Nanostructured Polypyrrole Research Articles

The Alphabet of Nanostructured Polypyrrole.

This review is devoted to polypyrrole and its morphology, which governs the electroactivity of the material. The macroscopic properties of the material are strictly relevant to microscopic ordering observed at the local level. During the synthesis, various (nano)morphologies can be produced. The formation of the ordered structure is dictated by the ability of the local forces and effects to induce restraints that help shape the structure. This review covers the aspects of morphology and roughness and their impact on the final properties of the modified electrode activity in selected applications.

Bacteria-imprinted impedimetric sensor based on doping-induced nanostructured polypyrrole for determination of Escherichia coli.

Asimple and label-free bacteria-imprinted impedimetric (BIP) sensor for the sensitive measurement of Escherichia colihas been developed. The BIP sensor is fabricated by one-step electropolymerization of pyrrole (functional monomer), copper phthalocyanine-3, 4', 4'', 4'''-tetrasulfonic acid tetrasodium salt (CuPcTs, dopant), and target bacteria (E. coli O157:H7) on aglassy carbon electrode. After the removal of the bacterial template, the established imprinted sites on the CuPcTs-doped polypyrrole film (PPy/CuPcTs) enable the highly selective rebinding of target bacteria and the resulting impedance change of the sensing interface is used to detect the target bacteria. We found that during the electropolymerization process, CuPcTs induced pyrrole to form granular-like nanostructured PPy/CuPcTs with excellent conductivity compared with the PPy film, substantially improving the sensitivity of the proposed sensor. The sensor presented a wide detection range (102 ~ 107CFU⋅mL-1, RSD 1.1% ~ 3.5%) with a limit of detection of21CFU⋅mL-1. Furthermore, the proposed sensor effectively distinguished E. coli O157:H7 from other non-target bacteria and exhibited good practicality with recoveries from 91 to 103% in spiked real samples, indicating the potential utility of the sensor in food safety and environmental monitoring.

Robust and versatile polypyrrole supramolecular network packed photothermal aerogel for solar-powered desalination

Solar-powered desalination is an emerging and sustainable water purification technology, that extends accessible clean water to relieve global water scarcity. Although great achievements have been made to develop interfacial photothermal materials, it is still challenging to simultaneously achieve high-level evaporation rates (>3 kg·m−2·h−1, 1 sun) and high-efficient energy conversion (>95 %) under 1 sun illumination. Herein, a polypyrrole supramolecular network-packed photothermal aerogel is designed and developed as solar-thermal evaporator to boost highly efficient solar-powered desalination. The photothermal aerogel integrates the photothermal, hydrophilic, and nanostructured polypyrrole supramolecular network to intensify solar-thermal energy utilization and reduce evaporation enthalpy, and the heat-insulating polysiloxane aerogel to enable mass transfer and suppress heat loss. The combined merits of the polypyrrole supramolecular network-packed photothermal aerogel promise outstanding evaporation rate of 3.61 kg·m−2·h−1 and remarkable solar-to-vapor conversion efficiency of 97.1 % under 1 sun illumination. Furthermore, polypyrrole supramolecular network imparts reliable salt resistance, cyclic stability, and environment tolerability for potential applications in solar seawater desalination. The comprehensive performance has considerable advantages over state-of-the-art materials. The study provides a new paradigm for the design of solar-thermal composites to advanced solar-powered desalination and contributes to future sustainable environmental and energy applications.

Ammonia gas-sensing behavior of uniform nanostructured PPy film prepared by simple-straightforward in situ chemical vapor oxidation

Abstract A highly uniform nanostructured polypyrrole (PPy) film prepared by a simple, straightforward in situ route of chemical vapor oxidation has been demonstrated as a sensitive substrate for NH3 gas sensing. The structure of PPy film was investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The binding characteristics of the functional groups of the PPy film were examined by Fourier transform infrared and Raman spectroscopy. NH3 sensing properties of the PPy film were evaluated by its resistive response to gas concentrations from 45 to 350 ppm at different temperatures ranging from 25 to 100°C. The sensing response maximum value was 142.6% when exposed to 350 ppm of NH3 gas at room temperature (25°C). The sensing response of PPy film shows an excellent linear relationship and high selectivity toward NH3. The NH3 sensing mechanism is due to the physisorption and chemisorption interactions of NH3 molecules and the adsorptive sites of PPy (polaron and bipolaron charging carriers).

