high performance and has reduced the cost of SCs. In this review, we mainly spotlight the non-metallic oxide, especially metal chalcogenides (MX; X = S, Se) based nanostructured electrode materials for electrochemical SCs. Different non-metallic oxide materials are highlighted in various categories, such as transition metal sulfides and selenides materials. Finally, the designing strategy and future improvements on metal chalcogenide materials for the application of electrochemical SCs are also discussed.