MoS2 Nanospheres Research Articles

Enhanced Fe(Ⅲ)/PMS system by flower-like MoS2 nanosheet for rapid degradation of tetracycline

Despite the achievement of the MoS2/Fe(Ⅱ)/PMS system in the degradation of organic pollutants, the low stability of Fe(Ⅱ) and the poor catalytic effect of bulk MoS2 limit its practical application. Herein, multilayer flower-like MoS2 nanospheres with abundant active sites were successfully prepared by hydrothermal synthesis. It was used as a co-catalyst for the Fe(Ⅲ)/PMS system to stably reduce Fe(Ⅲ) to Fe(Ⅱ) and effectively activate PMS in a wide pH range (3.0–9.0) for tetracycline (TC) removal. The mechanism study showed that the redox cycling of Mo(Ⅳ)/Mo(Ⅵ) and iron with different valences promoted the formation of reactive oxygen species (SO4•-, •OH, FeⅣ = O, O2•-, and 1O2) in MoS2/Fe(Ⅲ)/PMS system, but 1O2 was the main active oxidants. Possible degradation pathways of TC were proposed, and the toxicity of by-products was predicted by toxicity evaluation. The degradation was inhibited by bicarbonate (HCO3-) and dihydrogen phosphate (H2PO4-). MoS2 showed good stability and reactivity for the degradation of TC after five consecutive cycles of experiments. In conclusion, the multilayer flower-like MoS2 nanosphere is a promising catalyst that can be used in advanced oxidation technology.

Characterizations of MoS2 nanosphere fabricated using vacuum thermal evaporation at steady and rapid heating

Two-dimensional MoS2 has been speculated to be the best material to replace graphene due to its peculiar structural-electronic properties. The MoS2 with size smaller than its exciton Bohr radius (ca. 1.61 nm) would favor multi exciton generation upon absorption of photon with sufficient energy, Ephoton ≫ Egap (1.89 eV); which would increase the efficiency of an excitonic solar cell greater than 60%. Despite promising properties of the MoS2, however an excitonic solar cell with high efficiency is yet to be exhibited. In this work, the MoS2 thin films were fabricated using vacuum thermal evaporation technique and characterized. Four objectives have been outlined i.e., to study the effect of heating rate (steady, and rapid) on the (i) morphology, (ii) size, (iii) optoelectronic and (iv) crystal properties of the fabricated thin films. The MoS2 precursor was heated at the rate 2.027 A/s (steady), and 18.75 A/s (rapid), 1.5 × 10−3 Torr, 1.48 A, and 4.58 V. The deposited films later were characterized using Field Emission Scanning Electron Microscope with Energy Dispersive X-ray attachment, photoluminescence spectrometer, UV–vis-NIR spectrometer, and X-ray Diffractometer. The fabricated thin films exhibited nanosphere morphology with different size distributions i.e., wide (steady heating), and narrow (rapid heating). Two hypotheses were made based on the optoelectronic properties i.e., the basic building block of the MoS2 thin film fabricated under steady heating is (i) experiencing stronger quantum confinement effect, and (ii) dominated by nanocrystals which are smaller than that of the rapid heating. Similar energy loss could be expected in both MoS2 thin films i.e., ca. 0.15 to 0.17 eV, indicating the existence of shallow trap states. The MoS2 thin films were dominated by (002), (004), and (106) crystal planes. Therefore, the vacuum thermal evaporation technique would offer materials with unique size, crystal arrangement, and optoelectronic properties upon change of heating rate.

Hollow nanospheres constructed by ultrafine few-layered MoS2 partially with amorphous fragments homogeneously incorporated in N-doped amorphous carbon for enhanced lithium storage performance

The rational design of ultrathin and few-layered structures for three-dimensional MoS2 nanospheres is crucial for achieving attractive lithium-ion batteries (LIBs). Herein, hollow nanospheres constructed by ultrafine and few-layered MoS2 homogeneously incorporated in N-doped amorphous carbon (HUF-MoS2/NC) have been successfully synthesized as high-performance anode for LIBs. Using Mo-glycerol spheres as templates and dopamine hydrochloride as coordination ligands, hollow Mo-glycerol-polydopamine precursors are formed with Mo-containing groups which are surrounded by organic carbon species. Consequently, the MoS2 is confined to the nanoscale and grows partially amorphous fragments while being uniformly embedded in NC. This unique architecture can not only hinder the substantial restacking between MoS2 interlayers, offering more active sites, but also vastly enhance the electrical conductivity and relieve the mechanical stress ascribed to volume changes. As a result, the HUF-MoS2/NC composite anode exhibits excellent cyclic stability (980mAhg−1 after 300 cycles at 0.2Ag−1) and superior rate performance (498mAhg−1 at 5.0Ag−1) for LIBs.

