Electrosyntheses of freestanding polyindole films in boron trifluoride diethyl etherate

High‐quality freestanding polyindole (PIn) films were synthesized electrochemically through the direct oxidation of indole in pure boron trifluoride diethyl etherate (BFEE). The oxidation potential of indole in this medium was measured to be only 0.86 V versus a saturated calomel electrode, which was lower than that determined in acetonitrile/0.1 mol L^?1 Bu₄NBF₄. PIn films obtained from this medium showed better electrochemical behavior and better thermal stability with a conductivity of 10^?1 S cm^?1, and this indicated that BFEE was a better medium than acetonitrile for the electrosyntheses of PIn films. Structural studies showed that the polymerization of indole ring occurred at the 2,3‐position. As‐formed PIn films could be partly dissolved in acetone, acetonitrile, tetrahydrofuran, and so forth. Fluorescent spectral studies indicated that PIn was a good blue‐light emitter. To the best of our knowledge, this is the first report on the fluorescence of PIn. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1444–1453, 2005     

High-performance supercapacitor electrode based on a nanocomposite of polyaniline and chemically exfoliated MoS<Subscript>2</Subscript> nanosheets

In this study, MoS₂ nanosheets were first prepared by exfoliating its bulk material in HCl/LiNO₃ solution with a yield of 45%, and then a facile strategy was developed to synthesize polyaniline/MoS₂ (PANI/MoS₂) nanocomposite via in situ polymerization. Structural and morphological characterizations of MoS₂ nanosheets and the nanocomposite were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray powder diffraction. The results of SEM illustrated that orderly sawtooth polyaniline (PANI) nanoarrays were formed on the surface of MoS₂ nanosheets. The nanocomposite displayed good electrochemical performance as a supercapacitor electrode material. The specific capacitance reached 560 F/g at a current density of 1.0 A g^?1 in 1.0 M H₂SO₄ solution. Such good performance is because that the MoS₂ nanosheets provided a highly electrolytic accessible surface area for redox-active PANI and a direct path for electrons.     

Flexible and environment-friendly regenerated cellulose/MoS2 nanosheet nanogenerators with high piezoelectricity and output performance

Flexible piezoelectric nanogenerators for energy harvesting are getting more and more attention nowadays by converting the mechanical energy to electric energy. Here, an environment-friendly piezoelectric nanogenerator based on the regenerated cellulose (RC)/MoS₂ nanosheet nanocomposite successfully exhibited a relative high output voltage of 2 V and current of 150 nA under slight press which were 5 and 7.5 times higher than those of the neat RC film, i.e. 0.4 V and 20 nA, respectively. In particular, the MoS₂ nanosheets were obtained through a simple, facile and low-cost pathway by mechanical exfoliation in triethanolamine. The nanocomposite film with MoS₂ nanosheets content of 4% exhibited a high piezoelectric constant (d₃₃) of 19 pC/N, which was 6.3 times higher than that of the neat RC film (i.e. 3 pC/N). Thus, the RC/MoS₂ piezoelectric nanogenerator has great potential applications in the fields of energy harvester, sensors and is of great significance to environment protection.

     

Embedding Amorphous Molybdenum Sulfide within a Porous Poly(3,4‐ethylenedioxythiophene) Matrix to Enhance its H2‐evolving Catalytic Activity and Robustness

Amorphous molybdenum sulfide (MoS_x) is a promising alternative to Pt catalyst for the H₂ evolution in water. However, it is suffered of an electrochemical corrosion. In this report, we present a strategy to tack this issue by embedding the MoS_x catalyst within a porous poly(3,4‐ethylenedioxythiophene) (PEDOT) matrix. The PEDOT host is firstly grown onto a fluorine‐doped tin oxide (FTO) electrode by electrochemical polymerization of EDOT monomer in an acetonitrile solution to perform a porous structure. The MoS_x catalyst is subsequently deposited onto the PEDOT by an electrochemical oxidation of [MoS₄]^2? monomer. In a 0.5 M H₂SO₄ electrolyte solution, the MoS_x/PEDOT shows higher H₂‐evolving catalytic activities (current density of 34.2 mA/cm² at ?0.4 V vs RHE) in comparison to a pristine MoS_x grown on a planar FTO electrode having similar catalyst loading (24.2 mA/cm²). The PEDOT matrix contributes to enhance the stability of MoS_x catalyst by a significant manner. As such, the MoS_x/PEDOT retains 81 % of its best catalytic activity after 1000 potential scans from 0 to ?0.4 V vs. RHE, whereas a planar MoS_x catalyst is completely degraded after about 240 potential scans, due to its complete corrosion.     

