Preparation of MoS2-based polydopamine-modified core–shell nanocomposites with elevated adsorption performances

New molybdenum disulfide (MoS₂)-based core–shell nanocomposite materials were successfully prepared through the self-assembly of mussel-inspired chemistry. Characterization by Fourier transform infrared, thermogravimetric analysis, scanning electron microscope and transmission electron microscopy revealed that the surface of the flaked MoS₂ was homogeneously coated with a thin layer of polydopamine (PDA). Dye adsorption performances of the synthesized MoS₂–PDA nanocomposites were investigated at different pH values and reaction times. Compared with pure MoS₂ nanosheets, the obtained core–shell nanocomposites showed elevated adsorption performances and high stability, indicating their potential applications in wastewater treatment and composite materials.

New core–shell MoS₂–PDA nanocomposites are prepared via mussel-inspired chemistry and a simple interfacial self-assembly process, demonstrating potential applications in wastewater treatment and self-assembled core–shell composite materials.     

Synergistic effect of Co–Ni co-bridging with MoS2 nanosheets for enhanced electrocatalytic hydrogen evolution reactions

The depletion of fossil fuels and associated environmental problems have drawn our attention to renewable energy resources in order to meet the global energy demand. Electrocatalytic hydrogen evolution has been considered a potential energy solution due of its high energy density and environment friendly technology. Herein, we have successfully synthesized a noble-metal-free Co–Ni/MoS₂ nanocomposite for enhanced electrocatalytic hydrogen evolution. The nanocomposite has been well characterized using HRTEM, elemental mapping, XRD, and XPS analysis. The as-synthesized nanocomposite exhibits a much smaller onset potential and better current density than those of Co–MoS₂, Ni–MoS₂ and MoS₂, with a Tafel value of 49 mV dec⁻¹, which is comparable to that of a commercial Pt/C catalyst. The synergistic effect and interfacial interaction of Co–Ni bimetallic nanoparticles enhances the intrinsic modulation in the electronic structure resulting in an improved HER performance. Moreover, the electrochemical impedance spectroscopic results suggest smaller resistance values for the Co–Ni/MoS₂ nanocomposite, compared to those for the charge transfer of bare nanosheets, which increase the faradaic process and in turn enhance the HER kinetics for a better performance. Our as-synthesized Co–Ni/MoS₂ nanocomposite holds great potential for the future synthesis of noble-metal-free catalysts.

A noble-metal-free Co–Ni/MoS₂ nanocomposite was synthesized, which showed enhanced electrocatalytic hydrogen evolution performance.     

MoS2 nanosheet mediated ZnO–g-C3N4 nanocomposite as a peroxidase mimic: catalytic activity and application in the colorimetric determination of Hg(ii)

A novel colorimetric sensing platform using the peroxidase mimicking activity of ternary MoS₂-loaded ZnO–g-C₃N₄ nanocomposites (ZnO–g-C₃N₄/MoS₂) has been developed for the determination of Hg(ii) ions over co-existing metal ions. The nanocomposite was prepared using an exfoliation process, and the product was further characterized using SEM, TEM, XRD and FTIR analysis. The ZnO–g-C₃N₄/MoS₂ possesses excellent intrinsic catalytic activity to induce the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in aqueous solution in the presence of H₂O₂ to generate deep blue coloured cation radicals (TMB⁺) which can be viewed with the naked eye and produce absorbance at a wavelength of 652 nm. The addition of a well known bioradical scavenger, glutathione (GSH), to the solution hinders the generation of cation radicals and turns the solution colourless. The introduction of Hg(ii) to this solution brings the blue colour back into it, due to the strong affinity of the thiol in the GSH. Based on this mechanism, we have developed a simple and rapid colorimetric sensor for the highly sensitive and selective detection of Hg(ii) ions in aqueous solution with a low detection limit of 1.9 nM. Furthermore, the prepared colorimetric sensor was effectively applied for the quantification analysis of real water samples.

