Polymerization Of Pyrrole Research Articles

Switching CO2 Electroreduction Pathways between Ethylene and Ethanol via Tuning Microenvironment of the Coating on Copper Nanofibers

AbstractEngineering the microenvironment of electrode surface is one of the effective means to tune the reaction pathways in CO2RR. In this work, we prepared copper nanofibers with conductive polypyrrole coating by polymerization of pyrrole using polyvinyl pyrrolidone (PVP) as template. As a result, the obtained copper nanofibers Cu/Cu2+1O/SHNC, exhibited a superhydrophobic surface, which demonstrated very high selectivity for ethanol with a Faraday efficiency (FE) of 66.5 % at −1.1 V vs reversible hydrogen electrode (RHE) in flow cell. However, the catalyst Cu/Cu2+1O/NC, which was prepared under the same conditions but without PVP, possessed a hydrophobic surface and exhibited high selectivity towards ethylene at the given potentials. The mechanism for switch of reaction pathways from ethylene to ethanol in CO2RR was studied. Incorporating pyrrolidone groups into the polymer coating results in the formation of a superhydrophobic surface. This surface weakens the hydrogen bonding interaction between interfacial water molecules and facilitates the transfer of CO2, thereby enhancing the local CO2/H2O ratio. The high coverage of *CO promotes the coupling of *CO and *CHO to form C2 intermediates, and reduces the reaction energy for the formation of *CHCHOH (ethanol path) at the interface. This ensures that the reaction pathway is directed towards ethanol.

Design of thermally programmable 3D shape memory polymer-based devices tailored for endovascular treatment of intracranial aneurysms

Despite recent technological advancements in endovascular embolization devices for treating intracranial aneurysms (ICAs), incomplete occlusion and aneurysm recanalization remain critical challenges. Shape memory polymer (SMP)-based devices, which can be manufactured and tailored to patient-specific aneurysm geometries, possess the potential to overcome the suboptimal treatment outcome of the gold standard: endovascular coiling. In this work, we propose a highly porous patient-specific SMP embolic device fabricated via 3D printing to optimize aneurysm occlusion, and thus, improve the long-term efficacy of endovascular treatment. To facilitate device deployment at the aneurysm via Joule-heating, we introduce a stable, homogeneous coating of poly-pyrrole (PPy) to enhance the electrical conductivity in the SMP material. Using an in-house pulse width modulation circuit, we induced Joule-heating and characterized the shape recovery of the PPy-coated SMP embolic devices. We found that the employed PPy coating enables enhanced electrical and thermal conductivity while only slightly altering the glass transition temperature of the SMP material. Additionally, from a series of parametric studies, we identified the combination of catalyst concentration and pyrrole polymerization time that yielded the shape recovery properties ideal for ICA endovascular therapy. Collectively, these findings highlight a promising material coating for a future coil-free, personalized shape memory polymer (SMP) embolic device, designed to achieve long-lasting, complete occlusion of aneurysms.

Stearic Acid as Polymerization Medium, Dopant and Hydrophobizer: Chemical Oxidative Polymerization of Pyrrole.

In recent years, fatty acids have garnered significant attention as a natural phase-change material and a hydrophobizer due to their biocompatibility and biodegradability. In this study, the utilization of fatty acid is proposed as a polymerization medium for the first time. As a specific reaction, chemical oxidative polymerizations of pyrrole is conducted using ferric chloride as an oxidant in a stearic acid medium. The polymerizations resulted in the production of micrometer-sized polypyrrole (PPy) grains, which are aggregates of atypical primary particles with submicrometer size. The PPy grains are doped with stearic acid, suggesting that the stearic acid functioned as a dopant and a hydrophobizing agent as well as a polymerization medium. The dried PPy grains can adsorb at the air-water interface and function as a liquid marble stabilizer with light-to-heat photothermal properties. The liquid marble can move on a planar air-water interface by Marangoni flow induced by NIR laser light irradiation.

Nitrogen-doped amorphous monolayer carbon.

