Exfoliated tungsten disulfide-polypyrrole nanocomposites

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Dahn This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4769189/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 07 Oct, 2024 Read the published version in Journal of Inorganic and Organometallic Polymers and Materials → Version 1 posted 11 You are reading this latest preprint version Abstract Exfoliated tungsten disulfide-polypyrrole nanocomposites were synthesized via an in-situ polymerization method and characterized by techniques such as powder X-ray diffraction, thermogravimetric analysis, Seebeck coefficient, and electronic conductivity measurements. The electronic conductivity was found to decrease as the mass % of tungsten disulfide (WS 2 ) in the nanocomposites was increased. The Seebeck coefficients on the synthesized materials were small and positive, suggesting that the bulk polypyrrole and synthesized nanocomposites were p-type conductors. Addition of WS 2 to the polypyrrole showed no changes in thermal stability. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction Hybrid materials consisting of organic and inorganic polymeric materials continue to attract a considerable amount of interest in the scientific community [ 1 ]. These materials have been referred to as nanocomposites since the two components are intimately mixed at the molecular level [ 2 ]. In principle enhanced properties such as electronic [ 3 ], ionic conductivity [ 4 ], thermal [ 5 ] and mechanical [ 6 ] can be obtained from these nanocomposites that cannot be obtained by the components all by themselves. The polymeric material in these nanocomposites ranges from saturated polymers such as polyethylene [ 7 ] and polyethylene glycol [ 8 ] to conjugated polymers such as polystyrene [ 9 ] and conductive polythiophene [ 10 ]. On the other hand, the inorganic component can be three dimensional materials such as metal organic frameworks [ 11 ] and zeolitic phases [ 12 ], two dimensional layered structures such as transition metal oxides [ 13 ] and sulfides [ 14 ] as well as one dimensional systems, e.g. polymeric chains based on hollow carbon nanoparticle chains [ 15 ]. With regards to nanocomposite materials based on layered systems, there are two systems that can be synthesized namely, intercalated and exfoliated [ 16 ]. The motivation for working on these materials is enormous as these have found applications in many fields, including catalysis [ 17 ], corrosion protection [ 18 ], construction [ 19 ] and battery systems [ 20 ]. Recent focus has been on nanocomposites formed from electronically conducting polymers and transition metal dichalcogenides (TMDs) [ 21 ]. TMDs are a class of graphene-analogous materials, formed from layers of covalently bonded atoms with weaker intermolecular van der Waals interactions between the layers. TMDs have the general formula of MX 2 , where M is a transition metal (e.g., tungsten) and X is a chalcogen (e.g., sulfur). Some TMDs act as electronic semiconductors; such is the case for bulk WS 2 in its most common 2H form [ 22 ]. Electronically conducting polymers have attracted attention for their use in devices such as supercapacitors, electrochromic, biosensors, and electrocatalysts [ 23 ]. While many conducting polymers have been synthesized, polyaniline (PANI), polythiophene (PTh), and polypyrrole (PPy) have been the focus of research due to their high electronic conductivity, environmental stability, and ease of synthesis [ 16 ]. Despite their environmental stability, these conducting polymers lack durability and have a low capacitance. To rectify these issues, nanocomposites of conducting polymers with TMDs have been synthesized. Nanocomposites are often more mechanically durable and have greater specific capacitance [ 16 ]. In the past, intercalated nanocomposites of WS 2 and conducting polymers have been the subject of research [ 16 ]. More recently, a method was developed to synthesize WS 2 in an exfoliated state without the use of the dangerously reactive n-BuLi; this method involves a solid-state reaction between powdered tungstic acid and excess thiourea under an inert atmosphere and at a high temperature [ 24 ]. We have capitalized on this procedure to prepare exfoliated nanocomposites consisting of polypyrrole (PPy) and WS 2 at various mass %. We found that addition of deionized water to the exfoliated WS 2 followed by probe sonication completely dispersed the dichalcogenide into a colloidal suspension. Mixing the suspension with a solution of pyrrole in I M HCl followed by the addition of an acidified solution of ammonium persulfate resulted in the formation of exfoliated WS 2 -PPy nanocomposites. The nanocomposites were characterized by powder X-ray diffraction, thermogravimetric analysis, ATR-FTIR, conductivity, and thermopower measurements. 2. Materials Pyrrole and tungstic acid were purchased from Sigma-Aldrich and were used without further purification. Ammonium persulfate, thiourea, and hydrochloric acid were obtained from Fisher and were also used without further purification. 3. Instrumentation Powder X-ray diffraction was performed using a Bruker AXS D8 Advance instrument equipped with a graphite monochromator, variable divergence slit, variable anti-scatter slit, and scintillation detector. Cu (Kα) radiation (λ = 1.524 Å) was used for sample measurements. All measurements were performed from 2˚ to 60˚ (2Θ) in air and at room temperature. Thermogravimetric analysis (TGA) was performed on a TGA Q500 TA Instruments. The nitrogen flow over the balance was kept at 40 mL/min, while dry air or nitrogen flow over the sample was maintained at 60 mL/min. For TGA performed under nitrogen, the furnace was purged for 20 minutes using a 60 mL/min nitrogen flow rate before measurements began. The heating rate was kept at 10 ˚C/min for all measurements. The range of heating was from room temperature to 700 ˚C. ATR-FTIR was performed using the ATR attachment for a Bruker Equinox 55 series spectrometer over a range of 4000 − 400 cm − 1 . The resolution of the equipment was 0.9 cm − 1 . Samples were tested in their powdered form except for pyrrole, which was in the liquid phase. 