A novel colorimetric sensing platform using the peroxidase mimicking activity of ternary MoS₂-loaded ZnO–g-C₃N₄ nanocomposites (ZnO–g-C₃N₄/MoS₂) has been developed for the determination of Hg(ii) ions over co-existing metal ions.     

Preparation of a MoS2/carbon nanotube composite as an electrode material for high-performance supercapacitors

MoS₂ and MoS₂/carbon allotrope (MoS₂/C) composites for use as anodes in supercapacitors were prepared via a facile hydrothermal method. In this study, we report the effects of various carbon-based materials (2D graphene nanosheet (GNS), 1D carbon nanotube (CNT), and 0D nano carbon (NC)) on the electrochemical performances. Among all nanocomposites studied, MoS₂/CNT exhibited the best electrochemical performance. Specifically, the MoS₂/CNT composite exhibits remarkable performances with a high specific capacitance of 402 F g⁻¹ at a current density of 1 A g⁻¹ and an outstanding cycling stability with 81.9% capacitance retention after 10 000 continuous charge–discharge cycles at a high current density of 1 A g⁻¹, making it adaptive for high-performance supercapacitors. The superiority of MoS₂/CNT was investigated by field emission scanning electron microscopy and transmission electron microscopy, which showed that MoS₂ nanosheets were uniformly loaded into the three-dimensional interconnected network of nanotubes, providing an excellent three dimensional charge transfer network and electrolyte diffusion channels while effectively buffering the collapse and aggregation of active materials during charge–discharge processes. Overall, the MoS₂/CNT nanocomposite synthesized by a simple hydrothermal process presents a new and promising candidate for high-performance anodes for supercapacitors.

The effect of carbon supports on the electrochemical performance of MoS₂ nanosheets for supercapacitor applications was investigated.     

CoFe2O4 nanoparticles decorated MoS2-reduced graphene oxide nanocomposite for improved microwave absorption and shielding performance

Magnetic CoFe₂O₄ nanoparticles decorated onto the surface of a MoS₂-reduced graphene oxide (MoS₂-rGO/CoFe₂O₄) nanocomposite were synthesized by a simple two-step hydrothermal method. The electromagnetic (EM) wave absorption performance and electromagnetic interference (EMI) shielding effectiveness of the materials were examined in the frequency range of 8.0–12.0 GHz (X-band). The MoS₂-rGO/CoFe₂O₄ nanocomposite was characterized by various tools such as X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. High-resolution transmission electron microscopy results confirmed the decoration of magnetic nanoparticles onto the surface of the MoS₂-rGO nanocomposite with a diameter of 8–12 nm. The multiple interfacial polarization, moderate impedance matching, and defect dipole polarization improve the dielectric and magnetic loss of the materials, which leads to strong attenuation loss ability of incident EM energy within the shield. The pure MoS₂-rGO nanocomposite represents total shielding effectiveness (SE_T ∼16.52 dB), while the MoS₂-rGO/CoFe₂O₄ nanocomposite exhibits total shielding effectiveness (SE_T ∼19.26 dB) over the entire frequency range. It may be explained that the magnetic nanoparticles (CoFe₂O₄) serve as excellent conductive and magnetic fillers with a large surface area, leading to the migration of charge carriers at multi-interfaces.

Magnetic CoFe₂O₄ nanoparticles decorated onto the surface of a MoS₂-reduced graphene oxide (MoS₂-rGO/CoFe₂O₄) nanocomposite were synthesized by a simple two-step hydrothermal method.     