Room-temperature nitrogen dioxide gas sensor based on graphene oxide nanoribbons decorated with MoS2 nanospheres

Room-temperature nitrogen dioxide gas sensor based on graphene oxide nanoribbons decorated with MoS2 nanospheres

Control of the morphologies of molybdenum disulfide for hydrogen evolution reaction

In this study, different morphologies of molybdenum disulfide (MoS2), including MoS2 nanoparticle (NP), MoS2 nanoflower (NF), MoS2 nanosphere (NS), MoS2 nanohollow (NH), and MoS2/MoO2 composite, are successfully synthesized via a facile-route hydrothermal process employing different solutions. The structure and chemical bonding of the different morphologies of MoS2 are investigated via X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Thereafter, the synthesized materials are applied to the hydrogen evolution reaction (HER) employing a three-electrode system in a standard acidic medium (0.5 M H2SO4). The MoS2 NH exhibits higher performance: an overpotential of −230 mV at −10 mAcm−2, a Tafel slope of 64 mVdec−1, a high double-layer capacitance (Cdl) of 11.98 mFcm−2 and larger BET surface area (22.59 m2/g), as well as super stability after stability tests, representing the best catalytic behavior among the synthesized materials. The results indicate that the electrocatalytic efficiencies of materials depend on their morphologies which is highly related to the surface area of catalysts. The results avail a novel avenue for synthesizing the various morphologies of MoS2, as well as the new morphology of MoS2 (MoS2 NH). It can be a promising material for electrocatalytic and energy-storage applications.

N-doped graphene encapsulated MoS2 nanosphere composite as a high-performance anode for lithium-ion batteries

MoS2 is 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 MoS2 as anode materials suffer from its volume expansion and low conductivity. In this work, N-doped graphene encapsulated MoS2 nanosphere 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−1 at 0.1 A g−1 after 100 cycles, and a reversible capacity of 325.2 mAh g−1 is 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

Construction of novel MoS2@COF-Ph heterojunction photocatalysts for boosted photocatalytic efficiency and hydrogen production performance under sunlight

We assemble COF-Ph on MoS2 nanospheres to form a unique interface for high-efficiency photocatalytic degradation of tetracycline, producing hydrogen under sunlight. The Z-scheme heterojunction mechanism promoted the separation of photocarriers to greatly improve performance.

Robust wrinkled MoS2/N-C bifunctional electrocatalysts interfaced with single Fe atoms for wearable zinc-air batteries

The ability to create highly efficient and stable bifunctional electrocatalysts, capable of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in the same electrolyte, represents an important endeavor toward high-performance zinc-air batteries (ZABs). Herein, we report a facile strategy for crafting wrinkled MoS2/N-doped carbon core/shell nanospheres interfaced with single Fe atoms (denoted MoS2@Fe-N-C) as superior ORR/OER bifunctional electrocatalysts for robust wearable ZABs with a high capacity and outstanding cycling stability. Specifically, the highly crumpled MoS2 nanosphere core is wrapped with a layer of single-Fe-atom-impregnated, N-doped carbon shell (i.e., Fe-N-C shell with well-dispersed FeN4 sites). Intriguingly, MoS2@Fe-N-C nanospheres manifest an ORR half-wave potential of 0.84 V and an OER overpotential of 360 mV at 10 mA⋅cm-2 More importantly, density functional theory calculations reveal the lowered energy barriers for both ORR and OER, accounting for marked enhanced catalytic performance of MoS2@Fe-N-C nanospheres. Remarkably, wearable ZABs assembled by capitalizing on MoS2@Fe-N-C nanospheres as an air electrode with an ultralow area loading (i.e., 0.25 mg⋅cm-2) display excellent stability against deformation, high special capacity (i.e., 442 mAh⋅g-1Zn), excellent power density (i.e., 78 mW⋅cm-2) and attractive cycling stability (e.g., 50 cycles at current density of 5 mA⋅cm-2). This study provides a platform to rationally design single-atom-interfaced core/shell bifunctional electrocatalysts for efficient metal-air batteries.

