MoS2 Nanoflowers Research Articles

Magnetic Fe3O4 supported MoS2 nanoflowers as catalyst for the reduction of p-nitrophenol and organic dyes and as an electrochemical sensor for the detection of pharmaceutical samples

In the present study, Fe3O4 nanoparticles (NPs) supported MoS2 nanoflowers (Fe3O4–MoS2) are prepared by a simple and eco-friendly hydrothermal method and are well-characterized for their structure, morphology, size, phase composition, and magnetic property using XRD, FT‐IR, SEM, EDX, HR-TEM, SEM-elemental mapping and VSM techniques. As prepared Fe3O4–MoS2 showed good catalytic activity for the reduction of p-nitrophenol (p-NP), methylene blue (MB), and methyl orange (MO) dyes in the presence of NaBH4 in 10 min, 2 min, and 2 min with rate constants of 0.15 min−1, 0.88 min−1 and 0.53 min−1 respectively. Moreover, the Fe3O4–MoS2 catalyst was recovered magnetically in good yield and the recovered catalyst also showed a similar catalytic efficacy even up to nine cycles. Further, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements for Fe3O4–MoS2 electrode were performed in 1 M KOH aqueous electrolytes with (+0.50, −0.73 V) and (+0.10, −0.68 V) oxidation and reduction peaks in the reversible redox process respectively. The electrode exhibited a specific capacitance of 1.42 F g−1 basic electrolyte. EIS measurements showed a reduction in the charge transfer resistance. Modified carbon paste electrode using Fe3O4–MoS2 is used as a sensor for the detection of paracetamol (PCM), ascorbic acid (AA), hydrogen peroxide (HP), and tetracycline (TC) pharmaceutical samples, which showed well-separated peaks. These results indicate that the prepared Fe3O4–MoS2 has great potential to be developed as a catalyst and electrochemical sensor material for industrial applications.

High-Efficiency CdSe Quantum Dots/Fe3O4@MoS2/S2O82- Electrochemiluminescence System Based on a Microfluidic Analysis Platform for the Sensitive Detection of Neuron-Specific Enolase.

In this work, based on electrochemiluminescence (ECL) technology and self-assembled portable disease detection chips, a bioactivity-maintained sensing platform was developed for the quantitative detection of neuron-specific enolase. First, we prepared Fe3O4@MoS2 nanocomposites as an efficient catalyst to accelerate the reduction of persulfate (S2O82-). Specifically, abundant sulfate radicals (SO4•-) were generated because of cyclic conversion between Fe2+ and Fe3+. Meanwhile, MoS2 nanoflowers with a high specific surface area could not only load more Fe3O4 but also solve its agglomeration problem, which greatly improved the catalytic efficiency. Moreover, a biosensor chip was constructed by standard lithography processes for disease detection, which had good sensitivity and portability. According to the above strategies, the developed portable sensing platform played the part of promoting the practical application of bioanalysis in early tumor screening and clinical diagnosis. In addition, we developed a short peptide ligand (NARKFYKG, NAR) to avoid the occupation of antigen binding sites by specifically connecting to Fc fragments in antibodies. Thus, the binding efficiency of antibodies and the activity of biosensors were improved due to the introduction of NAR.

Fabrication of multiwall carbon nanotubes decorated with MoS2 nanoflowers for adsorption of Ag(I) from aqueous solution

In this work, a facile solvothermal method was employed to fabricate multiwall carbon nanotubes (MWCNTs) decorated with MoS2 nanoflowers (MoS2/MWCNTs) nanohybrid using carboxylation multiwall carbon nanotubes (MWCNTs-COOH) as skeleton for MoS2 in-situ growth, and the MoS2/MWCNTs nanohybrid was used as a novel sorbent to adsorb Ag(I) from aqueous solution. The structures and components of the obtained samples before and after adsorption were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), zeta potential analyzer and N2 adsorption-desorption isotherms. Meanwhile, the effect of solution pH, initial concentrations of Ag(I), contact time and temperature on the adsorption performance of the MoS2/MWCNTs nanohybrid for Ag(I) in aqueous solution were explored by batch experiments. The results show that MoS2 was decorated on MWCNTs in nanoflower-like structure, which could avoid agglomeration of MWCNTs and MoS2, expose as much of the sulfur-rich surface as possible, and provide abundant adsorption sites and transport channels for Ag(I) ions. The specific surface area of the MoS2/MWCNTs nanohybrid was 4.5 times that of pure MoS2. At the optimal adsorption conditions, the maximum adsorption capacity of the MoS2/MWCNTs nanohybrid for Ag(I) was 601.97 mg/g. The formation of Ag2S was main contribution for the adsorption, besides that, there was electrostatic adsorption. Based on the advantages of the simple synthesis method and high adsorption capacity, the MoS2/MWCNTs nanohybrid could be a promising candidate material for Ag(I) removal from wastewater.

