Recent advances in food waste-derived nanoporous carbon for energy storage

Affordable and environmentally friendly electrochemically active raw energy storage materials are in high demand to switch to mass-scale renewable energy. One particularly promising avenue is the feasibility of utilizing food waste-derived nanoporous carbon. This material holds significance due to its widespread availability, affordability, ease of processing, and, notably, its cost-free nature. Over the years, various strategies have been developed to convert different food wastes into nanoporous carbon materials with enhanced electrochemical properties. The electrochemical performance of these materials is influenced by both intrinsic factors, such as the composition of elements derived from the original food sources and recipes, and extrinsic factors, including the conditions during pyrolysis and activation. While current efforts are dedicated to optimizing process parameters to achieve superior performance in electrochemical energy storage devices, it is timely to take stock of the current state of research in this emerging field. This review provides a comprehensive overview of recent developments in the fabrication and surface characterisation of porous carbons from different food wastes. A special focus is given on the applications of these food waste derived porous carbons for energy storage applications including batteries and supercapacitors.

From waste to energy storage: post-consumer waste expanded polystyrene/rGO composite as a high performance self-standing electrode for coin cell supercapacitors

This research work aims to explore the potential usage of post-consumer waste expanded polystyrene (EPS) for the fabrication of self-standing electrodes by incorporating reduced graphene oxide (rGO) into it via a facile cost-effective mechanical mixing process. The π-π interaction between the expanded polystyrene and rGO is evidenced from FT-IR and Raman analysis. The elevated thermal stability of the EPS/rGO composite from thermogravimetric analysis (TGA) further confirms the interconnection between the rGO and EPS. This π-π stacking interaction between the rGO and the polystyrene molecules present in the polymer matrix enable the composite material to be interconnected throughout which is beneficial for the charge transport process. The symmetric coin cell supercapacitor fabricated using the EPS/rGO composite electrode can be operated with a high operating voltage of 1.6 V in aqueous KOH and Na2SO4 electrolytes. The devices fabricated with KOH and Na2SO4 electrolytes deliver an areal capacitance of 11.9 mF cm-2 and 10 mF cm-2 at the discharge current density of 0.1 mA cm-2. Further, the devices fabricated with the KOH and Na2SO4 electrolytes demonstrated remarkable rate capability of 87.1% and 99.5% after 10 000 continuous charge discharge cycles. This facile method of preparation without consuming energy or polluting the environment is a novel approach which can be scaled-up to large-scale fabrication of self-standing plastic electrodes for low-cost energy storage applications.

Effect of Annealing Temperature on the Structural and Electrochemical Properties of Hydrothermally Synthesized NiCo2O4 Electrodes

In this study, a porous Ni-foam support was employed to enhance the capacitance of nickel cobaltite (NiCo2O4) electrodes designed for supercapacitors. The hydrothermal synthesis method was employed to grow NiCo2O4 as an active material on Ni-foam. The NiCo2O4 sample derived from hydrothermal synthesis underwent subsequent post-heat treatment at temperatures of 250 °C, 300 °C, and 350 °C. Thermogravimetric analysis of the NiCo2O4 showed that weight loss due to water evaporation occurs after 100 °C and enters the stabilization phase at temperatures above 400 °C. The XRD pattern indicated that NiCo2O4 grew into a spinel structure, and the TEM results demonstrated that the diffraction spots (DSs) on the (111) plane of the sample annealed at 350 °C were more pronounced than those of other samples. The specific capacitance of the NiCo2O4 electrodes exhibited a decrease with increasing current density across all samples, irrespective of the annealing temperature. The electrode annealed at 350 °C recorded the highest specific capacitance value. However, the capacity retention rate of the NiCo2O4 electrode revealed a deteriorating trend, declining to 88% at 250 °C, 75% at 300 °C, and 63% at 350 °C, as the annealing temperature increased.

Insight into the Role of Conductive Polypyrrole Coated on Rice Husk-Derived Nanosilica-Reduced Graphene Oxide as the Anodes: Electrochemical Improvement in Sustainable Lithium-Ion Batteries