64 scans were performed to collect the spectra. Circular pellets for conductivity measurements were 13.1 mm in diameter, with a thickness between 0.2 mm and 0.9 mm. These pellets were pressed with a pressure of about 1500 psi for one minute. Four-probe van der Pauw conductivity measurements were performed on the samples in air, using a home-built system. For some samples, variable temperature conductivity measurements were carried out under vacuum. Thermopower (Seebeck coefficient) measurements were also run on the pressed pellets using a home-built apparatus similar to the one described by Hitchcock et al. [ 25 ]. The pellet being tested was sandwiched between two copper block electrodes. One of these electrodes was heated to create a temperature difference; this difference was measured using a thermocouple. As the temperature difference increased, a voltage was generated; this was measured as a function of temperature to determine the thermopower of the pressed pellets. The thermopower of copper (+ 1.8 µV/K) was then added, to give the absolute thermopower of the sample. 4. Experimental section Synthesis of exfoliated tungsten disulfide The synthetic procedure was adapted from the method described by Matte et al. [ 24 ]. Tungstic acid and an excess of thiourea were ground together with a mortar and pestle. This mixture was placed in a ceramic boat which was then installed in a ceramic tube. The ceramic tube containing the ceramic boat was then placed in a split furnace, which was purged with nitrogen at a gentle rate for 20 minutes. The temperature of the furnace was then slowly raised to 500 ˚C, under nitrogen purge. The furnace was kept at 500 ˚C for about three hours with a constant nitrogen flow. Once the three hours had elapsed, the furnace was turned off and the contents were left in to cool under nitrogen overnight. A dark product was then collected. A mortar and pestle were used to grind the product into a fine powder for characterization and for use in subsequent nanocomposite preparations. Synthesis of tungsten-disulfide polypyrrole nanocomposites An amount of exfoliated WS 2 was placed in 20 mL of deionized water and probe sonicated at 30% amplitude for 20 minutes using a Celo-Parmer 750 W ultrasonic processor. The aqueous suspension of WS 2 was then added to a solution of pyrrole in 1M HCl that was magnetically stirred at ice temperature. A solution of ammonium persulfate in 1M HCl that was previously cooled in an ice bath was then added dropwise to the reaction vessel. The reaction mixture was stirred at ice temperature for 2.5 hours. The product was vacuum filtered, washed with 125 mL of 1 M HCl, and dried on the filter overnight. The next day, a black product was collected. A mortar and pestle were used to break apart the aggregated material for characterization. The amount of exfoliated WS 2 in the mixture was tailored to produce the desired mass ratio of WS 2 to polypyrrole in the final product. Nanocomposites with the following WS 2 content were synthesized: 1%, 2%, 10%, 20%, 30%, 40%, and 50% WS 2 by mass. Bulk PPy was synthesized following the same procedure but with the omission of WS 2 . 5. Results and Discussion Powder X-ray diffraction The diffractogram of the synthesized WS 2 showed distinct peaks at 33˚ (2Θ) and 58˚ (2Θ), characteristic of exfoliated WS 2 ; the absence of a strong (002) peak confirmed that the synthesized WS 2 was amorphous and is indeed in an exfoliated state. [ 26 ] Bulk PPy was also characterized using XRD. The broad peak observed in the range of 15˚<2Θ < 30˚ confirmed that the PPy was in an amorphous state and is consistent with the literature [ 27 ]. The powder patterns for the nanocomposites bore a strong resemblance to that of bulk PPy; the same broad peak in the range 15˚<2Θ < 30˚ was observed in the diffractograms of the nanocomposites. As the WS 2 content in the nanocomposites was increased, the diffractograms became increasingly similar to that of the synthesized WS 2 . A peak emerged at approximately 33˚(2Θ) in the powder pattern of the nanocomposite that contained 20% WS 2 and became more prominent in the patterns of the nanocomposites consisting of 30%, 40%, and 50% WS 2 . Another peak near 58˚ (2Θ) was also observed in the nanocomposite containing 50% WS 2 . Room-Temperature Conductivity Measurements Room-temperature conductivity measurements were performed at 290 K in air and are shown in Fig. 2 . Error bars indicate the estimated uncertainty of each measurement. There are three data points at 40%: measurements on two pellets from one synthesis and one pellet from a different synthesis. There is good agreement among these three. The conductivity of polypyrrole was found to be 11.7 ± 1.2 S/cm. This value is high and is close to the value of 10 S/cm reported in the literature where a mole ratio of 4:1 of FeCl 3 to the monomer was used [ 28 ]. For the nanocomposites, the general trend was that the conductivity decreased with increasing WS 2 content. The lower conductivity of the 30% sample is not clear. This could be attributed to several factors such as significant difference in the amount of humidity during the synthesis, relatively longer time between the synthesis and conductivity measurements, and a lower pressure used for pressing the pellet. The synthesized exfoliated WS 2 had a conductivity too small to be measured with our system. Bulk 2H-WS 2 is a semiconductor whose conductivity would have been measurable. The fact that the pellets of synthesized exfoliated WS 2 appeared to be insulators could be due to thiourea residue coating the surface of the exfoliated WS 2 . The ATR-FTIR spectrum for the synthesized exfoliated WS 2 exhibited peaks at 1395 cm − 1 , 1230 cm − 1 , and 804 cm − 1 , and these were attributed to decomposed thiourea on the surface of the exfoliated WS 2 . In fact, thiourea decomposition has been shown to begin at 140°C [ 29 ], well below the synthesis temperature of 500°C used for the exfoliated WS 2 . To remove the decomposed thiourea, a sample of the synthesized WS 2 was heated to 200°C under a dry air purge. ATR-FTIR spectra showed little change after 149 minutes of heating. It was concluded that the decomposed thiourea was strongly attached to the exfoliated WS 2 , possibly through covalent bonds to sulfur or dative bonds to the tungsten atoms within the layers. Higher temperatures during the cleaning or an alteration in the ratio of tungstic acid to thiourea during the synthesis could reduce