Hydrochloric Acid-Assisted Synthesis of Highly Dispersed MoS2 Nanoflowers as the Cathode Material for Mg-Li Batteries

The layered material MoS2 has significant potential as a cathode material for hybrid Mg2+/Li+ batteries (MLIBs) due to its fast two-dimensional ion diffusion channel. However, the low capacity and poor cycling stability limit the practical application of MoS2. Herein, highly dispersed MoS2 nanoflowers with a large Brunauer–Emmett–Teller (BET) area of 118.25 m2 g–1 and a large lattice spacing of 0.65 nm are synthesized by a one-step hydrothermal method. The obtained MoS2 nanoflowers deliver a remarkable reversible capacity of 321 mA h g–1 at 0.1 A g–1. Notably, it displays an impressive cycling stability with a reversible capacity of 103 mA h g–1 over 600 consecutive cycles at 1 A g–1. The favorable electrochemical properties of the MoS2 are attributed to the large BET area and increased lattice spacing that are more conducive to the full contact between the electrolyte and the material, thus promoting the diffusion of ions and improving the reaction kinetics. The results of the present study offer an idea to prepare highly dispersed MoS2 with enhanced capacity and durability.

MoSe2 nanoflowers as a counter electrode for quantum dots sensitized solar cells

MoSe2 nanoflowers as a counter electrode for quantum dots sensitized solar cells

Symbiosis of 1 T and 2H phases in the basal plane of defective MoS2 nanoflowers for efficient hydrodesulfurization

Hydrodesulfurization (HDS) is an effective way to reduce sulfur content in oil for the enforcement of more stringent environmental regulations. MoS2 has been widely used as an effective component for catalyzing HDS, and needs to be extensively studied in depth. Herein, MoS2 nanoflowers with the symbiosis of 1T-2H phases in the basal planes and coexistence of S and Mo vacancies are prepared via the assembly of many nanosheets by a one-pot solvothermal method. The morphology, crystal phase structure and defects of these 1T-2H MoS2 samples were well characterized. The 1T/2H ratio and the state of vacancies were effectively tuned by changing the solvothermal conditions. Active and stable 1T-2H mixed MoS2 nanoflowers with high content of 1T phase and moderate S and Mo vacancies were obtained by the regulation of oxalic acid in the mixture of ethanol and water. In the HDS of dibenzothiophene at 300 °C and 4 MPa, the optimal catalyst of MoS2-water–ethanol-OA exhibited a substrate conversion of 89.3% in 10 h. Moreover, the activity of MoS2-water–ethanol-OA was well retained without any decrease in the recycling experiment.

Ultrasensitive electrochemical detection of bisphenol A using composites of MoS2 nanoflowers, CoS2 nano-polyhedrons and reduced graphene oxide

Ultrasensitive electrochemical detection of bisphenol A using composites of MoS2 nanoflowers, CoS2 nano-polyhedrons and reduced graphene oxide

High-efficiency cycling piezo-degradation of organic pollutants over three liters using MoS2/carbon fiber piezocatalytic filter

Piezocatalysis has great potential commercial application for the high-efficiency degradation of organic pollutants in a dark environment. However, the recycling of catalyst materials and the subsequent generation of secondary pollution remain challenging. In this study, MoS2 nanoflowers (NFs)/carbon fiber was synthesized to develop a piezocatalytic filter that can recycle decomposed wastewater easily without generating secondary pollutants in treated water. The MoS2/carbon fiber was constructed in pipelines to form the piezoelectric degradation system, which demonstrated a high efficiency in decomposing organic molecules in wastewater through natural water flow. The piezocatalytic filters in the circulatory system completely degraded a large amount of dye solution (1000 mL) in 40 min and can repeat three-times degradation with the total organic carbon value decreased by 90%. The theoretical calculation indicated that MoS2 grew on carbon fiber, which exhibited a bending moment effect under natural water-flow-induced pressure. This established considerable piezoelectric potential at MoS2 NFs active edge sites and MoS2–carbon fiber interfaces, triggering electron–hole pair separation under the internal electric field. The MoS2/carbon fiber piezoelectric catalyst is advantageous for its reusability and recyclability, thus preventing secondary pollution and adverse effects on water bodies during practical high-flux wastewater treatment.