Polypyrrole (PPy) is a type of conducting polymer that has garnered attention as a potential electrode material for sustainable energy storage devices. This is mostly attributed to its mechanical flexibility, ease of processing, and ecologically friendly nature. Here, a polypyrrole-coated rice husk-derived nanosilica-reduced graphene oxide nanocomposite (SiO2-rGO@PPy) as an anode material was developed by a simple composite technique followed by an in situ polymerization process. The architecture of reduced graphene oxide offers a larger electrode/electrolyte interface to promote charge-transfer reactions and provides sufficient space to buffer a large volume expansion of SiO2, maintaining the mechanical integrity of the overall electrode during the lithiation/delithiation process. Moreover, the conducting polymer coating not only improves the capacity of SiO2, but also suppresses the volume expansion and rapid capacity fading caused by serious pulverization. The present anode material shows a remarkable specific reversible capacity of 523 mAh g-1 at 100 mA g-1 current density and exhibits exceptional discharge rate capability. The cycling stability at a current density of 100 mA g-1 shows 81.6% capacity retention and high Coulombic efficiency after 250 charge-discharge cycles. The study also pointed out that this method might be able to be used on a large scale in the lithium-ion battery industry, which could have a big effect on its long-term viability. Creating sustainable nanocomposites is an exciting area of research that could help solve some of the biggest problems with lithium-ion batteries, like how easy they are to make and how big they can be used in industry. This is because they are sustainable and have less of an impact on the environment.

Molybdenum disulfide (MoS2) along with graphene nanoplatelets (GNPs) utilized to enhance the capacitance of conducting polymers (PANI and PPy)

Hybrid composites of molybdenum disulfide (MoS2), graphene nanoplatelets (GNPs) and polyaniline (PANI)/polypyrrole (PPy) have been synthesized as cost-effective electrode materials for supercapacitors. We have produced MoS2 from molybdenum dithiocarbamate by a melt method in an inert environment and then used a liquid exfoliation method to form its composite with graphene nanoplatelets (GNPs) and polymers (PANI and PPy). The MoS2 melt/GNP ratio in the resultant composites was 1 : 3 and the polymer was 10% by wt. of the original composite. XRD (X-ray diffraction analysis) confirmed the formation of MoS2 and SEM (scanning electron microscopy) revealed the morphology of the synthesized materials. The electrochemical charge storage performance of the synthesized composite materials was assessed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge (GCCD) measurements. Resultant composites showed enhanced electrochemical performances (specific capacitance = 236.23 F g-1, energy density = 64.31 W h kg-1 and power density = 3858.42 W kg-1 for MoS2 melt 5 mPP at a current density of 0.57 A g-1 and had 91.87% capacitance retention after 10 000 charge-discharge cycles) as compared to the produced MoS2; thus, they can be utilized as electrode materials for supercapacitors.

Nanostructured Conducting Polymers and Their Applications in Energy Storage Devices

Due to the energy requirements for various human activities, and the need for a substantial change in the energy matrix, it is important to research and design new materials that allow the availability of appropriate technologies. In this sense, together with proposals that advocate a reduction in the conversion, storage, and feeding of clean energies, such as fuel cells and electrochemical capacitors energy consumption, there is an approach that is based on the development of better applications for and batteries. An alternative to commonly used inorganic materials is conducting polymers (CP). Strategies based on the formation of composite materials and nanostructures allow outstanding performances in electrochemical energy storage devices such as those mentioned. Particularly, the nanostructuring of CP stands out because, in the last two decades, there has been an important evolution in the design of various types of nanostructures, with a strong focus on their synergistic combination with other types of materials. This bibliographic compilation reviews state of the art in this area, with a special focus on how nanostructured CP would contribute to the search for new materials for the development of energy storage devices, based mainly on the morphology they present and on their versatility to be combined with other materials, which allows notable improvements in aspects such as reduction in ionic diffusion trajectories and electronic transport, optimization of spaces for ion penetration, a greater number of electrochemically active sites and better stability in charge/discharge cycles.

Mechanochemical Synthesis of Polyanilines and Their Nanocomposites: A Critical Review

The mechanochemical synthesis of polyanilines (PANIs), made by oxidative polymerization of anilines, is reviewed. First, previous knowledge of the polymerization reaction in solution is discussed to understand the effect of different parameters: oxidant/monomer ratio, added acid, oxidant, temperature and water content on the properties of the conducting polymers (molecular weight, degradation, doping/oxidation level, conductivity, and nanostructure). The work on mechanochemical polymerization (MCP) of anilines is analyzed in view of previous data in solution, and published data are critically reconsidered to clarify the interpretation of experimental results. A key factor is the production of acids during polymerization, which is often overlooked. The production of gaseous HCl during MCP of aniline hydrochloride is experimentally observed. Since some experiments involves the addition of small amounts of water, the kinetics and heat balance of the reaction with concentrated solutions were simulated. A simple experiment shows fast (<2 min) heating of the reaction mixture to the boiling point of water and temperature increments are observed during MCP in a mortar. The form and sizes of PANI nanostructures made by MCP or solution are compared. The extensive work on the production of nanocomposites by MCP of anilines together with different nanomaterials (porous clays, graphene, carbon nanotubes, metal, and oxide nanoparticles) is also described.