Monoatomic-layered carbon materials, such as graphene1 and amorphous monolayer carbon2,3, have stimulated intense fundamental and applied research owing to their unprecedented physical properties and a wide range of promising applications4,5. So far, such materials have mainly been produced by chemical vapour deposition, which typically requires stringent reaction conditions compared to solution-phase synthesis. Herein, we demonstrate the solution preparation of free-standing nitrogen-doped amorphous monolayer carbon with mixed five-, six- and seven-membered (5-6-7-membered) rings through the polymerization of pyrrole within the confined interlayer cavity of a removable layered-double-hydroxide template. Structural characterizations and first-principles calculations suggest that the nitrogen-doped amorphous monolayer carbon was formed by radical polymerization of pyrrole at the α, β and N sites subjected to confinement of the reaction space, which enables bond rearrangements through the Stone-Wales transformation. The spatial confinement inhibits the C-C bond rotation and chain entanglement during polymerization, resulting in an atom-thick continuous amorphous layer with an in-plane π-conjugation electronic structure. The spatially confined radical polymerization using solid templates and ion exchange strategy demonstrates potential as a universal synthesis approach for obtaining two-dimensional covalent networks, as exemplified by the successful synthesis of monolayers of polythiophene and polycarbazole.

Flexible and Multifunctional Pressure/Gas Sensors with Polypyrrole-Coated TPU Hierarchical Array.

A promising strategy is proposed for fabricating flexible pressure/gas sensors, which have a microprotuberance and microwrinkle structure at micropillars on their sensing substrates. The sensing substrates were prepared by compression molding thermoplastic polyurethane (TPU; an industrial grade polymer) and subsequent pyrrole polymerization. Benefiting from the hierarchical structure on the sensing substrates, the flexible sensors exhibit high performances in detecting both pressure and ammonia (NH3). Mechanism for the functionalities of the hierarchical structure of the pressure sensors was analyzed. Such unique hierarchical structure endows the interlocked pressure sensor by assembling the substrates prepared at 60 min polymerization time with a relatively high sensitivity in a wider linearity range (1.15 kPa-1, 0-800 Pa), a lower detection limit of 6.2 Pa, and shorter response and recovery times (26/28 ms). The combination of stronger interfacial interaction between the TPU and polypyrrole layer, the mutual support of the interlocked micropillars, and the inherent high resilience of TPU endows the pressure sensor with lower hysteresis, good repeatability and stability, and higher durability (10,000 cycles). The interlocked pressure sensor can detect full-range human physiological activities from weak physiological signals (such as face muscle contraction, heartbeat, and breath) to body movements (such as head, elbow, and foot movement). The gas sensor assembled with the hierarchical sensing substrate prepared at 60 min polymerization time exhibits selective, stable, and faster sensing responses to NH3. The proposed facile and cost-effective preparation strategy can be an excellent candidate for fabricating high-performance and multifunctional sensors.

Removal of Arsenic from Contaminated Water by Polypyrrole-Based Adsorbents

Worldwide, there is growing concern over the toxicity of arsenic in drinking water. The US Environmental Protection Agency and Central Pollution Control Board (India) have set a safe limit of 50 parts per billion for arsenic in drinking water. Millions of people are at immediate risk due to high concentrations of arsenic in drinking water, particularly in developing nations where arsenic poisoning symptoms have been observed. One of the essential techniques described in this article is the absorption of arsenic from contaminated water by sustainable cellulosic materials like jute and wood sawdust after suitable modification. Jute and sawdust are cheap and abundantly available in South Asia. They are functionalized with polypyrrole coating by in situ chemical polymerization of pyrrole in aqueous medium in the presence of ferric chloride. Polypyrrole-coated jute fabric (with 11.28% polypyrrole add-on) and polypyrrole-coated sawdust (with 5.28% polypyrrole add-on) are found to be excellent adsorbers of arsenic ion (As3+) from water. The effect of dosage of polypyrrole-coated adsorbents, treatment time and pyrrole concentration on the As removal efficiency have been investigated in this work. The arsenic concentration in water is determined using a microwave plasma atomic emission spectrometer with the highest level of accuracy. Maximum As removal efficiency by the polypyrrole-coated sawdust and polypyrrole-coated jute fabric is found to be 80.90% and 97.3%, respectively, from a 50 mL, 7.5 parts per million As solution with a dosage of 1 g at neutral pH. The polypyrrole-coated jute and sawdust are characterized by Fourier-transform infrared spectroscopy to understand the chemical interaction between cellulose and polypyrrole molecules. The scanning electron microscope studies reveal a uniform coating of polypyrrole around the surface of jute fibre and sawdust particles. Thermo-gravimetric analysis shows good thermal stability of jute and sawdust after polypyrrole coating.