Photothermal properties of two-dimensional molybdenum disulfide (MoS2) with nanoflower and nanosheet morphology

PEGylated MoS2 nanoflower (MoS2-NF) and nanosheet (MoS2-NS) are synthesized through a one-pot hydrothermal method as photo absorbing agent (PAA). It is found that employing different thiol precursors result in distinct morphologies. The products are structurally, chemically, and morphologically characterized. Electron microscopy demonstrates the formation of sheet and flower morphologies of MoS2. Fourier transform infrared (FTIR) and thermal gravimetric (TGA) analysis confirm the PEGylation of MoS2 nanostructures. Raman and X-ray photoelectron spectroscopy (XPS) confirm the formation of 1T/2H structure of both samples. MoS2-NS demonstrates higher NIR absorption than MoS2-NF with a mass extinction coefficient of 19.06 and 5.09 L/g.cm, respectively. The photothermal conversion efficiency (η) of MoS2-NF and MoS2-NS is 13.77% and 25.68%, respectively which can be due to the higher 1T to 2H ratio of MoS2-NS. Finally, MoS2-NS has significantly higher photo-to-heat conversion ability in comparison with MoS2-NF which makes it more suitable as PAA for photothermal therapy of tumors.

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.

A simple method for synthesizing Co, P-codoped MoS2 nanoflowers as electrocatalysts to enhance hydrogen evolution reaction

A simple method for synthesizing Co, P-codoped MoS2 nanoflowers as electrocatalysts to enhance hydrogen evolution reaction

MoS2 nano-flower incorporation for improving organic-organic solid state electrochromic device performance

A solid state electrochromic device has been fabricated using molybdenum disulfide (MoS2) doped Ethyl viologen (EV) and polythiophene (P3HT) layers. The MoS2 nano flower has been synthesized by one-step hydrothermal method and characterized by electron spectroscopy, X-ray diffraction and Raman spectroscopy. The prepared solid state electrochromic device shows its improved electrochromic performance like switching speed, cycle life and coloration efficiency while showing color modulation between magenta and blue colors. A very small external (±1.4 V) bias is sufficient to switch the device very quickly by taking time as low as 400 ms and shows the transmittance modulation of 42%. It is proposed that the MoS2 having graphene like 2D layered structure and the weak van der Waals force present between layers facilitates large amount of charge movement between the film and electrolyte, hence, promoting the high transfer rate of electrons, which plays the key role to enhance the performance of electrochromic device. Incorporation of MoS2 makes one of the most efficient devices in the family of polythiophene-viologen based devices and opened up a new avenues for other hybrid electrochromic device as graphene alternatives by exhibiting coloration efficiencies of as high as 580 cm2/C.

Polarization loss-enhanced honeycomb-like MoS2 nanoflowers/undaria pinnatifida-derived porous carbon composites with high-efficient electromagnetic wave absorption

The increasingly serious electromagnetic pollution has caused an urgent demand for easy preparation, sustainable and low-cost electromagnetic absorbing materials with super absorption capacity. Herein, inspired by the nature, spherical MoS2 nanoflowers/undaria pinnatifida-derived honeycomb-like porous carbon composites were fabricated by a simple carbonization and subsequent hydrothermal process. The unique honeycomb-like porous microstructure of undaria pinnatifida facilitates the generation of multiple scattering and reflections and the construction of interconnected conducting networks, while the rich porous structure provides a vast surface for the growth of MoS2 crystals. In addition, MoS2 significantly not only improved the impedance matching of the composites but also greatly enhanced the polarization loss due to the simultaneous growth of MoS2 nanoflowers on the surface and in the internal pores of the undaria pinnatifida. As a result, the hybrids achieved a maximum electromagnetic wave (EMW) absorption capacity with a reflection loss (RL) value of up to −75.94 dB at a thickness of only 1.68 mm. The results indicated that the C/MoS2 hybrids can be a new prospective candidate as sustainable EMW absorbers with low density and superb EMW absorption performance.