contamination from decomposed thiourea. Variable-Temperature Conductivity Measurements Following room-temperature measurements in air, variable-temperature conductivity measurements were performed on some of the pellets. These were done in vacuum, and the samples were kept in the vacuum chamber for at least 12 hours before measurement. At room temperature (about 290 K), the conductivity of all the synthesized materials was lower (by 8–20%) under vacuum than under atmospheric conditions. As seen in Fig. 3 , PPy and the nanocomposites showed a positive correlation between temperature and conductivity. The relationship is nearly linear, very different from the exponential behavior typical of semiconductors. The temperature dependence of conductivity can be fit to an inhomogeneous conduction model [ 30 ], which assumes there is good conduction in some regions of the material, and that these highly conducting regions are separated by poorly conducting disordered regions through which mobile charges travel by a hopping process. When hopping is the dominant effect limiting current flow, as it is in many conducting polymers and related nanocomposites, the model is equivalent to the variable-range hopping (VRH or Mott law) model [ 31 ]. In this model, the resistivity ρ and conductivity σ are given by: \(\:\rho\:={\sigma\:}^{-1}={f}_{n}{\rho\:}_{0}{exp}\left[{\left(\frac{{T}_{0}}{T}\right)}^{\gamma\:}\right]\) , [ 1 ] where T is the absolute temperature, and the other parameters are constants. In three dimensions, γ is expected to be 0.25. VRH-like conductivity with γ ≈ 0.25 has been reported in, for example, other polypyrrole/MoS 2 nanocomposites [ 32 ] and polyaniline/FeOCl nanocomposites [ 33 ]. When equation [ 1 ] is valid, a graph of the logarithm of ρ as a function of T − 0.25 will be a straight line. Such a plot is shown in Fig. 4 and demonstrates that the data are consistent with VRH conductivity. The conductivity results suggest that charge transport in these materials proceeds mainly through the PPy fraction of the nanocomposites. Adding poorly conducting exfoliated WS 2 introduces additional barriers to the flow of charge and reduces the overall conductivity. Seebeck Coefficient Seebeck coefficients for all synthesized materials are shown in Fig. 5 . Error bars indicate the standard deviation of several measurements at each composition. All were small and positive, suggesting that the bulk PPy and synthesized composites were p-type conductors. The values for the Seebeck coefficients generally increased alongside the WS 2 content of the composites. As shown in the conductivity measurements, the synthesized exfoliated WS 2 was an insulator (2H phase), which made it impossible to measure its Seebeck coefficient. This is consistent with the literature where the Seebeck coefficient of WS 2 nanosheets in 2H phase could not be measured, but in the IT phase the nanosheets displayed a Seebeck coefficient of 30 µV K –1 [ 34 ]. Thermogravimetric analysis Thermograms obtained under air purge (Fig. 6 ) showed that increasing WS 2 content in the composites had minimal effect on thermal properties other than an increase in mass remaining at 700°C. The exception to this was the 1% WS 2 /PPy sample, which showed marginally lower mass at the end of the TGA run; this was attributed to random errors, as the difference was less than 1% of the initial starting mass for each (1.65% remaining mass in 1% composite versus 2.55% in the PPy sample). Data acquired under nitrogen purge (Fig. 7 ) showed a different trend. Samples that contained 10% and 20% WS 2 by weight lost less mass across the entire heating range compared to the exfoliated WS 2 on its own. Excluding the 1% WS 2 /PPy sample, composites up to 40% WS 2 by weight maintained mass up to 700°C better than the WS 2 all by itself. This effect was not observed in the 50% WS 2 /PPy sample. All composite samples and PPy lost mass over a wider range of temperatures compared to the abrupt loss observed in the WS 2 . Conclusions XRD confirmed that the synthesized WS 2 and composites were in the exfoliated state. FTIR showed that the synthesized WS 2 had been coated with thiourea residue that could not be removed with additional heating. It was shown with TGA that the addition of WS 2 did not alter the thermal stability of PPy, a trend consistent throughout all tested composites. Variable-temperature conductivity measurements showed that the electrical conductivity of the synthesized composites increased with temperature, in a way consistent with a variable-range hopping model. 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Cite Share Download PDF Status: Published Journal Publication published 07 Oct, 2024 Read the published version in Journal of Inorganic and Organometallic Polymers and Materials → Version 1 posted Editorial decision: Revision requested 15 Aug, 2024 Reviews received at journal 15 Aug, 2024 Reviewers agreed at journal 13 Aug, 2024 Reviews received at journal 12 Aug, 2024 Reviewers agreed at journal 10 Aug, 2024 Reviewers agreed at journal 09 Aug, 2024 Reviewers agreed at journal 09 Aug, 2024 Reviewers invited by journal 08 Aug, 2024 Editor assigned by journal 24 Jul, 2024 Submission checks completed at journal 24 Jul, 2024 First submitted to journal 19 Jul, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4769189","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":340819752,"identity":"1b333fe9-2356-4dfb-817e-8b6ba62817ab","order_by":0,"name":"Michael Kozma","email":"","orcid":"","institution":"University of Prince Edward Island","correspondingAuthor":false,"prefix":"","firstName":"Michael","middleName":"","lastName":"Kozma","suffix":""},{"id":340819753,"identity":"3bcba598-f227-4d64-a590-96b40290392d","order_by":1,"name":"Rabin Bissessur","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA20lEQVRIiWNgGAWjYFACHoYDUBbjAzCXFC3MBkRrgQE2CaKcZd5+9uDBH39s7OVn5D6r5t1hI8PAfvgBXi0yZ/ISDvO2pSVuuJFudpv3TBoPA0+aAV4tEgw5BocZGw4nGEiksd3mbTvMAxQioIX/jQHQYf+BDktjK+Zt+w/Uwv4BvxaJHIMDPGwHGBtupLEx87YdAGrhIWCLxDuQX5ITN5x5xiw590wyDxtPTgEBh+Ue/vjjj529fHsa44e3O+zs+dmPb8CrBRUwNgBjhwT1UC2jYBSMglEwCtABAHfdQGbX+21pAAAAAElFTkSuQmCC","orcid":"","institution":"University of Prince Edward Island","correspondingAuthor":true,"prefix":"","firstName":"Rabin","middleName":"","lastName":"Bissessur","suffix":""},{"id":340819754,"identity":"c0cbf725-c647-4df0-824c-3a4e1df2ea30","order_by":2,"name":"Bowen