Corrosion characteristics of PPY/GO/CuO nano-composite powder reinforced epoxy coatings on IF steel

The present study has been designed to test the corrosion performance of epoxy based nano-composite coatings on Interstitial Free (IF) steel. PPy and PPy nano-composite powders were formed by polymerization of pyrrole using ferric chloride oxidant. PPy nano-composite powders were synthesized including Graphene oxide (GO) and Copper oxide (CuO) nano-particles. Four combinations have been undertaken in this study viz. pure PPy, PPy-GO (PG), PPy-CuO (PC) and PPy-GO-CuO (PGC). SEM/EDS and XRD results validated the uniform embedding of nano-particles in the pyrrole matrix during polymerization. Moreover, TGA analysis has also confirmed the enhancement of thermal stability of PPy with the incorporation of nano-particles. Further, epoxy (EP) powder was loaded with different concentration of synthesized composite powders to optimize the weight percent (wt%) of PPy, GO and CuO for testing the corrosion characteristics. The different coating configurations were applied on IF steel samples and electrochemical & salt spray testing have been conducted. It has been concluded that coating configuration EP/P2G0.5C1.0 has shown maximum corrosion protection efficiency (ηPE) of approximately 99 %. Moreover, other three configurations EP/P2, EP/P2G0.5 and EP/P2C1.0 have also shown noteworthy results of ηPE of 85, 96 and 97 % respectively. SEM images for cross-sectional view of coatings have also confirmed the uniformity of coatings on to the IF steel. The suitability of these synthesized coatings has also been verified via adhesion test evidencing no significant change in adhesive strength.

Facile One-Pot Preparation of Polypyrrole-Incorporated Conductive Hydrogels for Human Motion Sensing.

Conductive hydrogels have been widely used in soft robotics, as well as skin-attached and implantable bioelectronic devices. Among the candidates of conductive fillers, conductive polymers have become popular due to their intrinsic conductivity, high biocompatibility, and mechanical flexibility. However, it is still a challenge to construct conductive polymer-incorporated hydrogels with a good performance using a facile method. Herein, we present a simple method for the one-pot preparation of conductive polymer-incorporated hydrogels involving rapid photocuring of the hydrogel template followed by slow in situ polymerization of pyrrole. Due to the use of a milder oxidant, hydrogen peroxide, for polypyrrole synthesis, the photocuring of the hydrogel template and the growing of polypyrrole proceeded in an orderly manner, making it possible to prepare conductive polymer-incorporated hydrogels in one pot. The preparation process is facile and extensible. Moreover, the obtained hydrogels exhibit a series of properties suitable for biomedical strain sensors, including good conductivity (2.49 mS/cm), high stretchability (>200%), and a low Young's modulus (~30 kPa) that is compatible with human skin.

Effective move of Polypyrrole/TiO2 hybrid nanocomposites on removal of methylene blue dye by photocatalytic activity

Polypyrrole (PPy) was synthesized effectively by chemical oxidative polymerization of pyrrole. Organic-inorganic hybrid materials PPy-TiO2 with different PPy weight percents were prepared by mechanical mixing, by using titanium oxide nanoparticles. The characterizations of PPy-TiO2 hybrid nanocomposites were analyzed by FTIR, UV–Vis, XRD, TGA & DSC and SEM & EDAX. Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) were used to distinguish the structure of the attained PPy-TiO2 hybrid nanocomposites. UV–vis techniques are proved the polymerization of pyrrole monomer and the strong interaction between PPy and TiO2 nanoparticles. Thermogravimetric analyzer (TGA-DSC) curves revealed that TiO2 can decrease the weight loss of nanocomposite and increase the thermal stability of synthesized nanocomposites. The residual mass of the pure Pyy-36.51 %, PPy-TiO2 (25 %)-64.82 %, PPy-TiO2 (50 %)-60.82 %, PPy-TiO2 (75 %)-70.50 % and pure TiO2- 96.69 % nanocomposites at the residual temperature 497.80 °C. The morphology and molecular structure of the hybrid nanocomposite were characterized by scanning electron microscope & Energy dispersive X-ray analysis spectroscopy (SEM & EDAX). These characterization results confirmed the polymerization of pyrrole and the strong interaction between PPy and TiO2. The material with outstanding absorption capability that meet in optical application is the challenging way, thus the photocatalytic analysis of PPy-TiO2 hybrid nanocomposites is merely a admissible results. It is notably the favorable degradation efficiency of pure PPy, the PPy+TiO2 (25 % 50 % & 75 %) nanocomposites are 82 %, 66 %, 67 % and 53 % respectively.