Highly Sensitive Ammonia Sensor Based on Modified Nanostructured Polypyrrole Decorated With MAF-6 to Reduce the Effect of Humidity

An ammonia gas sensor based on nanostructured polypyrrole functionalized by carboxylic groups (PPy-COOH) was prepared and characterized. The active layer was deposited on a ceramic substrate with gold interdigital electrodes by a low-cost airbrush-spray coating technique, and the sensor exhibited a strong response to ammonia ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Z}/{Z}_{{0}}\,\,=$ </tex-math></inline-formula> 5.48 at 100 ppm) in comparison with pure PPy ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Z}/{Z}_{{0}}\,\,=$ </tex-math></inline-formula> 1.5 at 100 ppm). Cross-sensitivity measurement showed a more significant response to relative humidity (RH) and so two approaches were used to reduce this undesirable humidity dependence: 1) the creation of a hydrophobic metal-organic framework (so-called MAF-6) on the PPy-COOH layer and 2) the fabrication of a heterostructure of PPy-COOH with multiwall carbon nanotubes (MWCNTs). Both approaches resulted in a significant reduction in the humidity dependence of the sensor, from the value <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Z}/{Z}_{{0}}\,\,=$ </tex-math></inline-formula> 0.02 (PPy-COOH) to 0.404 and 0.427 for PPy-COOH-MAF-6 and PPy-COOH/MWCNT, respectively. However, the samples coated with MAF-6 showed a smaller decrease in response to ammonia. In addition, the proposed approach with MAF-6 functionalization allowed ammonia detection within a broader RH range (up to 60% RH) compared to the PPy-COOH sensing layer. The presence of MAF-6 on the surface of PPy-COOH was further verified by infrared spectroscopy (FTIR), X-ray diffraction (XRD) spectroscopy, and scanning electron microscopy together with energy-dispersive X-ray spectroscopy (SEM-EDX). The sensing mechanisms of ammonia and RH of the PPy-COOH material are also discussed in this article.

Facile Construction of Three-Dimensional Architectures of a Nanostructured Polypyrrole on Carbon Nanotube Fibers and Their Effect on Supercapacitor Performance

Conducting polymer and carbon nanotube hybrids have been researched intensively in recent years for electrodes of fiber-shaped supercapacitors (FSSCs) toward flexible and wearable energy storage devices. Here, three-dimensional (3D) hierarchical polypyrrole (PPy)/carbon nanotube fiber (CNTF) architectures have been prepared by a facial electrodeposition method for flexible FSSC electrodes. PPy nanoparticles, vertically aligned nanowire arrays (VANAs), and nanowire networks were synthesized on CNTFs, respectively, to construct three types of 3D architectures by controlling the electrodeposition condition of PPy. The influence of the 3D architectures of PPy/CNTF electrodes on the performance of the assembled quasi-solid-state FSSCs has been carefully studied. The FSSCs with PPy VANAs showed a much higher specific capacitance than that with PPy nanoparticles because the hierarchical porous structure of PPy VANAs provides a higher accessibility of electrolytic ions and a higher Coulombic efficiency than that with the PPy nanowire network. The PPy VANA-/CNTF-based FSSCs displayed high flexibility, stability, and a specific capacitance of 178.14 F g–1 at 0.4 A g–1, which is much higher than that based on common PPy cauliflower-like film/CNTF electrodes (92.06 F g–1) and pure CNTF electrodes (8.48 F g–1) under the same conditions, demonstrating the great advantages of the 3D hierarchical structure.