Gao","email":"","orcid":"","institution":"University of Prince Edward Island","correspondingAuthor":false,"prefix":"","firstName":"Bowen","middleName":"","lastName":"Gao","suffix":""},{"id":340819755,"identity":"19234007-ffaf-4449-b83f-a4c8834add48","order_by":3,"name":"Douglas C. Dahn","email":"","orcid":"","institution":"University of Prince Edward Island","correspondingAuthor":false,"prefix":"","firstName":"Douglas","middleName":"C.","lastName":"Dahn","suffix":""}],"badges":[],"createdAt":"2024-07-19 18:32:20","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4769189/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4769189/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10904-024-03388-7","type":"published","date":"2024-10-07T15:56:49+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":62887576,"identity":"8515c4d7-43e8-439b-8cce-bb27330d1f5c","added_by":"auto","created_at":"2024-08-20 16:21:24","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":53783,"visible":true,"origin":"","legend":"\u003cp\u003eDiffractograms from top to bottom: WS\u003csub\u003e2\u003c/sub\u003e, 50% WS\u003csub\u003e2\u003c/sub\u003e/PPy, 40% WS\u003csub\u003e2\u003c/sub\u003e/PPy, 30% WS\u003csub\u003e2\u003c/sub\u003e/PPy, 20% WS\u003csub\u003e2\u003c/sub\u003e/PPy, 10% WS\u003csub\u003e2\u003c/sub\u003e/PPy, 1% WS\u003csub\u003e2\u003c/sub\u003e/PPy, PPy.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4769189/v1/8778ab1ae8702520157d485c.png"},{"id":62887577,"identity":"28f327fa-4d1c-47e8-842e-b71d96a5592e","added_by":"auto","created_at":"2024-08-20 16:21:24","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":16634,"visible":true,"origin":"","legend":"\u003cp\u003eRoom-temperature conductivity of PPy and nanocomposites.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4769189/v1/9fac061f38bf73e72837a733.png"},{"id":62887579,"identity":"53010443-35d7-4811-bdf4-97a4cad2a43c","added_by":"auto","created_at":"2024-08-20 16:21:25","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":52146,"visible":true,"origin":"","legend":"\u003cp\u003eConductivities of nanocomposites and PPy as a function of temperature.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4769189/v1/878b1488b7a92ac35ee0526d.png"},{"id":62887582,"identity":"ba2d088f-a938-4ed4-af25-b8ead6013ab7","added_by":"auto","created_at":"2024-08-20 16:21:25","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":59508,"visible":true,"origin":"","legend":"\u003cp\u003ePlot of ln(ρ) as a function of T\u003csup\u003e-0.25\u003c/sup\u003e indicating that the conductivity of PPy and the nanocomposites is consistent with a three-dimensional variable-range hopping model.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4769189/v1/7d5528e1fa947a11a30f98a0.png"},{"id":62887961,"identity":"93eb204e-0d73-441f-811f-adf5b02deb49","added_by":"auto","created_at":"2024-08-20 16:29:25","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":27031,"visible":true,"origin":"","legend":"\u003cp\u003eSeebeck coefficient versus WS\u003csub\u003e2\u003c/sub\u003e content for PPy and composites.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4769189/v1/198746b51baac6fb15e372d5.png"},{"id":62887960,"identity":"d1573099-6811-4de2-97f8-74e56a6a4360","added_by":"auto","created_at":"2024-08-20 16:29:24","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":30936,"visible":true,"origin":"","legend":"\u003cp\u003eThermograms of (from top to bottom) WS\u003csub\u003e2\u003c/sub\u003e, 40% WS\u003csub\u003e2\u003c/sub\u003e/PPy, 30% WS\u003csub\u003e2\u003c/sub\u003e/PPy, 20% WS\u003csub\u003e2\u003c/sub\u003e/PPy, 10% WS\u003csub\u003e2\u003c/sub\u003e/PPy, PPy, 1% WS\u003csub\u003e2\u003c/sub\u003e/PPy. Thermograms were acquired with an air sample purge.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-4769189/v1/8eb02fc0a2061e08c14e9a2a.png"},{"id":62888430,"identity":"203cc0fc-29e7-4179-8a6a-1b1fc247cc10","added_by":"auto","created_at":"2024-08-20 16:37:24","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":19836,"visible":true,"origin":"","legend":"\u003cp\u003eThermograms of (top to bottom) 20% WS\u003csub\u003e2\u003c/sub\u003e/PPy, 10% WS\u003csub\u003e2\u003c/sub\u003e/PPy, 40% WS\u003csub\u003e2\u003c/sub\u003e/PPy, 30% WS\u003csub\u003e2\u003c/sub\u003e/PPy, WS\u003csub\u003e2\u003c/sub\u003e, 50% WS\u003csub\u003e2\u003c/sub\u003e/PPy, PPy, 1% WS\u003csub\u003e2\u003c/sub\u003e/PPy. Data were acquired under nitrogen purge.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-4769189/v1/b43cbf9f887c48d592140157.png"},{"id":66597021,"identity":"011e24e5-96d1-4a68-a42b-3a6969a948a1","added_by":"auto","created_at":"2024-10-14 16:04:29","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":537027,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4769189/v1/761e117b-ed54-4cc3-8034-73558a634c89.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Exfoliated tungsten disulfide-polypyrrole nanocomposites","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eHybrid materials consisting of organic and inorganic polymeric materials continue to attract a considerable amount of interest in the scientific community [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. These materials have been referred to as nanocomposites since the two components are intimately mixed at the molecular level [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In principle enhanced properties such as electronic [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], ionic conductivity [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], thermal [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] and mechanical [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] can be obtained from these nanocomposites that cannot be obtained by the components all by themselves. The polymeric material in these nanocomposites ranges from saturated polymers such as polyethylene [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] and polyethylene glycol [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] to conjugated polymers such as polystyrene [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] and conductive polythiophene [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. On the other hand, the inorganic component