Disulfide Microspheres Research Articles

Preparation of molybdenum disulfide microspheres and their effect on the thermal conductivity of epoxy resin

Preparation of molybdenum disulfide microspheres and their effect on the thermal conductivity of epoxy resin

Facile Synthesis and Outstanding Supercapacitor Performance of Ternary Nanocomposite of Silver Particles Decorated N/S Dual-Doped Graphene and MoS2 Microspheres Stabilized by Graphene Quantum Dots

The ternary nanocomposite of silver particles decorated N/S dual-doped graphene and molybdenum disulfide microspheres (Ag-MoS2/NSG) is prepared by hydrothermal-chemical reduction method with graphene quantum dots (GQDs) as additives and graphene oxide, sodium molybdate and silver nitrate as main raw materials. For comparison, the binary composites of Ag-MoS2, Ag-NSG and MoS2/NSG are also prepared and discussed. In addition, the physicochemical and electrochemical properties of GQDs are studied, and the dynamic analysis of Ag-MoS2/NSG is also carried out. Results show that the ternary composite of Ag, MoS2 and NSG can effectively prevent the lamellar superposition and agglomeration of graphene, which effectively improves the specific surface area and conductive properties of the composite. The specific capacitance of Ag-MoS2/NSG is 1124.3 F·g−1 at 10 mV·s−1, and the specific capacitance retention is 95.2% after 10000 constant current charge/discharge loops. The asymmetric button supercapacitor device assembled with NSG and Ag-MoS2/NSG has a maximum energy density of 82.5 Wh·kg−1 (900 W·kg−1).

Facile synthesis of flower-like P-doped nickel-iron disulfide microspheres as advanced electrocatalysts for the oxygen evolution reaction

Although phosphosulfide and P-doped sulfide materials have been widely reported as highly efficient electrocatalysts for the oxygen evolution reaction (OER), the practical application of these materials is severely hindered by their complicated fabrication method. This paper reports a facile preparation of 3D hierarchical flower-like P-doped Ni–Fe disulfide microspheres by successive hydrothermal and one-step phosphosulfidation, using P2S5 as a source of phosphorus (P) and sulfur (S). Owing to the synergistic effect of the binary metal system, the introduction of P, and unique 3D porous architecture, the flower-like P-doped Ni–Fe disulfide microspheres deliver outstanding OER performance—an overpotential of 264 mV to achieve a current density of 10 mA cm−2, a significantly low Tafel slope of 48 mV dec−1, and excellent long-term durability over 50 h with negligible degradation in alkaline media. The fabrication method applied in this study can provide a new facile approach to the design and synthesis of P-doped metal sulfide materials for various electrochemical applications.

Construction of few layered metallic MoS2 microspheres using glucose induced carbon spheres and its application in symmetric supercapacitor device

Abstract Metallic molybdenum disulfide microspheres are constructed by successful growth of ultrathin 1 T-MoS2 nanosheets over carbon spheres in a controlled manner, as a framework to provide large electrochemically active sites. The developed metallic 1 T-MoS2/carbon microspheres enhance the electrochemical energy storage efficiency, where the carbon acts as a conductive backbone to the structure and facilitates smooth charge transfer kinetics during charge-discharge. The reduced number of layers on the 1 T-MoS2/carbon microspheres obviously decreases the restacking tendency of individual MoS2 nanosheets, which in turn reduces the degree of agglomeration. Here, the microsphere electrode material exhibits a high specific capacity (capacitance) of 346C/g (692 F/g) at a specific current of 1 A/g in three-electrode studies. The electrode maintains high capacity retention of 50% when there is a 10 fold increment in the current. The practicability of the electrode material is tested by designing a two-electrode symmetric device, and which delivers a high energy density of 46 Wh/kg with a power density of 775 W/kg. This symmetric cell provides 87% capacity retention over 20,000 charge/discharge cycles, implying its high stability. This nano-architecture promises a new strategy for synthesizing efficient metallic MoS2 based electrode materials for energy storage applications.

Morphology and surface chemistry engineering toward pH-universal catalysts for hydrogen evolution at high current density

Large-scale implementation of electrochemical hydrogen production requires several fundamental issues to be solved, including understanding the mechanism and developing inexpensive electrocatalysts that work well at high current densities. Here we address these challenges by exploring the roles of morphology and surface chemistry, and develop inexpensive and efficient electrocatalysts for hydrogen evolution. Three model electrocatalysts are flat platinum foil, molybdenum disulfide microspheres, and molybdenum disulfide microspheres modified by molybdenum carbide nanoparticles. The last catalyst is highly active for hydrogen evolution independent of pH, with low overpotentials of 227 mV in acidic medium and 220 mV in alkaline medium at a high current density of 1000 mA cm−2, because of enhanced transfer of mass (reactants and hydrogen bubbles) and fast reaction kinetics due to surface oxygen groups formed on molybdenum carbide during hydrogen evolution. Our work may guide rational design of electrocatalysts that work well at high current densities.