Enhancing the chloramphenicol sensing performance of Cu–MoS2 nanocomposite-based electrochemical nanosensors: roles of phase composition and copper loading amount

The rational design of nanomaterials for electrochemical nanosensors from the perspective of structure–property–performance relationships is a key factor in improving the analytical performance toward residual antibiotics in food. We have investigated the effects of the crystalline phase and copper loading amount on the detection performance of Cu–MoS₂ nanocomposite-based electrochemical sensors for the antibiotic chloramphenicol (CAP). The phase composition and copper loading amount on the MoS₂ nanosheets can be controlled using a facile electrochemical method. Cu and Cu₂O nanoparticle-based electrochemical sensors showed a higher CAP electrochemical sensing performance as compared to CuO nanoparticles due to their higher electrocatalytic activity and conductivity. Moreover, the design of Cu–MoS₂ nanocomposites with appropriate copper loading amounts could significantly improve their electrochemical responses for CAP. Under optimized conditions, Cu–MoS₂ nanocomposite-based electrochemical nanosensor showed a remarkable sensing performance for CAP with an electrochemical sensitivity of 1.74 μA μM⁻¹ cm⁻² and a detection limit of 0.19 μM in the detection range from 0.5–50 μM. These findings provide deeper insight into the effects of nanoelectrode designs on the analytical performance of electrochemical nanosensors.

In this work, we clarify the roles of phase composition and copper loading amount on the CAP sensing performance of Cu–MoS₂ nanocomposite-based electrochemical nanosensors.     

Facile fabrication of water-dispersible nanocomposites based on hexa-peri-hexabenzocoronene and Fe3O4 for dual mode imaging (fluorescent/MR) and drug delivery

The facile fabrication of multifunctional nanocomposites (Fe₃O₄/HBC@F127) consisting of superparamagnetic Fe₃O₄ nanoparticles and fluorescent organic hexa-peri-hexabenzocoronene (HBC) molecules incorporated in block copolymer diacylphospholipid–polyethyleneglycol F127 have been demonstrated for dual mode imaging (fluorescent/MR) and drug delivery. The obtained nanocomposites were water-dispersible, stable and biocompatible, as confirmed by dynamic light scattering (DLS) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Relativity measurements showed a T₂ relaxivity (r₂) of 214.61 mM⁻¹ s⁻¹, which may be used as T₂-weighted MR imaging agents. In vitro imaging studies indicated that the nanocomposites had good MR and fluorescence imaging effects with low cytotoxicity. Besides, the developed nanocomposites could also be applied as drug delivery vehicles. Doxorubicin (DOX) loaded Fe₃O₄/HBC@F127 nanocomposites significantly inhibited the growth of human hepatoma cells (HepG2). These findings suggested that the facile synthesized multifunctional nanocomposites may be used as a platform for dual mode imaging (both MR and fluorescence) and drug delivery.

Water-dispersible, stable and biocompatible dandelion-like Fe₃O₄/HBC@F127 nanocomposites were facilely developed for dual mode imaging (fluorescent/MR) and drug delivery.     

Poly(3-hydroxybutyrate)/poly(amine)-coated nickel oxide nanoparticles for norfloxacin delivery: antibacterial and cytotoxicity efficiency

Sustained release dosage forms enable prolonged and continuous release of a drug in the gastrointestinal tract for medication characterized by a short half lifetime. In this study, the effect of blending polyamine on poly(3-hydroxybutyrate) (PHB) as a carrier for norfloxacin (NF) was studied. The prepared blend was mixed with different amounts of NiO nanoparticles and characterized using FTIR analysis, X-ray diffraction analysis, thermogravimetric analysis, dynamic light scattering, transmission electron microscopy and scanning electron microscopy. It was found that the drug released from the nanocomposite has a slow rate in comparison with NiO, PHB, and PHB/polyamine blend. The highest ratio of NiO content to the matrix (highest NF loading), leads to a slower rate of drug release. The release from the nanocomposites showed a faster rate at pH = 2 than that at pH = 7.4. The mechanisms of NF adsorption and release were studied on PHB/polyamine–3% NiO nanocomposite. In addition, the antimicrobial efficacy of nanocomposites loaded with the drug was determined and compared with the free drug. Inclusion of NiO into PHB/polyamine showed a higher efficacy against Streptococcus pyogenes and Pseudomonas aeruginosa than the free NF. Moreover, the cytotoxicity of PHB/polyamine–3% NiO against HePG-2 cells was investigated and compared with PHB and PHB/polyamine loaded with the drug. The most efficient IC₅₀ was found for NF@PHB/polyamine–3% NiO (29.67 μg mL⁻¹). No effect on cell proliferation against the normal human cell line (WISH) was observed and IC₅₀ was detected to be 44.95 and 70 μg mL⁻¹ for NiO nanoparticles and the PHB/polyamine–3% NiO nanocomposite, respectively indicating a selectivity of action towards tumor cells coupled with a lack of cytotoxicity towards normal cells.