can be three dimensional materials such as metal organic frameworks [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] and zeolitic phases [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], two dimensional layered structures such as transition metal oxides [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] and sulfides [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] as well as one dimensional systems, e.g. polymeric chains based on hollow carbon nanoparticle chains [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWith regards to nanocomposite materials based on layered systems, there are two systems that can be synthesized namely, intercalated and exfoliated [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The motivation for working on these materials is enormous as these have found applications in many fields, including catalysis [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], corrosion protection [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], construction [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] and battery systems [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Recent focus has been on nanocomposites formed from electronically conducting polymers and transition metal dichalcogenides (TMDs) [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. TMDs are a class of graphene-analogous materials, formed from layers of covalently bonded atoms with weaker intermolecular van der Waals interactions between the layers. TMDs have the general formula of MX\u003csub\u003e2\u003c/sub\u003e, where M is a transition metal (e.g., tungsten) and X is a chalcogen (e.g., sulfur). Some TMDs act as electronic semiconductors; such is the case for bulk WS\u003csub\u003e2\u003c/sub\u003e in its most common 2H form [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eElectronically conducting polymers have attracted attention for their use in devices such as supercapacitors, electrochromic, biosensors, and electrocatalysts [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. While many conducting polymers have been synthesized, polyaniline (PANI), polythiophene (PTh), and polypyrrole (PPy) have been the focus of research due to their high electronic conductivity, environmental stability, and ease of synthesis [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Despite their environmental stability, these conducting polymers lack durability and have a low capacitance. To rectify these issues, nanocomposites of conducting polymers with TMDs have been synthesized. Nanocomposites are often more mechanically durable and have greater specific capacitance [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn the past, intercalated nanocomposites of WS\u003csub\u003e2\u003c/sub\u003e and conducting polymers have been the subject of research [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. More recently, a method was developed to synthesize WS\u003csub\u003e2\u003c/sub\u003e in an exfoliated state without the use of the dangerously reactive n-BuLi; this method involves a solid-state reaction between powdered tungstic acid and excess thiourea under an inert atmosphere and at a high temperature [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. We have capitalized on this procedure to prepare exfoliated nanocomposites consisting of polypyrrole (PPy) and WS\u003csub\u003e2\u003c/sub\u003e at various mass %. We found that addition of deionized water to the exfoliated WS\u003csub\u003e2\u003c/sub\u003e followed by probe sonication completely dispersed the dichalcogenide into a colloidal suspension. Mixing the suspension with a solution of pyrrole in I M HCl followed by the addition of an acidified solution of ammonium persulfate resulted in the formation of exfoliated WS\u003csub\u003e2\u003c/sub\u003e-PPy nanocomposites. The nanocomposites were characterized by powder X-ray diffraction, thermogravimetric analysis, ATR-FTIR, conductivity, and thermopower measurements.\u003c/p\u003e"},{"header":"2. Materials","content":"\u003cp\u003ePyrrole and tungstic acid were purchased from Sigma-Aldrich and were used without further purification. Ammonium persulfate, thiourea, and hydrochloric acid were obtained from Fisher and were also used without further purification.\u003c/p\u003e"},{"header":"3. Instrumentation","content":"\u003cp\u003ePowder X-ray diffraction was performed using a Bruker AXS D8 Advance instrument equipped with a graphite monochromator, variable divergence slit, variable anti-scatter slit, and scintillation detector. Cu (Kα) radiation (λ\u0026thinsp;=\u0026thinsp;1.524 \u0026Aring;) was used for sample measurements. All measurements were performed from 2˚ to 60˚ (2Θ) in air and at room temperature.\u003c/p\u003e \u003cp\u003eThermogravimetric analysis (TGA) was performed on a TGA Q500 TA Instruments. The nitrogen flow over the balance was kept at 40 mL/min, while dry air or nitrogen flow over the sample was maintained at 60 mL/min. For TGA performed under nitrogen, the furnace was purged for 20 minutes using a 60 mL/min nitrogen flow rate before measurements began. The heating rate was kept at 10 ˚C/min for all measurements. The range of heating was from room temperature to 700 ˚C.\u003c/p\u003e \u003cp\u003eATR-FTIR was performed using the ATR attachment for a Bruker Equinox 55 series spectrometer over a range of 4000\u0026thinsp;\u0026minus;\u0026thinsp;400 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The resolution of the equipment was 0.9 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Samples were tested in their powdered form except for pyrrole, which was in the liquid phase. 64 scans were performed to collect the spectra.\u003c/p\u003e \u003cp\u003eCircular pellets for conductivity measurements were 13.1 mm in diameter, with a thickness between 0.2 mm and 0.9 mm. These pellets were pressed with a pressure of about 1500 psi for one minute. Four-probe van der Pauw conductivity measurements were performed on the samples in air, using a home-built system. For some samples, variable temperature conductivity measurements were carried out under vacuum.