Facile synthesis of pristine FeS2 microflowers and hybrid rGO-FeS2 microsphere electrode materials for high performance symmetric capacitors

Iron pyrite (FeS2) is an interesting mineral in the transition metal dichalcogenide group due to its high abundance in the earth’s crust which can be used for various electrochemical energy storage applications, such as batteries and supercapacitors; however, it suffers from low rate capability and poor cycle performance, which hampers its use from large-scale commercial applications. In the present study, iron disulfide microspheres anchored onto a reduced graphene oxide matrix (rGO-FeS2 hybrid) were grown using a superficial hydrothermal method. For comparison, rGO-free iron disulfide material was synthesized under the same hydrothermal conditions, and uniformly distributed FeS2 micro-size flowers were formed. The energy storage capacity of both electroactive materials (FeS2 and rGO-FeS2 hybrid material) was tested for supercapacitor applications in a symmetric cell configuration. The pristine FeS2 microflower electrode exhibited an areal capacitance of 70.98mFcm−2 at 5mVs−1. On the other hand, the rGO-FeS2 hybrid microsphere electrode exhibited an enhanced areal capacitance of 112.41mF cm−2 at the same scan rate with an excellent capacitance retention of 90% over 10,000 cycles. The improved electrochemical performance of the rGO-FeS2 hybrid material is due mainly to its improved electrical conductivity, high surface area indicating an enhanced electron, and ion transfer mechanism. This study suggests that the rGO-FeS2 hybrid electrode material has potential applications in energy storage devices.

Hydrothermal synthesis of flower-like molybdenum disulfide microspheres and their application in electrochemical supercapacitors.

Three-dimensional flower-like molybdenum disulfide microspheres composed of nanosheets were prepared by a hydrothermal method using ammonium molybdate as the molybdenum source and thiourea as the sulfur source. Structural and morphological characterizations were performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of MoS2 electrode were studied by performing cyclic voltammetry (CV), galvanostatic charge–discharge analysis and electrochemical impedance spectroscopy (EIS). When used as an electrode material for supercapacitor, the hybrid MoS2 showed a high specific capacity of 518.7 F g−1 at a current density of 1 A g−1 and 275 F g−1 at a high discharge current density of 10 A g−1. In addition, a symmetric supercapacitor composed of MoS2 as positive and negative electrodes was prepared, which exhibited a high energy density of 12.46 W h kg−1 at a power density of 70 W kg−1 and still maintains an impressive energy density of 6.42 W h kg−1 at a large power density of 7000 W kg−1. The outstanding performance of the MoS2 electrode material indicates its great potential for applications in high-performance energy storage systems.

Facile synthesis of monodispersed yolk-shelled molybdenum disulfide microspheres with enhanced photocatalytic properties

Monodispersed yolk-shelled MoS2 microspheres with outstanding photocatalytic properties have been synthesized by the hydrothermal method with the assistance of P123.

Facile synthesis of MoS2/Fe3O4 nanocomposite with excellent Photo-Fenton-like catalytic performance

In this paper, a magnetic nanocomposite has been successfully synthesized by a hydrothermal route using magnetite nanoparticles (Fe3O4 NPs) and molybdenum disulfide microspheres (MoS2) as main raw materials. The ratio of Fe3O4 and MoS2 and reaction time on the shape and properties of the magnetic nanocomposite were investigated. Results showed that Fe3O4 nanoparticles can well bind on MoS2 microspheres when the concentration of Fe3O4 NPs and the reaction time were about 10 mg/L and 18 h. The visible light photocatalytic, Fenton-like catalytic and photo-Fenton-like catalytic performances of the as-prepared MoS2/Fe3O4 nanocomposite were comparatively evaluated by degradation of Rhodamine B (RhB), respectively. It was found that the MoS2/Fe3O4 nanocomposite exhibited excellent photo-Fenton-like catalytic degradation performance. The easy synthesis and separation, coupled with the excellent removal of organic dyes, make the MoS2/Fe3O4 nanocomposite an attractive catalyst for the purification of contaminated water.

Hydrothermal Synthesis and Characterization of Flowerlike Molybdenum Disulfide Microspheres

Hydrothermal Synthesis and Characterization of Flowerlike Molybdenum Disulfide Microspheres

Hierarchical MoS2 microspheres prepared through a zinc ion-assisted hydrothermal route as an electrochemical supercapacitor electrode

Hierarchical molybdenum disulfide microspheres have been successfully prepared through a zinc ion-assisted hydrothermal route followed by an acid corrosion strategy.