PHB/poly(amine)-coated NiO nanoparticles for NOR delivery: antibacterial and cytotoxicity efficiency.     

A study on the tribological property of MoS2/Ti–MoS2/Si multilayer nanocomposite coating deposited by magnetron sputtering

Pure MoS₂ coatings are easily affected by oxygen and water vapor to form MoO₃ and H₂SO₄ which cause a higher friction coefficient and shorter service life. In this work, five kinds of MoS₂/Ti–MoS₂/Si multilayer nanocomposite coatings have been deposited by using unbalanced magnetron sputtering with different modulation period ratios. The tribological tests and nano-indentation experiments have been carried out in order to study the tribological and mechanical properties of the multilayer nanocomposite coating. The results show that the hardness and internal stress of the multilayer nanocomposite coatings are superior to those of the pure MoS₂ coating. The polycrystalline columnar structures are effectively inhibited and the coating densification increases due to the multilayer nanostructure and the doped elements of Ti and Si. The nanocomposite coating with a modulation period ratio of 100 : 100 shows the lowest friction coefficient and wear rate. The multilayer nanocomposite coatings exhibit excellent tribological property under a heavy constant load. Interfaces in multilayer nanostructure coating is able to hinder the dislocations motion and the crack propagation. The doped elements of Ti and Si with nano-multilayer structure enhances the mechanical and tribological properties of MoS₂ coating. This study provides guidelines for optimizing the mechanical and tribological properties of MoS₂ coating.

Pure MoS₂ coatings are easily affected by oxygen and water vapor to form MoO₃ and H₂SO₄ which cause a higher friction coefficient and shorter service life.     

Atmospheric-pressure-plasma-jet processed carbon nanotube (CNT)–reduced graphene oxide (rGO) nanocomposites for gel-electrolyte supercapacitors

This study evaluates DC-pulse nitrogen atmospheric-pressure-plasma-jet processed carbon nanotube (CNT)–reduced graphene oxide (rGO) nanocomposites for gel-electrolyte supercapacitor applications. X-ray photoelectron spectroscopy (XPS) indicates decreased oxygen content (mainly, C–O bonding content) after nitrogen APPJ processing owing to the oxidation and vaporization of ethyl cellulose. Nitrogen APPJ processing introduces nitrogen doping and improves the hydrophilicity of the CNT–rGO nanocomposites. Raman analysis indicates that nitrogen APPJ processing introduces defects and/or surface functional groups on the nanocomposites. The processed CNT–rGO nanocomposites on carbon cloth are applied to the electrodes of H₂SO₄–polyvinyl alcohol (PVA) gel-electrolyte supercapacitors. The best achieved specific (areal) capacitance is 93.1 F g⁻¹ (9.1 mF cm⁻²) with 15 s APPJ-processed CNT–rGO nanocomposite electrodes, as evaluated by cyclic voltammetry under a potential scan rate of 2 mV s⁻¹. The addition of rGOs in CNTs in the nanoporous electrodes improves the supercapacitor performance.

This study demonstrates ultrafast (15 s) atmospheric-pressure-plasma-jet (APPJ) processed CNT–rGO nanocomposite gel-electrolyte supercapacitors.     