Polypyrrole nanoclips-coated Co/C nanostructures with enhanced microwave absorption

There is a challenge to boost the electromagnetic wave absorption performance of magnetic carbon-based materials by rationally adjusting the structure of MOF. In this paper, nanoclip-shaped polypyrrole (PPy) was wrapped on the surface of the Co/C nanoparticle derived from Co-MOF via in-situ polymerization of pyrrole with the help of cetylammonium bromide. The electromagnetic parameters of prepared Co/C@PPy can be easily tuned by adjusting the feed ratio of PPy to Co/C. The optimum value of reflection loss (RL) for Co/C@PPy is −45.49 dB at 2.4 mm and 15.12 GHz when the feed ratio of pyrrole to Co/C is 200 μL to 80 mg, and the effective absorption bandwidth (EAB, RL ≤ −10 dB) reaches 5.97 GHz (11.76–17.73 GHz) at the matching thickness of 2.5 mm. This study paves the way for further design and preparation of the nanocomposites based on MOF-derived nanostructures with excellent EMW absorption performance.

(Digital Presentation) Synergistic Enhancement of Thermoelectric Performance through One-Dimensional Hybrid Nanocomposites: Wrapped Nickel Oxide-Decorated Multi-Walled Carbon Nanotubes with Polypyrrole

Given the drawbacks of organic materials’ thermoelectric (TE) conversion efficiency, an approach has been made in this study to synthesize a hybrid organic-inorganic material based on polypyrrole (PPy), multi-walled carbon nanotubes (MWCNTs) and nickel oxide nanoparticles (NiO). The nanocomposite is formed through three steps: MWCNTs functionalization via diazonium salt grafting of 5-amino-1,2,3-benzene tricarboxylic acid; in situ generation on their surfaces of NiO nanoparticles with a homogenous distribution; the chemical polymerization of pyrrole using methyl orange as templating and dopant to wrap the MWCNTs-(COOH)3-NiO. To explore the structural and physical properties of the fillers and the nanocomposites, X-ray diffraction (XRD), Transmission electron microscopy (TEM), Raman spectrometer, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were used. Thereby investigating the electrical conductivity (𝜎), Seebeck coefficient (S) and thermal conductivity (κ) at room temperature, a promising improvement was observed in PPy-MWCNTs-(COOH)3-NiO compared to pure PPy. The observed enhancements in TE properties (ZTPPy-MWCNTs-(COOH)3-NiO = 1.51×10-2) are attributed to the presence of NiO, which acts as a dopant and improves the charge carrier density in the nanocomposite; this result could be increased at higher temperatures. Overall, these results demonstrate the potential of our approach for developing high-performance TE materials with applications in energy harvesting and waste heat recovery. Furthermore, this approach offers the potential for scalability and reproducibility, making it a promising method for large-scale fabrication of high-performance composites. Figure 1

Reduced Graphene Oxide Wrapped Polypyrrole on Carbon Cloth for High‐Performance Flexible Solid‐State Supercapacitors