Synthesis of various carbon incorporated flower-like MoS2 microspheres as counter electrode for dye-sensitized solar cells

A flower-like molybdenum disulfide microspheres and various carbon materials (acetylene black, vulcan carbon, multi-walled carbon nanotubes, carbon nanofibers, and rice husk ash) incorporated MoS2 microsphere materials were synthesized via convenient single-step hydrothermal method. The obtained MoS2/C materials provide cost-effective and Pt free counter electrodes for DSSCs. Phthaloylchitosan-based polymer electrolyte was used as an electrolyte for DSSCs. The phase formation and purity of the synthesized materials were ascertained by powder X-ray diffractometer. The shape, morphology, and the distribution of the carbon materials in MoS2 microspheres were examined by electron microscope measurements. The electrochemical measurements were revealed that the carbon materials incorporated MoS2 electrode hold low charge transfer resistance at the counter electrode/electrolyte interface and demonstrate high electrocatalytic activity for the reduction of I3− to I−ions. Among different carbon materials studied, MoS2 doped on CNF offered a positive synergistic effect for the electrocatalytic reduction of I3−. The DSSC fabricated with MoS2/CNF CE and phthaloylchitosan-based polymer electrolyte shown a high power conversion efficiency of 3.17 %, whereas pure MoS2 CE showed only 1.04 %. The present study validates the application of carbon incorporated MoS2 as a potential CE in DSSCs.

Poly(3,4-ethylenedioxythiophene)/nickel disulfide microspheres hybrid in energy storage and conversion cells

The redox pseudocapacitive response of a hybrid material made up of NiS2 microspheres embedded in a poly(3,4-ethylenedioxythiophene) or (PEDOT) layer is demonstrated for the first time.

Biomolecule-assisted hydrothermal synthesis of molybdenum disulfide microspheres with nanorods

MoS 2 microspheres with nanorods were successfully synthesized by hydrothermal method at 240 °C for 24 h, employing sodium molybdate and L-cysteine as reactants. L-cysteine turned out to be served as both the sulfur source and the directing molecule in the formation of molybdenum disulfide nanostructures. The as-prepared MoS 2 was characterized by X-ray power diffraction (XRD), X-ray photoelectron spectrum (XPS), field-emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FT-IR). FE-SEM images showed that the product was microspheres, consisting of nanorods with length of about 100 nm. The possible formation mechanism was also discussed. The results indicated that MoO 2 was the metastable phase and Na 2MoO 4·2H 2O was converted to MoS 2 via MoO 2.

Facile Synthesis of Molybdenum Disulfide Micro-Spheres and the Tribological Properties in Liquid Paraffin

Well-dispersed MoS2 micro-spheres with the diameters of 0.5∼1.5 µm have been successfully synthesized via the extraction-solvothermal method. The ions were extracted into hexane by the extractant Cyanex 302 (di-(2,4,4-trimethylpentyl) monothiophosphinic acid) firstly, then the extracted solution was given solvothermal treatment to synthesize MoS2 at 150 °C for 24 hours. The obtained samples was characterized by XRD, EDS, SEM, TEM, and HRTEM technologies, respectively. Results indicated that Cyanex 302 acted as phase transferring agent, reductant, sulfur source and morphology-controlling agent in the whole procedure. Moreover, the tribological properties of liquid paraffin (LP) containing the as-prepared MoS2 micro-spheres were also evaluated on a four-ball machine and the chemical states of some typical elements on the worn surfaces were examined with XPS, showing that the MoS2 product was an excellent oil additive in LP with good anti-wear and friction-reducing properties.

A low-temperature extraction–solvothermal route to the fabrication of micro-sized MoS 2 spheres modified by Cyanex 301

Mono-dispersed molybdenum disulfide micro-spheres with the diameter of 1–3 μm have been successfully synthesized via extraction–solvothermal method at 150 °C. The extractant Cyanex 301 (di-(2,4,4-trimethylpentyl) dithiophosphinic acid) acted as phase transferring agent, reductant, sulfur source and morphology-controlling agent in the whole procedure. The obtained MoS 2 micro-spheres were characterized by XRD, EDS, SEM, TEM, HRTEM, IR, UV-Vis and TG, respectively. The influences of reaction conditions were discussed while a mechanism was proposed to explain the formation of the micro-spheres. Moreover, the tribological properties of liquid paraffin (LP) containing Cyanex 301-modified MoS 2 micro-spheres were also evaluated on a four-ball machine, showing that the obtained MoS 2 product was an excellent oil additive in LP and such lubricant had good anti-wear and friction-reducing properties.