自支撑柔性聚(5-吲哚硼酸)膜的电化学合成及表征

在三氟化硼乙醚/乙腈的混合体系中,5-吲哚硼酸的电化学氧化可以获得导电率为9×10-4 S·cm-1的自支撑柔性聚(5-吲哚硼酸)膜.5-吲哚硼酸在80％的三氟化硼乙醚亿腈溶液中的起始氧化电位约为0.80V红外光谱确定了5-吲哚硼酸的聚合位点在C2和C3位上.紫外可见光谱测试结果表明聚(5-吲哚硼酸)的能隙约为2.48...     

Antimony anchored in MoS2 nanosheets with N-doped carbon coating to boost potassium storage performance

Potassium ions batteries (PIBs) have been considered as promising energy storage systems owning to potassium rich natural abundances. However, the difficult reaction kinetics and poor cycling of electrode restrict the further development of PIBs. In this work, antimony anchored in MoS₂ nanosheets with N-doped carbon coating (Sb/MoS₂/NCs) are prepared and evaluated as anode for PIBs. In the unique Sb/MoS₂/NCs structure, the volume expansion of Sb particles could be effectively buffered by the around MoS₂ structure. The defects in MoS₂ nanosheets provide more electrochemical reaction sites for sufficient K⁺ insertion/extraction. Furthermore, the N-doped carbon can further accommodate the volume expansion and improve the electronic conductivity of Sb/MoS₂/NCs composites. Due to the above advantages, the Sb/MoS₂/NCs anode delivers a capacity of 235 mAh/g at 50 mA/g after 78 cycles. This work provides a prospective strategy to design advanced anode materials for PIBs using MoS₂ and antimony composites.     

Direct electrochemistry of glucose oxidase and a biosensor for glucose based on a glass carbon electrode modified with MoS2 nanosheets decorated with gold nanoparticles

An electrochemical glucose biosensor was developed by immobilizing glucose oxidase (GOx) on a glass carbon electrode that was modified with molybdenum disulfide (MoS₂) nanosheets that were decorated with gold nanoparticles (AuNPs). The electrochemical performance of the modified electrode was investigated by cyclic voltammetry, and it is found that use of the AuNPs-decorated MoS₂ nanocomposite accelerates the electron transfer from electrode to the immobilized enzyme. This enables the direct electrochemistry of GOx without any electron mediator. The synergistic effect the MoS₂ nanosheets and the AuNPs result in excellent electrocatalytic activity. Glucose can be detected in the concentration range from 10 to 300 μM, and down to levels as low as 2.8 μM. The biosensor also displays good reproducibility and long-term stability, suggesting that it represents a promising tool for biological assays. Figure

A MoS₂-based glucose sensor has been prepared by gold nanoparticles-decorated MoS₂ nanocomposite, which exhibited excellent electrocatalytic activity, reproducibility and long-term stability. It was applied to determine glucose concentration in human serum, suggest the sensor maybe promising for practical application.     

Ultrathin MoS2 Nanosheets Supported on N‐doped Carbon Nanoboxes with Enhanced Lithium Storage and Electrocatalytic Properties

Molybdenum disulfide (MoS₂) has received considerable interest for electrochemical energy storage and conversion. In this work, we have designed and synthesized a unique hybrid hollow structure by growing ultrathin MoS₂ nanosheets on N‐doped carbon shells (denoted as C@MoS₂ nanoboxes). The N‐doped carbon shells can greatly improve the conductivity of the hybrid structure and effectively prevent the aggregation of MoS₂ nanosheets. The ultrathin MoS₂ nanosheets could provide more active sites for electrochemical reactions. When evaluated as an anode material for lithium‐ion batteries, these C@MoS₂ nanoboxes show high specific capacity of around 1000 mAh g^?1, excellent cycling stability up to 200 cycles, and superior rate performance. Moreover, they also show enhanced electrocatalytic activity for the electrochemical hydrogen evolution.     