Branched alkylated polynorbornene and 3D flower-like MoS2 nanospheres reinforced phase change composites with high thermal energy storage capacity and photothermal conversion efficiency

Form-stable phase change materials (FSPCMs) have a great attraction for relieving the contradiction of energy consumption and environmental pollution. However, the practical effects of FSPCMs are severely compromised by their intrinsic drawbacks including liquid leakage, inferior cycling durability and lacking light to heat conversion ability, etc. In this paper, we have constructed a group of novel composite FSPCMs with high latent heat storage density, enhanced thermal stability and excellent cycling life, using 1-octadecanol (OCC) as the latent heat storage units and the branched alkylated polynorbornene as well as 3D flower-like MoS2 nanospheres as the supporting scaffolds for the composite FSPCMs. The branched alkylated polynorbornene enhances the toughness of the composites under the induced dipole force among their alkyl chains so that the liquid leakage during the phase transition can be minimized or completely circumvented. Furthermore, 3D flower-like MoS2 nanospheres, as a photothermic absorbent, impart the composite FSPCMs with enhanced light to thermal conversion efficiency (85.5%), promising for a potential application in conversion and storage of solar energy.

One-pot synthesis of MoS2 nanoflowers for thermal energy storage applications

In this study, flower-like MoS2 nanospheres were synthesized via a facile hydrothermal route. The morphological and phase analysis confirmed the formation of polycrystalline MoS2 nanoflowers assembled by lamellar nanosheets. A novel shape-stabilized phase change material was fabricated by imprisoning different concentrations of MoS2 into myristic acid. It was observed from the experimental results that the duration of melting and cooling rates for PCM of 0.25 wt%, 0.5 wt%, 0.75 wt%, 1 wt%, 1.25 wt% increased as compared to pristine counterparts. 1 wt% had the highest heat transfer rate, with a value of 9.4% and 52.81% for melting and cooling, respectively. The result from analytical technique showed there was no chemical reaction between MoS2 and myristic acid even after multiple cycles. Since this unique MoS2 based composite has indicated good thermal reliability for latent-heat storage, and release, this composite can be considered as an appropriate PCM for thermal energy storage applications.

Amphiphilic Janus 3D MoS2/rGO Nanocomposite for Removing Oil from Wastewater

The efficient removal of the fine oil droplets from a large amount of water produced by oil and gas production is a challenge faced by industries not only for environmental concerns but also for cost reduction. Although much effort has been made on developing various separation technologies, we still lack an adequate method to achieve desirable results. The nanoengineered advanced materials could play an important role in achieving the needed breakthrough on the effective removal of fine oil droplets from industrial wastewater. Herein, we report an amphiphilic Janus porous nanocomposite, which consists of oleophilic MoS2 nanospheres that are embedded within the hydrophilic three-dimensional (3D) reduced graphene oxide framework. The Janus MoS2/rGO nanocomposite is synthesized via the hydrothermal process. Our experiments confirmed that this Janus nanocomposite demonstrated 98.56% removal of fine oil droplets from water within 3 min, with remarkable regeneration and recycling ability. This excellent performance is attributed primarily to its Janus structure that offers amphiphilic surface property and high surface activity to effectively enhance the adsorption of oil droplets in the oil and water emulsion environment. These findings hold promise for the next-generation Janus nanocomposite-based technology aiming removal of fine oil droplets from oil- and gas-produced water in the energy industry.

Ultrasonic‐triggered Surface Morphological Reconstruction of MoS2 for Enhanced Ultrasensitive Humidity Sensing

AbstractDefects on a surface can improve response activities in a humidity sensor. A novel preparation process of sonication‐triggered morphological evolution of additional defect was reported in this work. Herein, an ultra‐responsive humidity sensor prepared by defect‐rich MoS2 nanospheres has been demonstrated. The morphology, element distribution and the abundant defects of MoS2 NSs were characterized by SEM, TEM, EDS, XRD, Raman and XPS. There are many defects which act as active adsorption sites on the surface of MoS2 NSs. Profiting by surface defects and fast charge transfer, the defect‐rich MoS2 NSs delivered remarkably ultrasensitive humidity sensing with a response as high as 5560 and ultrafast response‐recovery behaviors, and excellent repeatability. Moreover, the humidity sensing mechanism of the sensor was discussed summarily.