Simple Polypyrrole Based Preparation for Fe-N-C Catalysts for the Oxygen Reduction Reaction

Hydrogen based fuel cells could play an imprtant role for future CO2-free energy supply, especially with respect to the transportation and automotive sector. However, efficient fuel cell catalyst mostly rely on the precious metal platinum. The contributions of platinum based catalysts and their application are estimated with up to 40% of the overall stack costs [1], [2]. Furthermore, taking into account the released CO2 equivalents, soil acidification and fresh water consumption the mining and production of precious metals leaves a great ecological foot-print [3].FeNC catalysts are a promising alternative to replace platinum for the oxygen reduction reaction. However, still several challenges need to be faced. A low voumetric activity, a poor long-term stability in the device and difficuilties during scale-up of the preparation procedure are the main issues. Especially for the high performing catalysts that are based on zeolitic imidazolate frameworks (ZIFs) [4], [5], the scale-up of the ZIF synthesis and subsequent FeNC preparation seems difficuilt while maintaining the same material properties [6], [7].Here, we present a simple prepration for FeNC catalysts that relys on nanostructured polypyrrole. Because the presented method is based on a simple polymer the scale-up seems easier in realizationWe will discuss the impact of different aspects as amount and kind of iron precursor, level and kind of doping agents, and pyrolysis temperature and their impact on fuel cell performance data and structural composition. The variation of these aspects leads to significant variation in structural composition, activity, selectivity and stability of these catalysts. For example, very low levels of hydrogen peroxide formation are found even for low catalyst loadings during RRDE [8]. Further, by an increase of the pyrolsis temperature from 800°C to 1000°C the retained current density after 50 hours of potentiastatic testing at 0.5 V could be increased by a factor of 1.6.[1] S.T. Thompson, D. Papageorgopoulos, Platinum group metal-free catalysts boost cost competitiveness of fuel cell vehicles, Nat Catal, 2 (2019) 558-561. [2] A.R. Wilson, J.P. Marcinkoski, D., Fuel Cell System Cost, DOE Hydrogen and Fuel Cells Program Record, in Departement of Energy, 2016. [3] P. Nuss and M.J. Eckelmann, PLOS one, Vol. 7 Life Cycle Assessment of Metals: A Scientific Synthesis, 2014. [4] E. Proietti, F. Jaouen, M. Lefevre, N. Larouche, J. Tian, J. Herranz, J.-P. Dodelet, Nature Commun., 2, 416, 2011. [5] D. Zhao, J.-L. Shui, L. R. Grabstanowicz, C. Chen, S. M. Comment, T. Xu, J. Lu, D.-J. Liu, Adv. Mater., 26, 7, 2013. [6] M. Hovestadt, J. Vargas Schmitz, T. Weissenberger, F. Reif, M. Kaspereit, W. Schwieger, M. Hartmann, Scale-up of the Synthesis of Zeolitic Imidazolate Framework ZIF-4, Chem-Ing-Tech, 89 (2017) 1374-1378. [7] T. Johnson, M.M. Lozinska, A.F. Orsi, P.A. Wright, S. Hindocha, S. Poulston, Improvements to the production of ZIF-94; a case study in MOF scale-up, Green Chem, 21 (2019) 5665-5670. [8] L. Ni, C. Gallenkamp, S. Paul, M. Kübler, P. Theis, S. Chabbra, K. Hofmann, E. Bill, A. Schnegg, B. Albert, V. Krewald, U. I. Kramm, Active Site Identification in FeNC Catalysts and Their Assignment to the Oxygen Reduction Reaction Pathway by In Situ 57Fe Mössbauer Spectroscopy, Adv. Energy Sustainability Res., 2, 2021

High-Performance Multiresponsive Bilayer Actuators Based on Micro-/Nanostructured Polypyrrole for Robust Smart Devices

Bioinspired soft actuators have great application potentials in many fields. However, so far, it has remained a great challenge to realize high-performance actuators with a low-cost manufacturabili...