Highly Sensitive and Selective Determination of Dopamine in the Presence of Ascorbic Acid Using Gold Nanoparticles‐Decorated MoS2 Nanosheets Modified Electrode

Herein, a novel nanocomposite has been synthesized by molybdenum disulfide (MoS₂) nanosheets and gold nanoparticles (AuNPs) via a microwave‐assisted hydrothermal method, which possesses the specific features of both MoS₂ and AuNPs. The AuNPs@MoS₂ nanocomposite modified electrode exhibits excellent electrocatalytic activity toward dopamine (DA). Its oxidation peak current shows a linear dependence over the DA concentration in the range from 0.1 to 200 µM, with a detection limit of 80 nM (S/N=3). More importantly, the AuNPs@MoS₂‐based sensor can detect DA in the presence of a large excess of ascorbic acid. The AuNPs@MoS₂‐based sensor shows good sensitivity, reproducibility and selectivity, suggesting that the AuNPs@MoS₂ nanocomposite is a promising candidate in electrochemical sensing and other electrocatalytic applications.     

MoS2 Nanosheets Supported on 3D Graphene Aerogel as a Highly Efficient Catalyst for Hydrogen Evolution

The development of efficient catalysts for electrochemical hydrogen evolution is essential for energy conversion technologies. Molybdenum disulfide (MoS₂) has emerged as a promising electrocatalyst for hydrogen evolution reaction, and its performance greatly depends on its exposed edge sites and conductivity. Layered MoS₂ nanosheets supported on a 3D graphene aerogel network (GA‐MoS₂) exhibit significant catalytic activity in hydrogen evolution. The GA‐MoS₂ composite displays a unique 3D architecture with large active surface areas, leading to high catalytic performance with low overpotential, high current density, and good stability.     

Nanohybrid Comprising Gold Nanoparticles – MoS2 Nanosheets for Electrochemical Sensing of Folic Acid in Serum Samples

Folic acid (FA) deficiency is associated with several clinical conditions such as megaloblastic anemia, neuropsychiatric, and pregnancy-related syndromes, this makes FA an important metabolite to be monitored. We have fabricated an electrochemical biosensor based on gold nanoparticles decorated molybdenum disulfide nanosheets (AuNPs−MoS₂NSs) nanocomposite as a transducer matrix for specific and rapid electrochemical detection of FA. Differential pulse voltammetry (DPV) studies displayed a rapid analytical response of the fabricated AuNPs−MoS₂NSs/GCE sensor probe towards FA in a wide concentration range of 0.001–100 μM with a very low detection limit of 0.72±0.03 nM. The selectivity of the fabricated sensor probe has been examined in the presence of interferents such as dopamine, uric acid, ascorbic acid, glucose, and urea. The clinical potential of the fabricated biosensor was established by monitoring FA in human serum samples. The developed AuNPs−MoS₂NSs/GCE sensor probe showed high reproducibility and stability, indicating its promise for FA detection in clinical settings.     

利用光热电效应收集近红外光能的二硫化钼和热释电高分子纳米复合物

设计合成了一种基于二硫化钼（MoS₂）/热释电聚合物的柔性薄膜光热电纳米发电机（PTENG）。过渡金属硫族化合物作为薄层纳米薄片,可以捕获近红外（NIR）光,并将其转化为热能。同时,热释电聚合物将无机纳米片所收集的热能转化为电能。在近红外辐照下,PTENG可以瞬间产生电压和光电流,且输出长期保持在较高水平。通过光热效应与热释电效应的有效耦合,该体系具有较高的热电转换系数。我们还通过理论模拟分析了MoS₂在聚合物纳米复合材料中的作用。MoS₂的存在显著提高了热释电聚合物薄膜的温度变化率,提高了器件的光电响应。     

Hybrid Fibers Made of Molybdenum Disulfide,Reduced Graphene Oxide,and Multi‐Walled Carbon Nanotubes for Solid‐State,Flexible, Asymmetric Supercapacitors

One of challenges existing in fiber‐based supercapacitors is how to achieve high energy density without compromising their rate stability. Owing to their unique physical, electronic, and electrochemical properties, two‐dimensional (2D) nanomaterials, e.g., molybdenum disulfide (MoS₂) and graphene, have attracted increasing research interest and been utilized as electrode materials in energy‐related applications. Herein, by incorporating MoS₂ and reduced graphene oxide (rGO) nanosheets into a well‐aligned multi‐walled carbon nanotube (MWCNT) sheet followed by twisting, MoS₂‐rGO/MWCNT and rGO/MWCNT fibers are fabricated, which can be used as the anode and cathode, respectively, for solid‐state, flexible, asymmetric supercapacitors. This fiber‐based asymmetric supercapacitor can operate in a wide potential window of 1.4 V with high Coulombic efficiency, good rate and cycling stability, and improved energy density.     