AbstractThe nature of rigidity and low energy density of polypyrrole (PPy)‐based electrodes limits their wide application in flexible energy storage devices. In this study, reduced graphene oxide (rGO) wrapped polypyrrole (PPy)/oxidized carbon cloth (OCC) (rGO@PPy/OCC) is prepared by the polymerization of pyrrole using MnO2 as the oxidant on the surface of OCC followed by the adsorption and reduction of graphene oxide (GO). The prepared rGO@PPy/OCC electrode exhibits a high gravimetric specific capacitance of 547 F g−1 at a current density of 0.5 A g−1 and a high area specific capacitance of 1641 mF cm−2 at a current density of 1.5 mA cm−2. It nearly maintains the initial capacitance after 8000 cycles at a high scan rate of 200 mV s−1 and at a large current density of 10 A g−1. Moreover, the flexible rGO@PPy/OCC electrodes are used to construct flexible solid‐state supercapacitors (FSSC). The FSSC based on rGO@PPy/OCC exhibits a high energy density (33.89 Wh kg−1 and 101.81 µWh cm−2) and a capacitance retention of 95.10% after 1000 bending cycles, demonstrating the excellent cycling stability and flexibility. Therefore, it is potential for rGO@PPy/OCC as a flexible electrode to fabricate high‐performance FSSC.

High‐Performance Textile‐Based Capacitive Strain Sensors via Enhanced Vapor Phase Polymerization of Pyrrole and Their Application to Machine Learning‐Assisted Hand Gesture Recognition

Sensors based on everyday textiles are extremely promising for wearable applications. The present work focuses on high‐performance textile‐based capacitive strain sensors. Specifically, a conductive textile is obtained via vapor‐phase polymerization of pyrrole, in which the usage of methanol co‐vapor and the addition of imidazole to the iron chloride oxidant solution are shown to maximize conductivity. A technique to provide insulation and mechanical resistance using thermoplastic polyurethane and polystyrene‐block‐polyisoprene‐block‐polystyrene/barium titanate composite is developed. Such insulated conductive elastics are then used to fabricate highly sensitive twisted yarn capacitive sensors. A textile glove is subsequently embedded with such sensors. The wireless measurement and transmission system demonstrate efficacy in capturing capacitance variations upon strain and monitoring hand motions. A machine learning model to recognize 12 gestures is implemented—100% classification accuracy is obtained.

Doping P heteroatoms into thin-wall polypyrrole hollow nanobelts with enhanced electrochemical performance for aqueous Zn ion storage

The aqueous zinc-ion batteries are promising to be large-scale energy technologies for solving the contradiction between the intermittency of renewable energy and the immediacy of growing electricity demand. Conductive polymers have been utilized as cathode materials for Zn ion storage but suffered from inadequate active sites, resulting in poor specific capacity. In this work, P doping polypyrrole hollow nanobelts (P-PPy HNBs) with long aspect ratio have been prepared by in-situ polymerization of pyrrole on a template of MoO3 nanotubes. Owing to the long-aspect-ratio hollow structure, the P-PPy HNBs perform thin wall, large surface area, porous structure with micropores and mesopores, which is beneficial to high and fast Zn ion storage. Remarkably, the as-obtained P-PPy HNBs cathodes in this work deliver favorable electrochemical performance for Zn2+ storage in terms of good capacity, rate capability and cycling stability. Moreover, kinetic analysis quantitatively confirms the capacitive contribution of NPCNTs is dominant for aqueous Zn ion storage. The capacitive properties are contributed that the synergistic effect of porous and hollow nanobelt structure construction and P doping strategy can provide abundant active sites and promote electronic conductivity and ion transport. Generally, the strategy for hollow structure with a long aspect ratio and heteroatom doping in our work causes excellent-performance properties, possibly bringing light on the future design of other cathodes for aqueous Znic-based energy storage devices.

Designable polypyrrole pattern in hydrogel achieved by photo‐controllable concentration of Fe3+ initiator

AbstractConductive polymer hydrogels (CPHs) are promising in cutting‐edge applications including bioelectronics and tissue engineering. However, the precise regulation of the spatial distribution of the conductive polymer (CP) in the hydrogel network is still an issue for designing a smart material. Herein, we propose a facile method for preparing CPH‐based smart materials by controlling the distribution of Fe3+ initiator with UV light irradiation. Thus, designable polypyrrole (PPy) conductive patterns in the polyvinyl alcohol/sodium alginate (PVA/SA) semi‐interpenetrating hydrogel network are demonstrated by controlling the concentration of Fe3+ ions coordinated with carboxylate groups. Depending on the irradiation time, the reduction of Fe3+ to Fe2+ occurs in different extents. As a result, the controllable polymerization of pyrrole only initiated by Fe3+ is achieved to form desirable CPH patterns, which are confirmed by the characterization results of Fourier transform infrared spectrometry, X‐ray photoelectron spectroscopy, and scanning electron microscopy. Moreover, the developed hydrogel with PPy patterns is illustrated for the application in smart conductive circuit and information encryption. The simple procedure and the controllable conductive patterning of the proposed method make it a promising route in developing smart hydrogel materials, which can be extended to other Fe3+ initiated CP patterns.