\u003c/p\u003e \u003cp\u003eThermopower (Seebeck coefficient) measurements were also run on the pressed pellets using a home-built apparatus similar to the one described by Hitchcock et al. [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The pellet being tested was sandwiched between two copper block electrodes. One of these electrodes was heated to create a temperature difference; this difference was measured using a thermocouple. As the temperature difference increased, a voltage was generated; this was measured as a function of temperature to determine the thermopower of the pressed pellets. The thermopower of copper (+\u0026thinsp;1.8 \u0026micro;V/K) was then added, to give the absolute thermopower of the sample.\u003c/p\u003e"},{"header":"4. Experimental section","content":"\u003cp\u003e \u003cem\u003eSynthesis of exfoliated tungsten disulfide\u003c/em\u003e \u003c/p\u003e \u003cp\u003eThe synthetic procedure was adapted from the method described by Matte et al. [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Tungstic acid and an excess of thiourea were ground together with a mortar and pestle. This mixture was placed in a ceramic boat which was then installed in a ceramic tube. The ceramic tube containing the ceramic boat was then placed in a split furnace, which was purged with nitrogen at a gentle rate for 20 minutes. The temperature of the furnace was then slowly raised to 500 ˚C, under nitrogen purge. The furnace was kept at 500 ˚C for about three hours with a constant nitrogen flow. Once the three hours had elapsed, the furnace was turned off and the contents were left in to cool under nitrogen overnight. A dark product was then collected. A mortar and pestle were used to grind the product into a fine powder for characterization and for use in subsequent nanocomposite preparations.\u003c/p\u003e \u003cp\u003e \u003cem\u003eSynthesis of tungsten-disulfide polypyrrole nanocomposites\u003c/em\u003e \u003c/p\u003e \u003cp\u003eAn amount of exfoliated WS\u003csub\u003e2\u003c/sub\u003e was placed in 20 mL of deionized water and probe sonicated at 30% amplitude for 20 minutes using a Celo-Parmer 750 W ultrasonic processor. The aqueous suspension of WS\u003csub\u003e2\u003c/sub\u003e was then added to a solution of pyrrole in 1M HCl that was magnetically stirred at ice temperature. A solution of ammonium persulfate in 1M HCl that was previously cooled in an ice bath was then added dropwise to the reaction vessel. The reaction mixture was stirred at ice temperature for 2.5 hours. The product was vacuum filtered, washed with 125 mL of 1 M HCl, and dried on the filter overnight. The next day, a black product was collected. A mortar and pestle were used to break apart the aggregated material for characterization.\u003c/p\u003e \u003cp\u003eThe amount of exfoliated WS\u003csub\u003e2\u003c/sub\u003e in the mixture was tailored to produce the desired mass ratio of WS\u003csub\u003e2\u003c/sub\u003e to polypyrrole in the final product. Nanocomposites with the following WS\u003csub\u003e2\u003c/sub\u003e content were synthesized: 1%, 2%, 10%, 20%, 30%, 40%, and 50% WS\u003csub\u003e2\u003c/sub\u003e by mass. Bulk PPy was synthesized following the same procedure but with the omission of WS\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e"},{"header":"5. Results and Discussion","content":"\u003cp\u003e \u003cem\u003ePowder X-ray diffraction\u003c/em\u003e \u003c/p\u003e \u003cp\u003eThe diffractogram of the synthesized WS\u003csub\u003e2\u003c/sub\u003e showed distinct peaks at 33˚ (2Θ) and 58˚ (2Θ), characteristic of exfoliated WS\u003csub\u003e2\u003c/sub\u003e; the absence of a strong (002) peak confirmed that the synthesized WS\u003csub\u003e2\u003c/sub\u003e was amorphous and is indeed in an exfoliated state. [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eBulk PPy was also characterized using XRD. The broad peak observed in the range of 15˚\u0026lt;2Θ \u0026lt; 30˚ confirmed that the PPy was in an amorphous state and is consistent with the literature [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe powder patterns for the nanocomposites bore a strong resemblance to that of bulk PPy; the same broad peak in the range 15˚\u0026lt;2Θ \u0026lt; 30˚ was observed in the diffractograms of the nanocomposites. As the WS\u003csub\u003e2\u003c/sub\u003e content in the nanocomposites was increased, the diffractograms became increasingly similar to that of the synthesized WS\u003csub\u003e2\u003c/sub\u003e. A peak emerged at approximately 33˚(2Θ) in the powder pattern of the nanocomposite that contained 20% WS\u003csub\u003e2\u003c/sub\u003e and became more prominent in the patterns of the nanocomposites consisting of 30%, 40%, and 50% WS\u003csub\u003e2\u003c/sub\u003e. Another peak near 58˚ (2Θ) was also observed in the nanocomposite containing 50% WS\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e \u003cp\u003e \u003cem\u003eRoom-Temperature Conductivity Measurements\u003c/em\u003e \u003c/p\u003e \u003cp\u003eRoom-temperature conductivity measurements were performed at 290 K in air and are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Error bars indicate the estimated uncertainty of each measurement. There are three data points at 40%: measurements on two pellets from one synthesis and one pellet from a different synthesis. There is good agreement among these three.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe conductivity of polypyrrole was found to be 11.7 ± 1.2 S/cm. This value is high and is close to the value of 10 S/cm reported in the literature where a mole ratio of 4:1 of FeCl\u003csub\u003e3\u003c/sub\u003e to the monomer was used [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. For the nanocomposites, the general trend was that the conductivity decreased with increasing WS\u003csub\u003e2\u003c/sub\u003e content. The lower conductivity of the 30% sample is not clear. This could be attributed to several factors such as significant difference in the amount of humidity during the synthesis, relatively longer time between the synthesis and conductivity measurements, and a lower pressure used for pressing the pellet.