TiO2 NANOPARTICLES DECORATED FLOWER-LIKE MoS2 NANOSPHERES WITH ENLARGED INTERLAYER SPACING OF (002) PLANE FOR ENHANCED TRIBOLOGICAL PROPERTIES

In this work, TiO2@MoS2 heterojunction of TiO2 nanoparticles decorated MoS2 nanospheres were successfully fabricated by one-step hydrothermal approach using TiO2 as the precursor, and systematically investigated by various characterization methods (e.g. XRD, SEM, TEM and XPS analysis). Moreover, the tribological experiments of liquid paraffin contained TiO2, MoS2, and TiO2@MoS2 nano-additives were comparatively investigated by a ball-plate wear instrument, which tribological variables include applied load and rotational speed. TiO2@MoS2 as an additive in base oil exhibited superior antifriction and wear resistant among various nano-additives. At the optimal conditions, 5%-TiO2@MoS2-paraffin samples show the lower friction coefficient (~0.08) compared with pure paraffin, and paraffin contained TiO2 and/or MoS2. Additionally, the excellent anti-friction and wear-resistant of TiO2@MoS2 in base oil would be beneficial for the design of novel MoS2-based nano-additives for improving tribological performance in the industry and agriculture.

Enhanced reversible sodium storage by thin carbon layer encapsulated MoS2 nanospheres on interwoven carbon nanotubes

Here, an effective approach to obtain controllable thin carbon layer encapsulated MoS2 nanospheres on the surface of interwoven carbon nanotubes to form interconnected network structure of C-MoS2/CNTs composites is presented by a facile hydrothermal method. The remarkable electrochemical performance of the resulting composites as anode electrode materials are achieved for Na-ion energy storage systems, such as excellent capacity (~468 mA h g−1 at 1.0 A g−1), high rate capability (capacity retention of ~72.8% from 0.1 A g−1 to 5.0 A g−1) and long cycling stability (100.0% capacity remaining after 1000 cycles). Systematic characterizations reveal that the outstanding performance is mainly attributed to the unique and robust composite architecture, such as, improvement the conductivity of the whole electrode material, preventing the aggregation of C-MoS2 during cycles, large atomic interface contact for Na+ storage, and providing a dense porous space to alleviate volume expansion during cycling.

Nanosheet-assembled 3D flower-like MoS2/NiCo(OH)2CO3 composite for enhanced supercapacitor performance

3D flower-like MoS2/NiCo(OH)2CO3 (MoS2/NiCoHC) composites are synthesized by a hydrothermal method using MoS2 nanospheres as precursors. The microstructure of the composite is characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The MoS2 nanospheres are served as nucleating agent to trigger the formation of NiCoHC nanosheets, which self-assemble into 3D flower-like MoS2/NiCoHC particles. The MoS2/NiCoHC composites exhibit a high supercapacitive performance with a specific capacity of 583 C g−1 (1296 F g−1) at 1 A g −1 and a long-term cycling stability by retaining 94.3% after 2000 cycles in 2 M KOH. Moreover, the asymmetric supercapacitor of MoS2/NiCoHC as the positive electrode and commercial active carbon as the negative electrode achieves a high power density of 375 W kg−1 at 16.4 Wh kg−1. The enhanced performance of the MoS2/NiCoHC composite can be attributed to the larger surface area provided by 3D flower-like structure and the synergy of the two hybrids.

Oxygen and nitrogen-enriched hierarchical MoS2 nanospheres decorated cornstalk-derived activated carbon for electrocatalytic degradation and supercapacitors

In this work, Oxygen and nitrogen-enriched hierarchical MoS2 nanospheres decorated cornstalk-derived activated carbon (MoS2/CSAC) were prepared by simple carbonization and hydrothermal methods, being used in electrochemical advanced oxidation processes (EAOPs) and supercapacitors. The structure and electrochemical performance of MoS2/CSAC composites were analyzed in detail. Oxygen and nitrogen-enriched MoS2 is spherical with uniform size, and accumulation of nanosheets was observed on the surface. The unique hierarchical structure could contribute to form more catalytic active sites. MoS2/CSAC composites contain abundant mesopores and a wide range of pore sizes, which are beneficial for fast electrochemical reactions. Moreover, it was detected that the coexistence of Mo4+ and Mo6+ in the MoS2/CSAC composites, exhibiting high catalytic activity for accelerating the formation of •OH from H2O2. The degradation efficiency of phenol (100 mg L−1) is up to 97.26% in 120 min. Simultaneously, it showed excellent performance in supercapacitors. The specific capacitance was as high as 332.62 F g−1 in a three-electrode system. These results demonstrate that the MoS2/CSAC composites are promising dual-functional materials for electrocatalytic degradation and supercapacitors.