EMI-shielding response of GO/Fe3O4/polypyrrole(PPy)/thermoplastic polyurethane (TPU) composites

In the present study, thermoplastic polyurethane was reinforced with GO/Fe3O4/PPy nanocomposites with varying GO:Fe3O4 ratio to develop high-performance electromagnetic interference (EMI) shields. GO/Fe3O4/PPy fillers were prepared by adding polypyrrole (PPy) nanotubes, synthesized by the soft-template method from oxidative polymerization of pyrrole, to graphene oxide decorated with Fe3O4 nanoparticles prepared by a sonochemical method. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy were performed to reveal the structural and morphological properties of GO/Fe3O4/PPy nanofillers, and the structure and thermal properties of the GO/Fe3O4/PPy/TPU nanocomposites was studied by cryofracture SEM and thermogravimetry (TGA). The effect of GO:Fe3O4 ratio on the electrical conductivity, magnetic permeability, permittivity, and electromagnetic-wave-shielding performance of GO/Fe3O4/PPy/TPU nanocomposites was investigated in the X-band frequency range. The maximum EMI efficiency was 4.81 dB with increasing GO:Fe3O4 ratio in GO/Fe3O4/PPy/TPU composites, with blocking of 66.72 % of the incident electromagnetic wave.

Facile controllable sequential electrochemical in-situ synthesis of Fe3O4/PPY hybrid electrode for supercapacitor

In this work, a facile sequential electrochemical synthesis strategy is employed for the precisely controlled in situ polymerization of pyrrole on an iron oxide substrate in the oxalic acid system. The use of porous iron oxide as a template allows for the modification of polypyrrole to create a large conductive network while preserving the integrity of the substrate. This process improves the poor conductivity of conventional metal oxides, allowing for the synthesis of a Fe3O4/PPY hybrid electrode material. The experiments elucidated the mechanism of pyrrole surface morphology coupled with the deposition amount threshold affecting the electrode performance. This was achieved by elucidating the regulation laws of key deposition process parameters (pyrrole monomer concentration, scanning rate, and number of cycles) on the diffusion and oxidation behaviors of pyrrole during the continuous polymerization process. Furthermore, the electrochemical behaviors of the Fe3O4/PPY hybrid electrode were better resolved. The results demonstrate that the deposition amount of PPY on the Fe3O4/PPY hybrid electrode material is within the optimized threshold (1 × 10−6∼3 × 10−6 g), exhibiting a regular and uniform surface morphology with no agglomeration, which indicates a competitive specific capacitance (215.12 mF cm−2 at 1.1 mA cm−2). This strategy of structure-modulated synergistic functional hybridization offers a new approach for designing efficient binder-free hybridized electrode materials.

Ultra-high performance of PPy/MoS2 2D nanocomposites for ammonia sensing

The synergistic interaction between Polypyrrole/Molybdenum disulfide at the interface makes their nanocomposites ideal for gas sensing applications. In this work, PPy/MoS2 (1 wt%, 5 wt%, 10 wt%, 20 wt% and 30 wt%) based nanocomposites have been prepared by in-situ chemical oxidative polymerization of pyrrole. In these nanocomposites, pyrrole acts as a matrix component and MoS2 as filler, which is finally loaded on interdigitated electrodes. In a significant development for large-scale production, the gas sensor fabrication process was designed to be both cost-effective and easy to operate. This paves the way for wider commercialization. The optimized sensor made from PPy and MoS2 with 5 wt% of MoS2, demonstrates excellent sensing performance. It has a sensitivity of 21.65 % for 100 ppm gas exposure, along with fast response and recovery times of 340 seconds and 680 seconds, respectively. It also shows a high response towards NH3 compared with pure PPy. In addition, high repeatability and long-term stability of prepared nanocomposites have also been observed over a concentration range of 10–200 ppm. This material stands out for its strong response to ammonia gas compared to other detectable gases. These results render the PPy/MoS2 nanocomposite a promising candidate for high-performance NH3 sensing at 28 ̊C. The underlying sensing mechanism of the PPy/MoS2 sensing device towards NH3 gas was systematically discussed which is attributed to the synergistic effect of binary nanocomposites.