\u003c/p\u003e \u003cp\u003eThe synthesized exfoliated WS\u003csub\u003e2\u003c/sub\u003e had a conductivity too small to be measured with our system. Bulk 2H-WS\u003csub\u003e2\u003c/sub\u003e is a semiconductor whose conductivity would have been measurable. The fact that the pellets of synthesized exfoliated WS\u003csub\u003e2\u003c/sub\u003e appeared to be insulators could be due to thiourea residue coating the surface of the exfoliated WS\u003csub\u003e2\u003c/sub\u003e. The ATR-FTIR spectrum for the synthesized exfoliated WS\u003csub\u003e2\u003c/sub\u003e exhibited peaks at 1395 cm\u003csup\u003e− 1\u003c/sup\u003e, 1230 cm\u003csup\u003e− 1\u003c/sup\u003e, and 804 cm\u003csup\u003e− 1\u003c/sup\u003e, and these were attributed to decomposed thiourea on the surface of the exfoliated WS\u003csub\u003e2\u003c/sub\u003e. In fact, thiourea decomposition has been shown to begin at 140°C [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], well below the synthesis temperature of 500°C used for the exfoliated WS\u003csub\u003e2\u003c/sub\u003e. To remove the decomposed thiourea, a sample of the synthesized WS\u003csub\u003e2\u003c/sub\u003e was heated to 200°C under a dry air purge. ATR-FTIR spectra showed little change after 149 minutes of heating. It was concluded that the decomposed thiourea was strongly attached to the exfoliated WS\u003csub\u003e2\u003c/sub\u003e, possibly through covalent bonds to sulfur or dative bonds to the tungsten atoms within the layers. Higher temperatures during the cleaning or an alteration in the ratio of tungstic acid to thiourea during the synthesis could reduce contamination from decomposed thiourea.\u003c/p\u003e \u003cp\u003e \u003cem\u003eVariable-Temperature Conductivity Measurements\u003c/em\u003e \u003c/p\u003e \u003cp\u003eFollowing room-temperature measurements in air, variable-temperature conductivity measurements were performed on some of the pellets. These were done in vacuum, and the samples were kept in the vacuum chamber for at least 12 hours before measurement. At room temperature (about 290 K), the conductivity of all the synthesized materials was lower (by 8–20%) under vacuum than under atmospheric conditions.\u003c/p\u003e \u003cp\u003eAs seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, PPy and the nanocomposites showed a positive correlation between\u003c/p\u003e \u003cp\u003etemperature and conductivity. The relationship is nearly linear, very different from the exponential behavior typical of semiconductors. The temperature dependence of conductivity can be fit to an inhomogeneous conduction model [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e], which assumes there is good conduction in some regions of the material, and that these highly conducting regions are separated by poorly conducting disordered regions through which mobile charges travel by a hopping process. When hopping is the dominant effect limiting current flow, as it is in many conducting polymers and related nanocomposites, the model is equivalent to the variable-range hopping (VRH or Mott law) model [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn this model, the resistivity ρ and conductivity σ are given by:\u003c/p\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:\\rho\\:={\\sigma\\:}^{-1}={f}_{n}{\\rho\\:}_{0}{exp}\\left[{\\left(\\frac{{T}_{0}}{T}\\right)}^{\\gamma\\:}\\right]\\)\u003c/span\u003e \u003c/span\u003e, [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/p\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e \u003cp\u003ewhere T is the absolute temperature, and the other parameters are constants. In three dimensions, γ is expected to be 0.25. VRH-like conductivity with γ ≈ 0.25 has been reported in, for example, other polypyrrole/MoS\u003csub\u003e2\u003c/sub\u003e nanocomposites [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] and polyaniline/FeOCl nanocomposites [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. When equation [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] is valid, a graph of the logarithm of ρ as a function of T\u003csup\u003e− 0.25\u003c/sup\u003e will be a straight line. Such a plot is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e and demonstrates that the data are consistent with VRH conductivity.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe conductivity results suggest that charge transport in these materials proceeds mainly through the PPy fraction of the nanocomposites. Adding poorly conducting exfoliated WS\u003csub\u003e2\u003c/sub\u003e introduces additional barriers to the flow of charge and reduces the overall conductivity.\u003c/p\u003e \u003cp\u003e \u003cem\u003eSeebeck Coefficient\u003c/em\u003e \u003c/p\u003e \u003cp\u003eSeebeck coefficients for all synthesized materials are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. Error bars indicate the standard deviation of several measurements at each composition. All were small and positive, suggesting that the bulk PPy and synthesized composites were p-type conductors. The values for the Seebeck coefficients generally increased alongside the WS\u003csub\u003e2\u003c/sub\u003e content of the composites.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAs shown in the conductivity measurements, the synthesized exfoliated WS\u003csub\u003e2\u003c/sub\u003e was an insulator (2H phase), which made it impossible to measure its Seebeck coefficient. This is consistent with the literature where the Seebeck coefficient of WS\u003csub\u003e2\u003c/sub\u003e nanosheets in 2H phase could not be measured, but in the IT phase the nanosheets displayed a Seebeck coefficient of 30 µV K\u003csup\u003e–1\u003c/sup\u003e [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cem\u003eThermogravimetric analysis\u003c/em\u003e \u003c/p\u003e \u003cp\u003eThermograms obtained under air purge (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e) showed that increasing WS\u003csub\u003e2\u003c/sub\u003e content in the composites had minimal effect on thermal properties other than an increase in mass remaining at 700°C. The exception to this was the 1% WS\u003csub\u003e2\u003c/sub\u003e/PPy sample, which showed marginally lower mass at the end of the TGA run; this was attributed to random errors, as the difference was less than 1% of the initial starting mass for each (1.65% remaining mass in 1% composite versus 2.55% in the PPy sample).