Polypyrrole and enzyme free cholesterol flakes based composite: Selective determination of theophylline

In the present work, we demonstrated the non-enzymatic theophylline (TP) detection using nanostructured Polypyrrole (Ppy) and Cholesterol (Ch) flakes coordinated nanocomposite coated on Glassy Carbon Electrode. The higher active surface area and good mechanical stability of the Ppy integrated Ch composite exhibited better oxidation towards TP. The electron transfer across hydrogen bonding is of fundamental importance in enhancing the biochemical process in this biosensor system. Further, the scan rate analysis confirmed the quasi-reversible diffusion controlled electrochemical process. The differential pulse voltammetry report of the electrocatalyst shows a linear response of TP in the concentration range 1μM – 1 mM with detection limit of 720 nM (S/N = 3σ/b). The proposed electrochemical sensor exhibited intriguing sensing properties with good selectivity, reproducibility towards TP detection without any surface fouling. The overall analysis confirmed that the prepared nanocomposite modified electrode has quantified better accuracy towards target molecule without the aid of any bio receptors and binders in tea leaves and human urine samples.

Metal–organic framework of nanostructured polypyrrole incorporated with TiO2 nanoparticles for supercapacitor electrode

Metal–organic framework of nanostructured polypyrrole incorporated with TiO2 nanoparticles for supercapacitor electrode

Charge Transport and Gradient Doping in Nanostructured Polypyrrole Films for Applications in Photocurrent Generation

The investigation of the charge-transport mechanism across disordered conducting and semiconducting materials is of relevance, considering the applications in modern organic and hybrid electronics....

Simultaneous determination of sertraline, imipramine and alprazolam in human plasma samples using headspace solid phase microextraction based on a nanostructured polypyrrole fiber coupled to ion mobility spectrometry

PPy-DBS was synthesized by an electrochemical process and used as a HS-SPME fiber for determination of antidepressants in plasma without derivatization steps.

E-DNA biosensors of M. tuberculosis based on nanostructured polypyrrole.

The objective of this paper is to demonstrate the potential of nanostructured polypyrrole formed by template free as platform for amperometric detection of DNA. The nanowires of polypyrrole (nw-PPy) are formed through electrochemical polymerization and chemically modified by electrochemical oxidation of ethylene diamine or dendrimers PAMAM to obtain aminated surface. The DNA probe and ferrocenyl group, as redox reporter, were covalently linked to the surface of nw-PPy. The chemical structure of nanostructured platform was characterized through SEM, FT-IR and XPS and the electrochemical properties through cyclic voltammetry and electrochemical impedance spectroscopy (EIS). We show that the properties of nw-PPy such as, hydrophilic character and large surface area have large effect on the electronic properties. Thus, the electrochemical performance is increased compared to others nanomaterials considering the obtained value of the rate of electron transfer of 18 s-1. These properties allow enhanced DNA sensing where detection limit of 0.36 atomolar without any amplification step. The biosensor can be applied in detection of genomic DNA of Mycobacterium tuberculosis and the mutated one which present the resistance to rifampicin and large selectivity was demonstrated. We believe that nw-PPy modified with redox marker is a promising platform for electrochemical biosensors and can be applied for various diagnosis prospects.

Tuning the morphologies and electrical properties of azobenzene-4,4′-dicarboxylate-doped polypyrrole via ultraviolet light irradiation and medium pH alteration

In this work, the azobenzene group-containing carboxylic acid salt azobenzene-4,4′-dicarboxylate disodium salt (ADDS) was selected as the dopant for the controlled synthesis of nanostructured polypyrrole (PPy). By controlling the cis-trans configuration of ADDS (via ultraviolet light irradiation) as well as the concentration of divalent ADDS anion (via the medium pH alteration), a series of ADDS-doped PPy hydrogels with different morphologies and electrical properties were prepared accordingly. Under weak alkaline conditions (pH = 8.0), the morphology of the resulting PPy changes from nanofiber (nanobelt) to nanoflake and then to granular structure when the exposure time of ADDS aqueous solution to the UV-light irradiation was extended step by step from 0 to 15 min. This phenomenon is mainly due to the gradual decrease of the trans isomers in ADDS aqueous solution. Under visible light conditions, the morphology of the resulting PPy transforms from nanofiber (nanobelt) to granular structure when the pH of ADDS aqueous solution was varied from pH 8.0 to pH 3.0. This phenomenon is mainly due to the gradual decrease of the divalent doping anions (all trans isomers). Since trans ADDS isomers are co-planar linear molecules, and under weakly alkaline conditions, ADDS exists mainly in the form of divalent anion, the conductivity of PPy doped with all-trans ADDS (10.4 S cm-1) is therefore higher than that of PPy doped with UV-light irradiated ADDS (some trans isomers are transformed to the corresponding cis isomers) (1.0 S cm-1). It can be concluded that the morphologies and the electrical properties of ADDS-doped polypyrrole conducting hydrogels can be tuned just by varying the UV irradiation time and the medium pH, which results in the change of the steric configuration and the existing form of ADDS. The present new strategy is helpful for the controlled synthesis of conducting polymer hydrogels.