Hybrid Fibers Made of Molybdenum Disulfide,Reduced Graphene Oxide,and Multi‐Walled Carbon Nanotubes for Solid‐State,Flexible, Asymmetric Supercapacitors

One of challenges existing in fiber‐based supercapacitors is how to achieve high energy density without compromising their rate stability. Owing to their unique physical, electronic, and electrochemical properties, two‐dimensional (2D) nanomaterials, e.g., molybdenum disulfide (MoS₂) and graphene, have attracted increasing research interest and been utilized as electrode materials in energy‐related applications. Herein, by incorporating MoS₂ and reduced graphene oxide (rGO) nanosheets into a well‐aligned multi‐walled carbon nanotube (MWCNT) sheet followed by twisting, MoS₂‐rGO/MWCNT and rGO/MWCNT fibers are fabricated, which can be used as the anode and cathode, respectively, for solid‐state, flexible, asymmetric supercapacitors. This fiber‐based asymmetric supercapacitor can operate in a wide potential window of 1.4 V with high Coulombic efficiency, good rate and cycling stability, and improved energy density.     

Preparation of MoS2‐graphene Hybrid Nanosheets and Simultaneously Electrochemical Determination of Levodopa and Uric Acid

MoS₂ nanoflakes were prepared by exfoliating commercial MoS₂ powders with the assistance of ultrasound and graphene foam was synthesized by chemical vapor deposition using nickel foam as the template. MoS₂‐graphene hybrid nanosheets were developed through the combination of MoS₂ nanoflakes and graphene nanosheets by ultrasonic dispersion. The hybrid nanosheets were sprayed onto the ITO coated glass, which acts as an electrode for the simultaneously electrochemical determination of levodopa and uric acid. The MoS₂‐graphene hybrid nanosheets were characterized by scanning electron microscopy, X‐ray diffraction and Raman spectroscopy. The results show that the hybrid nanosheets are composed of MoS₂ and graphene with a sheet‐like morphology. The sensitivity of the electrode for levodopa and uric acid is 0.36 μA μM⁻¹ and 0.39 μA μM⁻¹, respectively. The electrode also shows low limit of detection, good selectivity, reproducibility and stability. And it is potential for use in clinical research.     

Free‐standing and Flexible MoS2/rGO Paper Electrode for Amperometric Detection of Folic Acid

The development of flexible electrodes is of considerable current interest because of the increasing demand for modern electronics, portable medical products, and compact devices. We report a new type of flexible electrochemical sensor fabricated by integrating graphene and MoS₂ nanosheets. A highly flexible and free‐standing conductive MoS₂ nanosheets/reduced graphene oxide (MoS₂/rGO) paper was prepared by a two‐step process: vacuum filtration and chemical reduction treatment. The MoS₂/graphene oxide (MoS₂/GO) paper obtained by a simple filtration method was transformed into MoS₂/rGO paper after a chemical reduction process. The obtained MoS₂/rGO paper was characterized by scanning electron microscopy, X‐ray diffraction spectroscopy, X‐ray photoelectron spectroscopy, Raman spectroscopy, electrochemical impedance spectroscopy. The electrochemical behavior of folic acid (FA) on MoS₂/rGO paper electrode was investigated by cyclic voltammetry and amperometry. Electrochemical experiments indicated that flexible MoS₂/rGO composite paper electrode exhibited excellent electrocatalytic activity toward the FA, which can be attributed to excellent electrical conductivity and high specific surface area of the MoS₂/rGO paper. The resulting biosensor showed highly sensitive amperometric response to FA with a wide linear range.     

