MoS2 Nanosheets Vertically Grown on Carbonized Corn Stalks as Lithium-Ion Battery Anode

Ex Situ Characterization of 1T/2H MoS2 and Their Carbon Composites for Energy Applications, a Review

The growing interest in the development of next-generation net zero energy systems has led to the expansion of molybdenum disulfide (MoS₂) research in this area. This activity has resulted in a wide range of manufacturing/synthesis methods, controllable morphologies, diverse carbonaceous composite structures, a multitude of applicable characterization techniques, and multiple energy applications for MoS₂. To assess the literature trends, 37,347 MoS₂ research articles from Web of Science were text scanned to classify articles according to energy application research and characterization techniques employed. Within the review, characterization techniques are grouped under the following categories: morphology, crystal structure, composition, and chemistry. The most common characterization techniques identified through text scanning are recommended as the base fingerprint for MoS₂ samples. These include: scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Similarly, XPS and Raman spectroscopy are suggested for 2H or 1T MoS₂ phase confirmation. We provide guidance on the collection and presentation of MoS₂ characterization data. This includes how to effectively combine multiple characterization techniques, considering the sample area probed by each technique and their statistical significance, and the benefit of using reference samples. For ease of access for future experimental comparison, key numeric MoS₂ characterization values are tabulated and major literature discrepancies or currently debated characterization disputes are highlighted.

High-Performance Flexible Energy Storage Devices Based on Graphene Decorated with Flower-Shaped MoS2 Heterostructures

MoS₂, owing to its advantages of having a sheet-like structure, high electrical conductivity, and benign environmental nature, has emerged as a candidate of choice for electrodes of next-generation supercapacitors. Its widespread use is offset, however, by its low energy density and poor durability. In this study, to overcome these limitations, flower-shaped MoS₂/graphene heterostructures have been deployed as electrode materials on flexible substrates. Three-electrode measurements yielded an exceptional capacitance of 853 F g^-1 at 1.0 A g^-1, while device measurements on an asymmetric supercapacitor yielded 208 F g^-1 at 0.5 A g^-1 and long-term cyclic durability. Nearly 86.5% of the electrochemical capacitance was retained after 10,000 cycles at 0.5 A g^-1. Moreover, a remarkable energy density of 65 Wh kg^-1 at a power density of 0.33 kW kg^-1 was obtained. Our MoS₂/Gr heterostructure composites have great potential for the development of advanced energy storage devices.

N-doped graphene encapsulated MoS2nanosphere composite as a high-performance anode for lithium-ion batteries

MoS₂is widely used in lithium-ion batteries (LIBs) due to its high capacity (670 mAh g^-1) and unique two-dimensional structure. However, the further application was limited of MoS₂as anode materials suffer from its volume expansion and low conductivity. In this work, N-doped graphene encapsulated MoS₂nanosphere composite (MoS₂@NG) were prepared and its unique sandwich structure containing abundant mesopores and defects can efficiently enhance reaction kinetics. The MoS₂@NG electrode shows a reversible capacity of 975.9 mAh g^-1at 0.1 A g^-1after 100 cycles, and a reversible capacity of 325.2 mAh g^-1is still maintained after 300 cycles at 5 A g^-1. In addition, the MoS₂@NG electrode exhibites an excellent rate performance benefiting from the electrochemical properties dominated by capacitive behavior. This suggests that MoS₂@NG composite can be used as potential anode materials for LIBs.

Molybdenum disulfide nanosheets: From exfoliation preparation to biosensing and cancer therapy applications

Over the past few decades, nanotechnology has developed rapidly. Various nanomaterials have been gradually applied in different fields. As a kind of two-dimensional (2D) layered nanomaterial with a graphene-like structure, molybdenum disulfide (MoS₂) nanosheets have broad research prospects in the fields of tumor photothermal therapy, biosensors and other biomedical fields because of their unique band gap structure and physical, chemical and optical properties. In this paper, the latest research progress on MoS₂ is briefly summarized. Several commonly used exfoliation methods for the preparation of MoS₂ nanosheets are reviewed based on the studies in the past five years. Additionally, the current research status of MoS₂ nanosheets in the field of biomedicine is introduced. At the end of this review, a brief overview of the limitations of MoS₂ research and its future prospects in the field of biomedicine is also provided.