Synthesis of MoS2 nanoflowers on CdS nanorods with a simple route and their application in removal of dyes

Synthesis of MoS2 nanoflowers on CdS nanorods with a simple route and their application in removal of dyes

MoS2/Mo2TiC2Tx supported Pd nanoparticles as an efficient electrocatalyst for hydrogen evolution reaction in both acidic and alkaline media

Development of electrocatalytic hydrogen production technology is the key to solving environmental and energy problems. Two-dimensional material Mo2TiC2Tx (Tx = –OH, –F) has shown great potential in electrocatalytic hydrogen evolution because of its excellent conductivity and hydrophilicity. However, due to the lack of sufficient active sites of Mo2TiC2Tx itself, its practical applications in electrocatalytic hydrogen evolution are limited. In this work, a highly-efficient hydrogen evolution electrocatalyst, namely [email protected]2/Mo2TiC2Tx, is prepared through a simple pyrolysis method. In such a composite, the MoS2 nanoflowers hybridized with the ammonia-treated Mo2TiC2Tx (MoS2/Mo2TiC2Tx) are used as a substrate for loading a small number of Pd nanoparticles (4.27 at.%). Notably, the introduction of Pd nanoparticles into MoS2/Mo2TiC2Tx provides abundant active sites for the hydrogen evolution reaction, improves the conductivity of the electrocatalyst, speeds up the adsorption and desorption of hydrogen, and induces a synergistic effect with the MoS2. As a result, the [email protected]2/Mo2TiC2Tx catalyst exhibits excellent electrocatalytic performance and remarkable stability in both acidic and alkaline media. In a 0.5 mol/L H2SO4 electrolyte, the overpotential of [email protected]2/Mo2TiC2Tx was 92 mV with a Tafel slope of 60 mV/dec at a current density of 10 mA/cm2. Meanwhile, the catalyst displayed an overpotential of 100 mV associated with a Tafel slope of 80 mV/dec at the current density of 10 mA/cm2 in a 1 mol/L KOH electrolyte. This work shows the great potential of using Mo2TiC2Tx-based material in the field of electrocatalysis.

MoS2 nanoflowers decorated natural fiber-derived hollow carbon microtubes for boosting perfluorooctanoic acid degradation

Calotropis gigantea fiber (CGF) is a natural cellulose fiber with thin-walled large lumen. Benefitted from its unique structure, CGF was utilized here as a bio-template for the fabrication of hollow carbon microtubes using a facile hydrothermal method, and simultaneously, nano-sized MoS2 flowers were in-situ generated along the inner and outside surfaces of carbonized fiber microtubes, forming MoS2 nanoflowers decorated biochar MoS2/CGB. Coupled with dual active centers from non-metallic biochar and metallic MoS2, MoS2/CGB was then used for activating peroxymonosulfate (PMS) to degrade perfluorooctanoic acid (PFOA), one emerging pollutant that had received wide attention in recent years. The experimental results indicated that at room temperature and pH 3.0, MoS2/CGB exhibited the degradation efficiency of 79.6% for PFOA, and removal percentage of 50.7% for total organic carbon. During the degradation process, the free radical (SO4•−/•OH) and non-radical (1O2) routes coexisted, and the amount of SO4•− was about 9 times that of •OH. Combined with mass spectrometry, the possible degradation pathway of PFOA was proposed as transforming into short chained C2- to C5-containing carboxylic acids. With Vibrio fischeri as an indicator, the acute toxicity of PFOA solution and intermediates was evaluated, with the inhibition rate decreased from 27.6% to 4.5%. Finally, MoS2/CGB had the ability not only for removing perfluorinated compounds with different carbon chain lengths, but also for catalytically degrading PFOA in tap water and Yellow River water. This work provides plant fiber-based sustainable catalyst for potential application in PMS-based system for boosting PFOA degradation.

Controlled decoration of nanoceria on the surface of MoS2 nanoflowers to improve the biodegradability and biocompatibility in Drosophila melanogaster model

In recent years, nanozymes based on two-dimensional (2D) nanomaterials have been receiving great interest for cancer photothermal therapy. 2D materials decorated with nanoparticles (NPs) on their surface are advantageous over conventional NPs and 2D material based systems because of their ability to synergistically improve the unique properties of both NPs and 2D materials. In this work, we report a nanozyme based on flower-like MoS2 nanoflakes (NFs) by decorating their flower petals with NCeO2 using polyethylenimine (PEI) as a linker molecule. A detailed investigation on toxicity, biocompatibility and degradation behavior of fabricated nanozymes in wild-type Drosophila melanogaster model revealed that there were no significant effects on the larval size, morphology, larval length, breadth and no time delay in changing larvae to the third instar stage at 7–10 d for MoS2 NFs before and after NCeO2 decoration. The muscle contraction and locomotion behavior of third instar larvae exhibited high distance coverage for NCeO2 decorated MoS2 NFs when compared to bare MoS2 NFs and control groups. Notably, the MoS2 and NCeO2-PEI-MoS2 NFs treated groups at 100 μg ml−1 covered a distance of 38.2 mm (19.4% increase when compared with control) and 49.88 mm (no change when compared with control), respectively. High-resolution transmission electron microscopy investigations on the new born fly gut showed that the NCeO2 decoration improved the degradation rate of MoS2 NFs. Hence, nanozymes reported here have huge potential in various fields ranging from biosensing, cancer therapy and theranostics to tissue engineering and the treatment of Alzheimer’s disease and retinal therapy.