Electrosynthesized nanostructured polypyrrole on selective laser melted titanium scaffold

In this work, nanofiber polypyrrole (PPy) was electropolymerized on the three dimensional surface of SLM-Ti scaffold. The in situ measurement reveals that the potential variation within the 6.2 mm thickness porous SLM-Ti sample is about 20 mV resulting from the conducting property of PPy. SEM characterization shows that the diameter and thickness of PPy nanofiber fabricated at inner depth is smaller and thinner than that at the outer surface due to the lower effective overpotential and current inside porous SLM-Ti electrode. Based on the comparative electrochemical measurements, it is found that the nucleation and growth rate of PPy polymerization on 3D SLM-Ti electrode is slower than that of PPy on 2D SLM-Ti electrode. Although the nanofiber PPy film synthesized on porous scaffolds exhibits a relatively poorer reversibility and long-terms stability than that on dense sheets, there is a great potentiality to increase the electrochemical activity due to its super-high specific surface area. The work provides the fundamental perspective to study the mechanism of PPy electropolymerization on 3D SLM-Ti scaffold.

Selective Removal of Acid Fuchsin from Aqueous Solutions by Rapid Adsorption onto Polypyrrole Crosslinked Cellulose/Gelatin Hydrogels

The dispersion and macroization of nanomaterials have great potential in the development of high-efficiency adsorbents. To address organic dye pollution, two inexpensive and renewable biological resources, gelatin (Gel) and carboxymethyl cellulose (CMC), were crosslinked by nanostructured polypyrrole (PPy) to achieve a novel PPy-hydrogel. The morphology and composition of the CMC/Gel/PPy hydrogels were characterized. The result shows that the CMC/Gel solution can provide an excellent condition for the dispersion of polypyrrole (PPy). Based on the combination of PPy and the biomass matrix, specific adsorption sites can be formed by the synergistic effect of the functional groups derived from CMC, Gel and PPy. The CMC/Gel/PPy hydrogel has an exclusive adsorption of acid fuchsin (AF). Furthermore, the adsorption process of AF on the CMC/Gel/PPy hydrogel was investigated, and influencing factors, such as adsorbent dosage, temperature, initial dye concentration and adsorbent recyclability, were discussed in detail. Under optimal conditions, the CMC/Gel/PPy hydrogel can reach an adsorption equilibrium within 50 minutes in a 60 mg/L AF solution at 24 °C, and the AF removal efficiency was approximately 94%. It was also observed that the AF removal efficiencies of CMC/Gel/PPy remained almost unchanged after at least seven consecutive adsorption–desorption cycles.

Tunable Three-Dimensional Nanostructured Conductive Polymer Hydrogels for Energy-Storage Applications.

Three-dimensional (3D) nanostructured conducting polymer hydrogels represent a group of high-performance electrochemical energy-storage materials. Here, we demonstrate a molecular self-assembly approach toward controlled synthesis of nanostructured polypyrrole (PPy) conducting hydrogels, which was "cross-linked" by a conjugated dopant molecule trypan blue (TB) to form a 3D network with controlled morphology. The protonated TB by ion bonding aligns the free sulfonic acid groups into a certain spatial structure. The sulfonic acid group and the PPy chain are arranged by a self-sorting mechanism to form a PPy nanofiber structure by electrostatic interaction and hydrogen bonding. It is found that PPy hydrogels doped with varying dopant concentrations and changing dopant molecules exhibited controllable morphology and tunable electrochemical properties. In addition, the conjugated TB dopants promoted interchain charge transport, resulting in higher electrical conductivity (3.3 S/cm) and pseudocapacitance for the TB-doped PPy, compared with PPy synthesized without TB. When used as supercapacitor electrodes, the TB-doped PPy hydrogel reaches maximal specific capacitance of 649 F/g at the current density 1 A/g. The result shows that PPy nanostructured hydrogels can be tuned for potential applications in next-generation energy-storage materials.