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eData acquired under nitrogen purge (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e) showed a different trend. Samples that contained 10% and 20% WS\u003csub\u003e2\u003c/sub\u003e by weight lost less mass across the entire heating range compared to the exfoliated WS\u003csub\u003e2\u003c/sub\u003e on its own. Excluding the 1% WS\u003csub\u003e2\u003c/sub\u003e/PPy sample, composites up to 40% WS\u003csub\u003e2\u003c/sub\u003e by weight maintained mass up to 700°C better than the WS\u003csub\u003e2\u003c/sub\u003e all by itself. This effect was not observed in the 50% WS\u003csub\u003e2\u003c/sub\u003e/PPy sample. All composite samples and PPy lost mass over a wider range of temperatures compared to the abrupt loss observed in the WS\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e "},{"header":"Conclusions","content":"\u003cp\u003eXRD confirmed that the synthesized WS\u003csub\u003e2\u003c/sub\u003e and composites were in the exfoliated state. FTIR showed that the synthesized WS\u003csub\u003e2\u003c/sub\u003e had been coated with thiourea residue that could not be removed with additional heating. It was shown with TGA that the addition of WS\u003csub\u003e2\u003c/sub\u003e did not alter the thermal stability of PPy, a trend consistent throughout all tested composites.\u003c/p\u003e\u003cp\u003eVariable-temperature conductivity measurements showed that the electrical conductivity of the synthesized composites increased with temperature, in a way consistent with a variable-range hopping model. Electrical conductivity decreased with WS\u003csub\u003e2\u003c/sub\u003e content, suggesting that charge flows mainly through the PPy regions in the composites. Synthesized WS\u003csub\u003e2\u003c/sub\u003e alone was found to be an insulator.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll authors whose names appear on the submission made substantial contributions to the conception of the work, acquisition, analysis, and interpretation of the research data; drafted the work or revised it critically for important intellectual content;approved the version to be published; and agree to be accountable for all aspects of the work.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eX.W. Lv, C.C. Weng, Y.P. Zhu, Z.Y. Yuan. Small 17 (2021). https://doi.org/10.1002/smll.202005304 \u003c/li\u003e\n\u003cli\u003eT. Lee, S.H. Min, M. Gu, Y.K. Jung, W. Lee, J.U. Lee, D. G. Seong, B.Su Kim. Chem. Mater. 27 (2015) https://doi.org/10.1021/acs.chemmater.6b02688 \u003c/li\u003e\n\u003cli\u003eJ. Zhong, S. Gao, G. Xue, B. Wang. 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Nanotechnology 29 (2018) https://doi.org/10.1088/1361-6528/aa9bfe \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-inorganic-and-organometallic-polymers-and-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"joip","sideBox":"Learn more about [Journal of Inorganic and Organometallic Polymers and Materials](https://www.springer.com/journal/10904)","snPcode":"10904","submissionUrl":"https://submission.nature.com/new-submission/10904/3","title":"Journal of Inorganic and Organometallic Polymers and Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-4769189/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4769189/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eExfoliated tungsten disulfide-polypyrrole nanocomposites were synthesized \u003cem\u003evia\u003c/em\u003e an \u003cem\u003ein-situ\u003c/em\u003e polymerization method and characterized by techniques such as powder X-ray diffraction, thermogravimetric analysis, Seebeck coefficient, and electronic conductivity measurements. The electronic conductivity was found to decrease as the mass % of tungsten disulfide (WS\u003csub\u003e2\u003c/sub\u003e) in the nanocomposites was increased. The Seebeck coefficients on the synthesized materials were small and positive, suggesting that the bulk polypyrrole and synthesized nanocomposites were p-type conductors. Addition of WS\u003csub\u003e2\u003c/sub\u003e to the polypyrrole showed no changes in thermal stability.\u003c/p\u003e","manuscriptTitle":"Exfoliated tungsten disulfide-polypyrrole nanocomposites","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-20 16:21:20","doi":"10.21203/rs.3.rs-4769189/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-08-15T19:15:08+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-15T04:29:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"184796149565039922150240624433909475294","date":"2024-08-14T01:15:47+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-12T11:08:27+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"335150352802449461578869149198515313059","date":"2024-08-10T09:03:51+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"76335110742683978411200664991317246167","date":"2024-08-09T09:50:17+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"277266528914166207665053914772015018141","date":"2024-08-09T05:35:58+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-08-08T13:16:53+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-24T15:03:41+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-07-24T11:49:22+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Inorganic and Organometallic Polymers and Materials","date":"2024-07-19T18:30:59+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-inorganic-and-organometallic-polymers-and-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"joip","sideBox":"Learn more about [Journal of Inorganic and Organometallic Polymers and Materials](https://www.springer.com/journal/10904)","snPcode":"10904","submissionUrl":"https://submission.nature.com/new-submission/10904/3","title":"Journal of Inorganic and Organometallic Polymers and Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"7db426d9-f50b-4e35-819e-8bc62839baaf","owner":[],"postedDate":"August 20th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-10-14T15:58:42+00:00","versionOfRecord":{"articleIdentity":"rs-4769189","link":"https://doi.org/10.1007/s10904-024-03388-7","journal":{"identity":"journal-of-inorganic-and-organometallic-polymers-and-materials","isVorOnly":false,"title":"Journal of Inorganic and Organometallic Polymers and Materials"},"publishedOn":"2024-10-07 15:56:49","publishedOnDateReadable":"October 7th, 2024"},"versionCreatedAt":"2024-08-20 16:21:20","video":"","vorDoi":"10.1007/s10904-024-03388-7","vorDoiUrl":"https://doi.org/10.1007/s10904-024-03388-7","workflowStages":[]},"version":"v1","identity":"rs-4769189","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4769189","identity":"rs-4769189","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}