Construction of hierarchical V4C3-MXene/MoS2/C nanohybrids for high rate lithium-ion batteries

MoS2 is a promising anode candidate for high-performance lithium-ion batteries (LIBs) due to its unique layered structure and high specific capacity. However, the poor conductivity and unsatisfactory structural stability limit its practical application. Recently, a new class of 2D materials, V4C3-Mxene, has been found to combine metallic conductivity, high structural stability and rich surface chemistries. Herein, a facile method has been developed to fabricate V4C3-MXene/MoS2/C nanohybrids. Ultrasmall and few-layered MoS2 nanosheets are uniformly anchored on the surface of V4C3-MXene with a thin carbon-coating layer. The ultrasmall and few-layered MoS2 nanosheets can enlarge the specific areas, reduce the diffusion distance of lithium ions, and accelerate the transfer of charge carriers. As a supporting substrate, V4C3-MXene endows the nanohybrid with high electrical conductivity, strong structural stability, and fast reaction kinetics. Moreover, the carbon-coating layer can further enhance the electrical conductivity and structural stability of the hybrid material. Benefiting from these advantages, the V4C3-MXene/MoS2/C electrode shows an excellent cycling stability with a high reversible capability of 622.6 mA h g-1 at 1 A g-1 after 450 cycles, and a superior rate capability of 500.0 mA h g-1 at 10 A g-1. Thus, the V4C3-MXene/MoS2/C nanohybrid could become a promising anode material for high rate LIBs.

Controllable Design of MoS2 Nanosheets Grown on Nitrogen-Doped Branched TiO2 /C Nanofibers: Toward Enhanced Sodium Storage Performance Induced by Pseudocapacitance Behavior

In this work, expanded MoS₂ nanosheets grown on nitrogen-doped branched TiO₂ /C nanofibers (NBT/C@MoS₂ NFs) are prepared through electrospinning and hydrothermal treatment method as anode materials for sodium-ion batteries (SIBs). The continuous 1D branched TiO₂ /C nanofibers provide a large surface area to grow expanded MoS₂ nanosheets and enhance the electronic conductivity and cycling stability of the electrode. The large surface area and doping of nitrogen can facilitate the transfer of both Na⁺ ions and electrons. With the merits of these unique design and extrinsic pseudocapacitance behavior, the NBT/C@MoS₂ NFs can deliver ultralong cycle stability of 448.2 mA h g^-1 at 200 mA g^-1 after 600 cycles. Even at a high rate of 2000 mA g^-1 , a reversible capacity of 258.3 mA h g^-1 can still be achieved. The kinetic analysis demonstrates that pseudocapacitive contribution is the major factor to achieve excellent rate performance. The rational design and excellent electrochemical performance endow the NBT/C@MoS₂ NFs with potentials as promising anode materials for SIBs.

Vertically aligned MoS2 nanosheets on N-doped carbon nanotubes with NiFe alloy for overall water splitting

Schematic illustration of the formation process and performance of overall water splitting for NiFe-NCNT@MoS₂ samples.

MoS2/carbon composites prepared by ball-milling and pyrolysis for the high-rate and stable anode of lithium ion capacitors

Lithium ion capacitors (LICs), bridging the advantages of batteries and electrochemical capacitors, are regarded as one of the most promising energy storage devices. Nevertheless, it is always limited by the anodes that accompany with low capacity and poor rate performance. Here, we develop a versatile and scalable method including ball-milling and pyrolysis to synthesize exfoliated MoS₂ supported by N-doped carbon matrix derived from chitosan, which is encapsulated by pitch-derived carbon shells (MoS₂/CP). Because the carbon matrix with high nitrogen content can improve the electron conductivity, the robust carbon shells can suppress the volume expansion during cycles, and the sufficient exfoliation of lamellar MoS₂ can reduce the ions transfer paths, the MoS₂/CP electrode delivers high specific capacity (530 mA h g^-1 at 100 mA g^-1), remarkable rate capability (230 mA h g^-1 at 10 A g^-1) and superior cycle performance (73% retention after 250 cycles). Thereby, the LICs, composed of MoS₂/CP as the anode and commercial activated carbon (21 KS) as the cathode, exhibit high power density of 35.81 kW kg^-1 at 19.86 W h kg^-1 and high energy density of 87.74 W h kg^-1 at 0.253 kW kg^-1.