Biosurfactant tailored synthesis of porous polypyrrole nanostructures: A facile approach towards CO2 adsorption and dopamine sensing

Nanostructured conducting polymers are known to function as electroactive materials in sensor devices for adsorption and detection of different analytes. For the purpose of dopamine (DA) detection and CO2 gas adsorption we have prepared nanostructured polypyrrole (PPY) with the help of sodium cholate as surfactant. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) analyses and Brunauer–Emmett–Teller (BET) measurement have been done for the characterization of nanostructure and morphology of the prepared PPY. From the sorption measurement, it is observed that the rodlike PPY structures show highest N2 uptake (91.6 mL g−1) along with appreciable surface area (85.81 m2/g) and porosity (2.53 and 4.51 nm) values. It is also observed that the maximum uptake of CO2 is 173.885 mL g−1 at 195K for the PPY synthesized without any surfactant. Electrochemical characterization of PPY modified glassy carbon electrode (GCE) was done with impedance and cyclic voltammetry experiments. DA sensing in presence of ascorbic acid, uric acid and glucose was done by LSV technique. The PPY modified electrode exhibits sensitivity values of 0.301 and 0.19 μA μM−1 cm2 over two ranges of detection limits of 0.09–0.56 and 10–50 μM for dopamine, respectively (signal/noise = 3).

Evaluation of polypyrrole/silver/polyethylene glycol nanocomposite sorbent for electroenhanced direct-immersion solid-phase microextraction of carvacrol and thymol from medicinal plants

The unique features of nanostructured polypyrrole, conductivity enhancement effect of silver nanoparticles and high polar adsorptivity of polyethylene glycol were merged into polypyrrole/silver/polyethylene glycol (PPy/Ag/PEG) nanocomposite. It was synthesized and simultaneously coated on the surface of a stainless-steel fiber using an amended electropolymerization procedure. Before coating, the fiber substrate was made porous and sticky by allocating platinum dots on the surface of the stainless-steel fiber using the electrophoretic method. The prepared fiber was applied for the extraction of carvacrol and thymol (the most important antioxidants in medicinal plants) through an electroenhanced direct-immersion solid-phase microextraction (EE-DI-SPME) sampling strategy, followed by GC-FID quantification. To achieve the best efficiency, the effectual experimental variables including pH of sample solution, applied voltage, extraction temperature and time, stirring rate, and ionic strength were investigated. Under the optimal experimental conditions, the calibration curves were linear over the range of 0.5–30 µg mL−1 for thymol and 0.01–30 µg mL−1 for carvacrol. The detection limits (3Sb) and relative standard deviation (RSD%, n = 6) were obtained to be 0.15, 0.003 µg mL−1 and 10.2, 8.7% for thymol and carvacrol, respectively. The results demonstrated the priority of the proposed fiber compared with polypyrrole and polyacrylate fibers, in terms of extraction efficiency, durability and stability. The developed method was successfully employed for the analysis of thymol and carvacrol in medicinal plants.

Wearable supercapacitors based on conductive cotton yarns

High-performance fiber- and yarn-shaped supercapacitors based on commonly available fiber materials and production technologies are needed to meet the fast developing electronic textile market. In this investigation, natural cotton and stainless steel fibers (SSFs) are blended to form a conductive yarn for constructing novel high-performance two-ply yarn supercapacitors. The supercapacitors show very high areal capacitance, energy density, flexibility and electrochemical stability. The excellent performance is attributed to the high porosity, high conductivity and distributive metal fiber network formed in the blended yarn, coupled with the high electrochemical efficiency of the nanostructured polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS) pseudocapacitance materials. The SSF-cotton blended yarn is economic to produce and retains the flexibility of a normal cotton yarn that is commonly used in apparel textiles. This greatly facilitates the integration of the two-ply yarn supercapacitor into electronic textiles.