Thiolated poly(aspartic acid)-functionalized two-dimensional MoS2, chitosan and bismuth film as a sensor platform for cadmium ion detection

In this work, a sensitive electrochemical platform for determination of cadmium ions (Cd²⁺) is obtained using thiolated poly(aspartic acid) (TPA)-functionalized MoS₂ as a sensor platform by differential pulse anodic stripping voltammetry (DPASV). The performance of the TPA–MoS₂-modified sensor is systemically studied. It demonstrates that the TPA–MoS₂ nanocomposite modified sensor exhibits superior analytical performance for Cd²⁺ over a linear range from 0.5 μg L⁻¹ to 50 μg L⁻¹, with a detection limit of 0.17 μg L⁻¹. Chitosan is able to form a continuous coating film on the surface of the GC electrode. The good sensing performance of the TPA–MoS₂-modified sensor may be attributed to the following factors: the large surface area of MoS₂ (603 m² g⁻¹), and the abundant thiol groups of TPA. Thus, the TPA–MoS₂-modified sensor proves to be a reliable and environmentally friendly tool for the effective monitoring of Cd²⁺ existing in aquacultural environments.

In this work, a sensitive electrochemical platform for determination of cadmium ions (Cd²⁺) is obtained using thiolated poly(aspartic acid) (TPA)-functionalized MoS₂ as a sensor platform by differential pulse anodic stripping voltammetry (DPASV).     

A facile synthesis of a cobalt nanoparticle–graphene nanocomposite with high-performance and triple-band electromagnetic wave absorption properties

Ferromagnetic metal nanoparticle/graphene nanocomposites are promising as excellent electromagnetic (EM) wave absorption materials. In this work, we used a facile method to synthesize a cobalt nanoparticle–graphene (CoNP–G) nanocomposite. The obtained CoNPs–G exhibited a saturation magnetization (M_s) of 31.3 emu g⁻¹ and a coercivity (H_C) of 408.9 Oe at 298.15 K. In particular, the CoNPs–G nanocomposite provided high-performance EM wave absorption with multiband, wide effective absorption bandwidth, which was mainly attributed to the synergy effects generated by the magnetic loss of cobalt and the dielectric loss of graphene. In the range of 2–18 GHz, the sample (55 wt% CoNPs–G) held three effective reflection loss (RL) peaks (frequency ranges of 2.4–3.84, 7.84–11.87 and 13.25–18 GHz, respectively, RL ≤ −10 dB) with the coating thickness of 4.5 mm, and the effective bandwidth reached the maximum of 10.22 GHz, and the minimal RL reached −40.53 dB at 9.50 GHz. Therefore, the CoNPs–G nanocomposite presents a great promising application in the electromagnetic wave absorption field.

Ferromagnetic metal nanoparticle/graphene nanocomposites are promising as excellent electromagnetic (EM) wave absorption materials.     

A stable TiO2–graphene nanocomposite anode with high rate capability for lithium-ion batteries

A rapid microwave hydrothermal process is adopted for the synthesis of titanium dioxide and reduced graphene oxide nanocomposites as high-performance anode materials for Li-ion batteries. With the assistance of hydrazine hydrate as a reducing agent, graphene oxide was reduced while TiO₂ nanoparticles were grown in situ on the nanosheets to obtain the nanocomposite material. The morphology of the nanocomposite obtained consisted of TiO₂ particles with a size of ∼100 nm, uniformly distributed on the reduced graphene oxide nanosheets. The as-prepared TiO₂–graphene nanocomposite was able to deliver a capacity of 250 mA h g⁻¹ ± 5% at 0.2C for more than 200 cycles with remarkably stable cycle life during the Li⁺ insertion/extraction process. In terms of high rate capability performance, the nanocomposite delivered discharge capacity of ca. 100 mA h g⁻¹ with >99% coulombic efficiency at C-rates of up to 20C. The enhanced electrochemical performance of the material in terms of high rate capability and cycling stability indicates that the as-developed TiO₂–rGO nanocomposites are promising electrode materials for future Li-ion batteries.