Controllable fabrication and structure evolution of hierarchical 1T-MoS2 nanospheres for efficient hydrogen evolution

The layered materials have demonstrated great prospects as cost-effective substitutes for precious electrocatalysts in hydrogen evolution reaction. Research efforts have been devoted to synthesizing highly conductive MoS2 with the substantial cardinal plane and edge active sites. Here, we successfully synthesized a hierarchical 1T/2H–MoS2 with sodium ion insertion via a facile hydrothermal method. The contents of the 1T-phase can be flexibly controlled by different hydrothermal temperatures (160 ∼ 200 °C). And the modified uniformly dispersed 1T/2H–MoS2 nanospheres with different d spacings were designed to enhance the electrocatalytic efficiency by adding SiO2 and through the ion exchange process of NaOH and HF solution. The as-synthesized Na+ intercalated 1T-MoS2 nanosphere with an expanded interlayer of 0.95 nm obtained at 160 °C exhibits a prominent electrocatalytic performance of hydrogen evolution reaction with a comparable overpotential of 255 mV and a remarkably small Tafel slope of 44 mV/decade. Therefore, this study provides a facile and controllable strategy to yield interlayer-expanded 1T-MoS2 nanospheres, making it a potentially competitive hydrogen evolution catalyst for the hydrogen cell.

Facile synthesis of biocompatible L-cysteine-modified MoS2 nanospheres with high photothermal conversion efficiency for photothermal therapy of tumor.

Photothermal therapy (PTT) can take advantage of the photothermal effects of photothermal agents to acquire the energy from laser irradiation and convert it into heat. This can intensively elevate the temperature of the surrounding environment to directly destroy the cancer cells. It is expected that PAs with strong absorption in near infrared (NIR) range might possess the ideal tissue-transparent feature and minimal damage to surrounding healthy tissues, beneficial to the practical application. Herein, well-dispersed L-cysteine modified MoS2 (MoS2-Cys) nanospheres with the average diameter of about 422nm and strong NIR adsorption were successfully synthesized through a facile method. The as-prepared MoS2-Cys nanospheres are composed of nanosheets with the average thickness of about 13.7nm. The photothermal conversion efficiency of the as-prepared MoS2-Cys nanospheres with the very low concentration of 50μg/mL was determined to be 35% when exposed to 808 NIR laser at the power density of 0.8W/cm2, much higher than those of the previous reports with same dose and power density. MoS2-Cys nanospheres possessed the good photothermal ablation effect to significantly inhibit the growth of tumor in vivo. Furthermore, MoS2-Cys nanospheres did not exhibit detectable side effects, suggesting their good in vitro and in vivo biocompatibility.

Synthesis and electrorheological properties of hierarchical and core-shell MoS2@TiO2 nanocomposite

MoS2@TiO2 nanocomposite with core-shell and hierarchical structure was synthesized using a simple and effective two-step method. First, 3D radically oriented MoS2 nanospheres were initially synthesized using a simple and convenient hydrothermal method to provide a large surface and active site for the uniform TiO2 growth on MoS2. Then, the structure, morphology, composition and electrorheological (ER) properties were characterised using an X-ray powder diffractometer, Fourier infrared spectrometer, transmission electron microscopy, scanning electron microscope with an attached energy-dispersive spectrometer, X-ray photoelectron spectroscopy and ER rheometer. The MoS2@TiO2 nanocomposite was dispersed into insulating silicone oil to form an ER fluid at a concentration of 10 ​wt %, which shown an enhanced ER efficiency by combining the useful of two dimensional MoS2 multistage structures and coating TiO2 shell to control conductivity. The large dielectric constant mismatch and short relaxation time of ER fluid was observed, which resulted in the creation of multiple polarizations and enhanced ER properties.

Different Morphology MoS2 Over the g-C3N4 as a Boosted Photo-Catalyst for Pollutant Removal Under Visible-Light

The nano-spherical MoS2(F)/g-C3N4 hetero-junction was successfully synthesized by calcining the thiourea coated MoS2(F), where the thin g-C3N4 nano-sheets were grown on the surface of MoS2(F) nano-sphere. The enhanced photo-catalytic performance and stability of the sample were assessed by degrading the Rhodamine B under the irradiation of sunlight, which could be attributed to the widened spectral absorption range and improved electron–hole separation rate. Based on above results, the photo-catalytic mechanism involving redox reactions was also proposed.