Oxidative MnO2 Template Assisted Electrochemical Fabrication of Graphene/Polypyrrole Supercapacitor Electrodes.

Improving the morphological structure of active materials is a reliable strategy for the fabrication of high-performance supercapacitor electrodes. In this study, we introduce a feasible approach to constructing the graphene/polypyrrole (PPy) composite film implanted onto the current collector through a two-step electrochemical deposition method utilizing MnO2 as an intermediary template. The reduced graphene oxide (rGO) hydrogel film is first hydrothermally grown on a carbon cloth (CC) substrate to obtain a porous rGO@CC electrode on which MnO2 is electrodeposited. Then the as-prepared rGO/MnO2@CC electrode is subjected to the electrochemical polymerization of pyrrole, with MnO2 acting as an oxidizing template to facilitate the oxidative polymerization of pyrrole, ultimately yielding an rGO/PPy composite film on CC. The PPy synthesized via this methodology exhibits a distinctive interconnected structure, resulting in superior electrochemical performance compared with the electrode with PPy directly electrodeposited on rGO@CC. The optimized electrode achieves an impressive specific capacitance of 583.6 F g-1 at 1 A g-1 and retains 83% of its capacitance at 20 A g-1, with a capacitance loss of only 9.5% after 5000 charge-discharge cycles. The corresponding all-solid-state supercapacitor could provide a high energy density of 22.5 Wh kg-1 and a power density of 4.6 kW kg-1, with a capacitance retention of 82.7% after 5000 charge-discharge cycles. Furthermore, the device also demonstrates good flexibility performance upon bending at 90 and 180°. This work presents an innovative method for the preparation of carbon material/conducting polymer electrodes with specific structural characteristics and superior performance.

Polypyrrole Coating via Lemieux-von Rudloff Oxidation on Magnetite Nanoparticles for Highly Efficient Removal of Chromium(VI) from Wastewater.

An alternative way for the coating of polypyrrole (PPy) polymer on hydrophobic magnetite (Fe3O4) nanoparticles is reported here to capture toxic chromium ions, Cr (VI), present in water. Iron oxide magnetic nanoparticles (Fe3O4) were synthesized by the conventional coprecipitation technique using FeCl3·6H2O and FeSO4·7H2O iron precursors and subsequently modified with oleic acid (OA). Then OA-Fe3O4 hydrophobic nanoparticles were oxidized using the Lemieux-von Rudloff reaction to transfer OA into hydrophilic azelaic acid (AA) (HOOC(CH2)7COOH-modified magnetic nanoparticles (AA-Fe3O4). Finally, a PPy polymer coating was formed by a seeded polymerization of pyrrole, using AA-Fe3O4 as seeds. The average size of PPy/Fe3O4 nanocomposites is 12.33 nm and is almost spherical in shape. The surface composition is confirmed by FTIR and thermogravimetry analyses. An X-ray diffraction study confirmed the formation of highly crystalline Fe3O4 nanoparticles, and the crystallinity was retained after the surface modification. The adsorption study suggested that the Cr(VI) ion adsorption is highly pH-dependent and the maximum amount of adsorption is obtained at pH 2.0. The adsorption results revealed that the Langmuir model provided the best fit for the isotherm, with a maximum adsorption capacity reaching approximately 173.22 mg g-1 at 323 K. Spontaneous and endothermic adsorption processes were confirmed by evaluating the thermodynamic parameters obtained in this investigation. The kinetics study showed that the interaction between Cr(VI) ions and magnetic nanocomposites was directed by a pseudo-second-order rate process indicating chemisorption. The prepared PPy/Fe3O4 nanocomposites would be promising adsorbents to purify water by eliminating Cr(VI) metal ions from wastewater.