A rapid microwave hydrothermal process is adopted for the synthesis of titanium dioxide and reduced graphene oxide nanocomposites as high-performance anode materials for Li-ion batteries.     

UCN–SiO2–GO: a core shell and conjugate system for controlling delivery of doxorubicin by 980 nm NIR pulse

Herein, graphene oxide (GO) has been attached with core–shell upconversion-silica (UCN–SiO₂) nanoparticles (NPs) to form a GO–UCN–SiO₂ hybrid nanocomposite and used for controlled drug delivery. The formation of the nanocomposite has been confirmed by various characterization techniques. To date, a number of reports are available on GO and its drug delivery applications, however, the synergic properties that arise due to the combination of GO, UCNPs and SiO₂ can be used for controlled drug delivery. New composite UCN@SiO₂–GO has been synthesized through a bio-conjugation approach and used for drug delivery applications to counter the lack of quantum efficiency of the upconversion process and control sustained release. A model anticancer drug (doxorubicin, DOX) has been loaded to UCNPs, UCN@SiO₂ NPs and the UCN@SiO₂–GO nanocomposite. The photosensitive release of DOX from the UCN@SiO₂–GO nanocomposite has been studied with 980 nm NIR laser excitation and the results obtained for UCNPs and UCN@SiO₂ NPs compared. It is revealed that the increase in the NIR laser irradiation time from 1 s to 30 s leads to an increase in the amount of DOX release in a controlled manner. In vitro studies using model cancer cell lines have been performed to check the effectiveness of our materials for controlled drug delivery and therapeutic applications. Obtained results showed that the designed UCN@SiO₂–GO nanocomposite can be used for controlled delivery based therapeutic applications and for cancer treatment.

A GO–UCN–SiO₂ hybrid nanocomposite for loading of doxorubicin and its use in in vitro efficiency for killing carcinoma cells.     

Facile solvothermal preparation of Fe3O4–Ag nanocomposite with excellent catalytic performance

Functional nanocomposites demonstrate excellent comprehensive properties and outstanding characteristics for numerous applications. Magnetic nanocomposites are an important type of composite materials, due to their applications in optics, medicine and catalysis. In this report, a new Fe₃O₄-loaded silver (Fe₃O₄–Ag) nanocomposite has been successfully synthesized via a simple solvothermal method and in situ growth of silver nanowires. The silver nanowires were prepared via the reduction of silver vanadate with the addition of uniformly dispersed Fe₃O₄ nanoparticles. Structural and morphological characterizations of the obtained Fe₃O₄–Ag nanocomposite were carried out using many characterization methods. As a new composite catalyst, the synthesized magnetic Fe₃O₄–Ag nanocomposite displayed a high utilization rate of catalytically active sites in catalytic reaction medium and showed good separation and recovery using an external magnetic field. The facile preparation and good catalytic performance of this Fe₃O₄–Ag nanocomposite material demonstrate its potential applications in catalytic treatment and composite materials.

A new Fe₃O₄–Ag nanocomposite was prepared via solvothermal method, demonstrating potential application in catalytic degradation of wastewater treatment and composite materials.     

Estimating the dielectric constant of BaTiO3–polymer nanocomposites by a developed Paletto model

Polymer-based nanocomposites with high dielectric constant have attracted the attention of many researchers, owing to their wide applications in advanced electronics. The experimental measurement of dielectric constant for every polymer-based nanocomposite system is not practically feasible, due to there being many polymer matrixes and nanofiller combinations. Therefore, there is rising interest in predicting the dielectric constant of polymer nanocomposites, using mathematical methods. In this study, we estimate the dielectric constant of polymer nanocomposites by considering astounding interphase properties. The Paletto model is modified, in order to predict the dielectric constant of a BaTiO₃–polymer nanocomposite by properly assuming the interphase parameters, including the thickness of the interphase layer and the dielectric constant of the interphase region. Results from the modified Paletto model are verified by experimental data, indicating that the predicted values agree well with the experimentally determined dielectric constant, and thus the accuracy of the developed model. In addition, the particle concentration will significantly be underestimated if the influence of the interphase volume is ignored. Furthermore, the effects of different parameters, including the dielectric constant of polymer substrate, dielectric constant of particles, particle content, particle size, the thickness of the interphase layer as well as the dielectric constant of the interphase region on the dielectric constant of a BaTiO₃–polymer nanocomposite are also investigated. The developed model provides a useful tool for predicting the dielectric constant of a BaTiO₃–polymer nanocomposite, accompanied by interphase analysis.