Few-Layer MoS2 Nanosheets Encapsulated in N-Doped Carbon Hollow Spheres as Long-Life Anode Materials for Lithium-Ion Batteries

Two-dimensional molybdenum disulfide (MoS₂ ) has been recognized as a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity, but its rapid capacity decay owing to poor conductivity, structure pulverization, and polysulfide dissolution presents significant challenges in practical applications. Herein, triple-layered hollow spheres in which MoS₂ nanosheets are fully encapsulated between inner carbon and outer nitrogen-doped carbon (NC) were fabricated. Such an architecture provides high conductivity and efficient lithium-ion transfer. Moreover, the NC shell prevents aggregation and exfoliation of MoS₂ nanosheets and thus maintains the integrity of the nanostructure during the charge/discharge process. As anode materials for LIBs, the C@MoS₂ @NC hollow spheres deliver a high reversible capacity (747 mA h g^-1 after 100 cycles at 100 mA g^-1 ) and excellent long-cycle performance (650 mA h g^-1 after 1000 cycles at 1.0 A g^-1 ), which confirm its potential for high-performance LIBs.

Hydrogen Bond between Molybdate and Glucose for the Formation of Carbon-Loaded MoS2 Nanocomposites with High Electrochemical Performance

The effects of glucose on the growth and surface properties of MoS₂ with a nanosheet structure were investigated in detail. In the presence of glucose, the hydrothermal reaction of sodium molybdate and thiourea yields carbon-loaded MoS₂ nanocomposites (C/MoS₂). Compared with bare MoS₂ nanosheets with more than six layers obtained in the absence of glucose and carbon spheres with a diameter of 500 nm prepared from the carbonization of glucose, C/MoS₂ consists of one- or three-layered MoS₂ and carbon spheres with a diameter less than 1 nm to give a large Brunauer-Emmett-Teller surface area (3-20 times larger than the individual materials). The surface characterizations reveal that both MoS₂ and carbon spheres of C/MoS₂ have a negative charge on the surface, suggesting that the previously reported explanation, in which the adsorption of MoS₂ and/or molybdate ions on carbon spheres inhibits the growth and aggregation of MoS₂, is not correct. Based on Fourier transform infrared and ¹H NMR spectra, it is demonstrated that glucose acts as the hydrogen bond donor toward polyoxomolybdate species such as Mo₈O₂₆^4-, Mo₇O₂₄^6-, and MoO₄^2- in the range of pH = 2-12. The intermolecular hydrogen bond not only inhibits the growth of both the (002) plane of MoS₂ and carbon spheres, but also enables the formation of C-O-Mo bonds in the in situ generated C/MoS₂. Compared with bare MoS₂, C/MoS₂ not only show a lower over-potential by 60 mV for the electrocatalytic evolution of hydrogen, but also has a larger mass specific capacitance by three times, due to the larger surface area and the interfacial interaction through the C-O-Mo bonds.

A Facile Synthesis of MoS2/g-C3N4 Composite as an Anode Material with Improved Lithium Storage Capacity

The demand for well-designed nanostructured composites with enhanced electrochemical performance for lithium-ion batteries electrode materials has been emerging. In order to improve the electrochemical performance of MoS2-based anode materials, MoS2 nanosheets integrated with g-C3N4 (MoS2/g-C3N4 composite) was synthesized by a facile heating treatment from the precursors of thiourea and sodium molybdate at 550 °C under N2 gas flow. The structure and composition of MoS2/g-C3N4 were confirmed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis and elemental analysis. The lithium storage capability of the MoS2/g-C3N4 composite was evaluated, indicating high capacity and stable cycling performance at 1 C (A·g-1) with a reversible capacity of 1204 mA·h·g-1 for 200 cycles. This result is believed the role of g-C3N4 as a supporting material to accommodate the volume change and improve charge transport for nanostructured MoS2. Additionally, the contribution of the pseudocapacitive effect was also calculated to further clarify the enhancement in Li-ion storage performance of the composite.