Custom-made sulfonated poly (vinylidene fluoride-co-hexafluoropropylene) nanocomposite membranes for vanadium redox flow battery applications

Sulfonated poly (vinylidene fluoride-co-hexafluoropropylene) (SPVDF-co-HFP) based nanocomposite proton exchange membranes (PEM) are fabricated by simple solution casting method using polydopamine coated exfoliated molybdenum disulfide (PDA-MoS₂) nanosheets as an alternative for Nafion® in vanadium redox flow batteries (VRFBs). PDA-MoS₂ is synthesized by the etching of exfoliated MoS₂ nanosheets with dopamine molecule by self-polymerization method. Various characteristic results clearly demonstrated that the incorporated PDA-MoS₂ nanosheets homogeneously distributed into the SPVDF-co-HFP matrix and the presence of NH/NH₂ group electrostatically interacts with SPVDF-co-HFP to form a strong acid-base pair and thus enhances the proton transport via Grotthuss type mechanism. Besides, the improvement in surface hydrophilicity provides the vehicle type conduction also. As a result, SPVDF-co-HFP/PM nanocomposite membranes showed higher proton conductivity in comparison with the pristine membrane. Especially SPVDF-co-HFP/PM-1 membrane demonstrated the excellent proton conductivity of 5.24 × 10⁻³ Scm⁻¹ at 25 °C, lower vanadium-ion permeability of 1.05 × 10⁻⁸ cm²min⁻¹ and highest membrane selectivity of 49.9 × 10⁴ Scm⁻³min. On the other hand, vanadium-ion stability of the membrane increased by adding the PD-MoS₂ content is attributed to their strong electrostatic attraction towards the polymer matrix. Overall results suggested that the SPVDF-co-HFP/PM-1 nanocomposite membrane is found to be a better alternative for commercially costly Nafion in VRFB applications.     

Hydrothermal exfoliated molybdenum disulfide nanosheets as anode material for lithium ion batteries

Ultrathin MoS2nanosheets were prepared in high yield using a facile and effective hydrothermal intercalation and exfoliation route. The products were characterized in detail using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that the high yield of MoS2nanosheets with good quality was successfully achieved and the dimensions of the immense nanosheets reached 1 μm–2 μm. As anode material for Li-ion batteries, the as-prepared MoS2nanosheets electrodes exhibited a good initial capacity of 1190 mAh g-1and excellent cyclic stability at constant current density of 50 mA g-1. After 50 cycles, it still delivered reversibly sustained high capacities of 750 mAh g-1.     

In-situ formation of 2H phase MoS2/cerium-zirconium oxide nanohybrid for potential electrochemical detection of an anticancer drug flutamide

The developing field of sensors is highly motivated and attracted by two-dimensional transition metal dichalcogenides (TMDs) with transition metal oxide integration. Initially, molybdenum disulfide (MoS₂), one among the TMDs with cerium-zirconium oxide (CZO), was one-pot synthesized via hydrothermal method for sensing flutamide (FLD). The as-synthesized hybrid nanocomposite was characterized to understand their physical and chemical presence. MoS₂-CZO was well assigned with crystalline nature observed from X-ray powder diffraction and X-ray photoelectron spectroscopy. High-resolution transmission electron microscopy confirms the irregularly arranged nanoparticles wrapped with MoS₂ sheets. The wide surface area with more electroactive sites has provided higher conductance of the MoS₂-CZO/glassy carbon electrode. The limit of detection was 0.005 μM with a linear range of 0.019 μM to 668.5 μM, sensitivity 0.353 μA μM?1 cm^?2. The practical feasibility was analyzed with human urine and river water samples, whereas the obtained results showed excellent FLD detection. The fabricated MoS₂-CZO with all these distinguished analyses will be an outbreak in the field of electrochemical sensors.     

Thermochemical and Electrochemical Stability of Electrolyte Systems based on Sulfolane

UV spectroscopy and cyclic voltammetry were used to examine the thermochemical and electrochemical stabilities of liquid sulfolane-based electrolyte systems for lithium and lithium-ion batteries. It was found that solutions of lithium salts in sulfolane are stable in prolonged keeping at 100°C. The thermochemical stability of lithium salt solutions in sulfolane changes in the order LiBF₄ > LiClO₄ ≈ LiN(CF₃SO₂)₂ > LiCF₃SO₃. It was shown that the electrochemical stability of lithium salt solutions in sulfolane is in the range from 5.5 to 5.9 V (relative to Li/Li⁺) and prolonged action of high temperatures (100°C) does not yield electrochemically active thermal destruction products.