A developed model for estimating the dielectric permittivity of BaTiO₃–polymer nanocomposites is proposed by considering the influence of the interphase.     

Enhanced electrochemical performance of MoS2/graphene nanosheet nanocomposites

Molybdenum disulfide (MoS₂) is attractive as an anode material for next-generation batteries, because of its layered structure being favorable for the insertion/deinsertion of Li⁺ ions, and its fairly high theoretical capacity. However, since the MoS₂ anode material has exhibited disadvantages, such as low electrical conductivity and poor cycling stability, to improve the electrochemical performance of MoS₂ in this study, a nanocomposite structure consisting of MoS₂ and GNS (MoS₂/GNS) as an anode for LIBs was prepared, by controlling the weight ratios of MoS₂/GNS. The X-ray diffraction patterns and electron microscopic analysis showed that the nanocomposite electrode structure consisted of well-formed MoS₂ nanoparticles and GNS. Compared to MoS₂-only, the MoS₂/GNS composites exhibited high retention and improved capacity at high current densities. In particular, among these nanocomposite samples, MoS₂/GNS(8 : 2) with an appropriate portion of GNS exhibited the best LIB performance, due to the lowest interfacial resistance and highest Li-ion diffusivity.

MoS₂/GNS 8 : 2 with an appropriate portion of GNS exhibited the best LIB performance, due to the lowest interfacial resistance and highest Li-ion diffusivity.     

Constructing ZIF-8 derived C–ZnS/ZnMoO4@MoS2 and C–ZnS/MoS2 nanocomposites using a simple one-pot strategy to enhance photocatalytic degradation activity

Efficient C–ZnS/ZnMoO₄@MoS₂ and C–ZnS/MoS₂ nanocomposite photocatalysts, using ZIF-8 derived C–ZnO as a precursor were successfully synthesized using a simple one-pot procedure. This is the first application that involves transforming ZIF-8 into C–ZnMoO₄ for photocatalysis. The C–ZnS/ZnMoO₄@MoS₂ and C–ZnS/MoS₂ heterostructures were characterized by X-ray diffraction, UV-vis, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, photocurrent measurements, scanning electron microscopy and transmission electron microscopy. The ZM2 sample of C–ZnS/ZnMoO₄@MoS₂ exhibited enhanced photocatalytic activity of about 2.9 times as high as that of ZIF-8 derived C–ZnO in the reduction of tetracycline hydrochloride, and also showed obvious photocatalytic activity 1.81 and 3.33 times as high as that of a ZM3 sample of C–ZnS/MoS₂ and ZIF-8 derived C–ZnO in the degradation of RhB, respectively. The improved photodegradation activity is a result of the heterogenous structure and the tighter contact between C–ZnS and C–ZnMoO₄ compared with the physical contact of general heterogenous photocatalysts. The C–ZnS/ZnMoO₄@MoS₂ heterostructure photocatalyst is expected to be a new type of nanomaterial for the degradation of pollutants from wastewater.

C-doped ZnS/ZnMoO₄@MoS₂ and ZnS/MoS₂ were prepared using ZIF-8 as a precursor; a simple one-pot strategy was adopted to produce the catalysts with tighter contact.     