Hierarchical Nanospheres Constructed by Ultrathin MoS2 Nanosheets Braced on Nitrogen-Doped Carbon Polyhedra for Efficient Lithium and Sodium Storage

MoS₂ has attracted a lot of attention for electrochemical energy storage. Herein, we design and fabricate unusual hierarchical composite nanospheres by cultivating a MoS₂ sheet-like nanostructure on nitrogen-doped carbon polyhedra (designated as CP@MoS₂ nanospheres). The nitrogen-doped carbon polyhedra are able to significantly boost the electrical conductivity of the hybrid architecture and largely mitigate the agglomeration of the MoS₂ nanostructure. The sheet-like MoS₂ nanostructure can render a great deal of storage sites toward lithium and sodium. When measured as a negative electrode for Li storage, these CP@MoS₂ nanospheres manifest a large charge capacity of approximately 549 mAh g^-1, a superior cycle life of 900 cycles, and excellent rate property. Furthermore, they also demonstrate improved electrochemical activity for Na⁺ ion storage.

Tailored Ni2P nanoparticles supported on N-doped carbon as a superior anode material for Li-ion batteries

The Ni₂P/NPC composite effectively buffers volume expansion and improves electrochemical performances by creating more defects on the surface, indicating overwhelming superiority in energy storage applications.

Chitosan-Induced Synthesis of Hierarchical Flower Ridge-like MoS2/N-Doped Carbon Composites with Enhanced Lithium Storage

Continuous hierarchical MoS₂/C micro/nanostructured composite with strong structural stability and efficient lithium ion and electron transport channels is an urgent need for its successful application in lithium ion battery anode materials. In this study, continuous hierarchical flower ridge-like MoS₂/N-doped carbon micro/nanocomposite (MoS₂/NC) was first synthesized through a simple chitosan-induced one-pot hydrothermal and postsintering method. The amino-containing chitosan is demonstrated to be important not only in nitrogen-doped carbon source, soft template, and surfactant but also in controlling the interlayer distance between adjacent MoS₂ layers. The detailed hierarchical structure, phase characteristics, the number of MoS₂ stacked layers, and interlayer distance were characterized using a scanning electron microscope, transmission electron microscope, X-ray diffraction, and so forth. It reveals that the interconnected nanoflowers composed of few-layer MoS₂ (≤3 layers) nanoflakes with an expanded interlayer distance vertically grow on two-dimensional N-doped carbon nanosheets in the MoS₂/NC composite. When examined as anode of lithium ion batteries, this unique hierarchical MoS₂/NC micro/nanostructure shows better electrochemical performance. The electrode delivers a reversible capacity of 904.7 mA h g^-1 at 200 mA g^-1 after 100 cycles, outstanding cycle stability at high rates (742, 686, 534 mA h g^-1 at 500, 1000, 2000 mA g^-1 after 400 cycles, respectively) and superior rate performance. The above synthesis strategy is a good choice for constructing other hierarchical transition-metal disulfides or oxides and carbon micro/nanostructures to improve their electrochemical performance.

Rationally designed hierarchical porous CNFs/Co3O4 nanofiber-based anode for realizing high lithium ion storage

To achieve a high power density of lithium-ion batteries, it is essential to develop anode materials with high capacity and excellent stability. Cobalt oxide (Co₃O₄) is a prospective anode material on account of its high energy density. However, the poor electrical conductivity and volumetric changes of the active material induce a dramatic decrease in capacity during cycling. Herein, a hierarchical porous hybrid nanofiber of ZIF-derived Co₃O₄ and continuous carbon nanofibers (CNFs) is rationally constructed and utilized as an anode material for lithium-ion batteries. The PAN/ZIF-67 heterostructure composite nanofibers were first synthesized using electrospinning technology followed by the in situ growth method, and then the CNFs/Co₃O₄ nanofibers were obtained by subsequent multi-step thermal treatment. The continuous porous conductive carbon backbone not only effectively provides a channel to expedite lithium ion diffusion and electrode transfer, but also accommodates volume change of Co₃O₄ during the charge–discharge cycling process. The electrode exhibits a high discharge capacity of 1352 mA h g⁻¹ after 500 cycles at a constant current density of 0.2 A g⁻¹. Additionally, the composites deliver a discharge capacity of 661 mA h g⁻¹ with a small capacity decay of 0.078% per cycle at a high current density of 2 A g⁻¹ after 500 cycles. This hierarchical porous structural design presents an effective strategy to develop a hybrid nanofiber for improving lithium ion storage.

Hierarchical porous CNFs/Co₃O₄ nanofiber is rationally designed and constructed as an anode for achieving high capacity and stable lithium ion batteries.