Enhanced visible Light-Driven photocatalytic hydrogen evolution and stability for noble Metal-Free MoS2/Zn0.5Cd0.5S heterostructures with W/Z phase junctions

A series of composite heterojunction-MoS2/Zn0.5Cd0.5S photocatalysts free of noble metal ions was prepared using a simple hydrothermal method. The X-ray diffraction spectra of the MoS2/Zn0.5Cd0.5S composites exhibit three strong intensive peaks, thereby explaining the existence of wurtzite (CdS) and zinc blende (ZnS) in the form of the wurtzite/zinc-blende phase junctions. Microstructural studies indicate that the sample displays a typical cubic crystal structure and that the MoS2 with flower-like structure uniformly wraps the granular Zn0.5Cd0.5S. X-ray photoelectron, Fourier transform infrared, and UV–Vis diffuse reflectance spectroscopic methods confirm that the heterojunction, which possesses outstanding photoresponse ability, is constructed between Zn0.5Cd0.5S nanoparticles and MoS2 nanoflowers. The fluorescence spectroscopy, surface photocurrent spectroscopy, and electrochemical studies indicate that Zn0.5Cd0.5S nanoparticles with specific amount of MoS2 nanoflowers can effectively suppress the recombination of photoinduced charge carriers of the composites. Therefore, pristine Zn0.5Cd0.5S nanoparticles loaded with 3%MoS2 exhibit optimum performance of hydrogen production (388.2 μmol/h), which is 1.3 times that of pristine Zn0.5Cd0.5S nanoparticles. A plausible mechanism for enhanced photocatalysis is provided in terms of the heterojunction assisted effective separation of charge carriers that are generated by irradiation.

Bifunctional Application of Viologen-MoS2-CNT/Polythiophene Device as Electrochromic Diode and Half-Wave Rectifier.

A dual purpose solid state electrochromic diode has been fabricated using polythiophene (P3HT) and ethyl Viologen (EV), predoped with multiwalled carbon nanotubes (MWCNTs) and MoS2. The device has been designed by considering two important aspects, first, the complementary redox activity of P3HT and EV and second, the electron holding properties of MoS2 and MWCNTs. The latter is found to enhance the electrochromic performance of the solid state device. On the other hand, the complementary redox nature gives the asymmetric diodic I-V characteristic to the device which has been exploited to use the electrochromic device for rectification application. The MoS2 nanoflower and MWCNTs are synthesized by one-step hydrothermal and pyrolysis techniques and well characterized by scanning electron microscopy (SEM), X-ray analysis (XRD), and Raman spectroscopy. Electrochromic properties of the device have been studied in detail to reveal an improvement in device performance in terms of faster speed and high coloration efficiency and color contrast. In situ bias-dependent Raman spectroscopy has been performed to understand the operation mechanism of the electrochromic diode which reveals (bi-)polaron formation as a result of dynamic doping eventually leading to color change. A half-wave rectifier has been realized from the electrochromic diode which rectifies an AC voltage of frequency 1 Hz or less making it suitable for low frequency operation. The study opens a new possibility to design and fabricate multipurpose frequency selective electrochromic rectifiers.

Oxygen-doped MoS2 nanoflowers with sulfur vacancies as electrocatalyst for efficient hydrazine oxidation

Direct hydrazine fuel cells (DHFCs) fuel has drawn significant attention due to its characteristics of high energy density. Substantial effort is still needed to explore sustainable and efficient catalysts for hydrazine oxidation reaction (HzOR). Herein, inspired by reducing solvents that can protect the precursors of nanomaterials from oxidation, oxygen-doped MoS2 nanoflowers with sulfur vacancies (O-rich MoS2) were prepared via a simple synthesis method using the readily available ethanol/water as the solvent and applied as electrocatalyst for HzOR. It is found that the ratio of ethanol to water has a significant influence on the morphology of MoS2 and the catalytic performance of hydrazine oxidation. Moreover, the concept of O-doping is proposed by introducing oxygen atoms to mostly replace bulk S atoms in the oxidation process of nanomaterials. The sulfur vacancy and doping were regarded as the main active site for the HzOR. Accordingly, the onset potential of the prepared electrocatalyst is 0.5 V vs. RHE in a 1 M KOH/0.1 M hydrazine electrolyte. This doping method can provide new ideas for improving the construction of hydrazine oxidation catalysts in the future.