A review of molybdenum disulfide (MoS2) based photodetectors: from ultra-broadband,self-powered to flexible devices

Two-dimensional transition metal dichalcogenides (2D TMDs) have attracted much attention in the field of optoelectronics due to their tunable bandgaps, strong interaction with light and tremendous capability for developing diverse van der Waals heterostructures (vdWHs) with other materials. Molybdenum disulfide (MoS₂) atomic layers which exhibit high carrier mobility and optical transparency are very suitable for developing ultra-broadband photodetectors to be used from surveillance and healthcare to optical communication. This review provides a brief introduction to TMD-based photodetectors, exclusively focused on MoS₂-based photodetectors. The current research advances show that the photoresponse of atomic layered MoS₂ can be significantly improved by boosting its charge carrier mobility and incident light absorption via forming MoS₂ based plasmonic nanostructures, halide perovskites–MoS₂ heterostructures, 2D–0D MoS₂/quantum dots (QDs) and 2D–2D MoS₂ hybrid vdWHs, chemical doping, and surface functionalization of MoS₂ atomic layers. By utilizing these different integration strategies, MoS₂ hybrid heterostructure-based photodetectors exhibited remarkably high photoresponsivity raging from mA W⁻¹ up to 10¹⁰ A W⁻¹, detectivity from 10⁷ to 10¹⁵ Jones and a photoresponse time from seconds (s) to nanoseconds (10⁻⁹ s), varying by several orders of magnitude from deep-ultraviolet (DUV) to the long-wavelength infrared (LWIR) region. The flexible photodetectors developed from MoS₂-based hybrid heterostructures with graphene, carbon nanotubes (CNTs), TMDs, and ZnO are also discussed. In addition, strain-induced and self-powered MoS₂ based photodetectors have also been summarized. The factors affecting the figure of merit of a very wide range of MoS₂-based photodetectors have been analyzed in terms of their photoresponsivity, detectivity, response speed, and quantum efficiency along with their measurement wavelengths and incident laser power densities. Conclusions and the future direction are also outlined on the development of MoS₂ and other 2D TMD-based photodetectors.

Two-dimensional transition metal dichalcogenides have attracted much attention in the field of optoelectronics due to their tunable bandgaps, strong interaction with light and tremendous capability for developing diverse van der Waals heterostructures with other nanomaterials.     

Very fast hot carrier diffusion in unconstrained MoS2 on a glass substrate: discovered by picosecond ET-Raman

The currently reported optical-phonon-scattering-limited carrier mobility of MoS₂ is up to 417 cm² V⁻¹ s⁻¹ with two-side dielectric screening: one normal-κ side and one high-κ side. Herein, using picosecond energy transport state-resolved Raman (ET-Raman), we demonstrated very fast hot carrier diffusion in μm-scale (lateral) unconstrained MoS₂ (1.8–18 nm thick) on a glass substrate; this method enables only one-side normal-κ dielectric screening. The ET-Raman method directly probes the diffusion of the hot carrier and its contribution to phonon transfer without contact and additional sample preparation and provides unprecedented insight into the intrinsic D of MoS₂. The measured D values span from 0.76 to 9.7 cm² s⁻¹. A nonmonotonic thickness-dependent D trend is discovered, and it peaks at 3.0 nm thickness. This is explained by the competition between two physical phenomena: with an increase in sample thickness, the increased screening of the substrate results in higher mobility; moreover, thicker samples are subject to more surface contamination, loose substrate contact and weaker substrate dielectric screening. The corresponding carrier mobility varies from 31.0 to 388.5 cm² V⁻¹ s⁻¹. This mobility is surprisingly high considering the normal-κ and single side dielectric screening by the glass substrate. This is a direct result of the less-damaged structure of MoS₂ that is superior to those of MoS₂ samples reported in literature studies that are subjected to various post-processing techniques to facilitate measurement. The very high hot carrier mobility reduces the local carrier concentration and enhances the Raman signal, which is further confirmed by our Raman signal studies and comparison with theoretical studies.

Very high nonmonotonic thickness-dependent hot carrier diffusivity of MoS₂ in a normal-κ dielectric screening environment was discovered by ET-Raman technique.