Group 16 conjugated polymers based on furan, thiophene, selenophene, and tellurophene

Five-membered aromatic rings containing Group 16 elements (O, S, Se, and Te), also referred as chalcogenophenes, are ubiquitous building blocks for π-conjugated polymers (CPs). Among these, polythiophenes have been established as a model system to study the interplay between molecular structure, solid-state organization, and electronic performance. The judicious substitution of alternative heteroatoms into polythiophenes is a promising strategy for tuning their properties and improving the performance of derived organic electronic devices, thus leading to the recent abundance of CPs containing furan, selenophene, and tellurophene. In this review, we first discuss the current status of Kumada, Negishi, Murahashi, Suzuki-Miyaura, and direct arylation polymerizations, representing the best routes to access well-defined chalcogenophene-containing homopolymers and copolymers. The self-assembly, optical, solid-state, and electronic properties of these polymers and their influence on device performance are then summarized. In addition, we highlight post-polymerization modifications as effective methods to transform polychalcogenophene backbones or side chains in ways that are unobtainable by direct polymerization. Finally, the major challenges and future outlook in this field are presented.

Polyaniline inside the pores of high surface area mesoporous silicon as composite electrode material for supercapacitors

Mesoporous silicon (mSi) obtained by the magnesiothermic reduction of mesoporous silica was used to deposit polyaniline (PANI) in its pores, the composite was tested for its charge storage application for high performance supercapacitor electrodes. The mesoporous silica as confirmed by Small Angle X-ray Scattering (SAXS) has a Brunauer–Emmett–Teller (BET) surface area of 724 m²g⁻¹ and mean pore size of 5 nm. After magnesiothermic reduction to mSi, the BET surface area is reduced to 348 m²g⁻¹ but the mesoporousity is retained with a mean pore size of 10 nm. The BET surface area of mesoporous silicon is among the highest for porous silicon prepared/reduced from silica. In situ polymerization of PANI inside the pores of mSi was achieved by controlling the polymerization conditions. As a supercapacitor electrode, the mSi–PANI composite exhibits better charge storage performance as compared to pure PANI and mesoporous silica–PANI composite electrodes. Enhanced electrochemical performance of the mSi–PANI composite is attributed to the high surface mesoporous morphology of mSi with a network structure containing abundant mesopores enwrapped by an electrochemically permeable polyaniline matrix.

Magnesiothermic reduction was used to reduce mesoporous silica to mesoporous silicon which can host a variety of materials such as polyaniline and has potential to be used in supercapacitors.

Revised Manuscript with Corrections: Polyurethane-Based Conductive Composites: From Synthesis to Applications

The purpose of this review article is to outline the extended applications of polyurethane (PU)-based nanocomposites incorporated with conductive polymeric particles as well as to condense an outline on the chemistry and fabrication of polyurethanes (PUs). Additionally, we discuss related research trends of PU-based conducting materials for EMI shielding, sensors, coating, films, and foams, in particular those from the past 10 years. PU is generally an electrical insulator and behaves as a dielectric material. The electrical conductivity of PU is imparted by the addition of metal nanoparticles, and increases with the enhancing aspect ratio and ordering in structure, as happens in the case of conducting polymer fibrils or reduced graphene oxide (rGO). Nanocomposites with good electrical conductivity exhibit noticeable changes based on the remarkable electric properties of nanomaterials such as graphene, RGO, and multi-walled carbon nanotubes (MWCNTs). Recently, conducting polymers, including PANI, PPY, PTh, and their derivatives, have been popularly engaged as incorporated fillers into PU substrates. This review also discusses additional challenges and future-oriented perspectives combined with here-and-now practicableness.

Conjugated Molecules and Polymers in Secondary Batteries: A Perspective

Intrinsically conducting polymers constituting a subclass of macromolecules, as well as a still growing family of large, conjugated molecules, oligomers, and polymers, have attracted research interest for the recent decades. Closely corresponding to the fascination of these materials, combining typical properties of organic polymers and metallic materials, numerous applications have been suggested, explored, and sometimes transferred into products. In electrochemistry, they have been used in various functions beyond the initially proposed and obvious application as active masses in devices for electrochemical energy conversion and storage. This perspective contribution wraps up basic facts that are necessary to understand the behavior and properties of the oligo and polymers and their behavior in electrochemical cells for energy conversion by electrode reactions and associated energy storage. Representative examples are presented and discussed, and an overview of the state of research and development is provided. Particular attention is paid to stability and related aspects of practical importance. Future trends and perspectives are indicated.

Nanoarchitectured Porous Conducting Polymers: From Controlled Synthesis to Advanced Applications

Conductive polymers (CPs) integrate the inherent characteristics of conventional polymers and the unique electrical properties of metals. They have aroused tremendous interest over the last decade owing to their high conductivity, robust and flexible properties, facile fabrication, and cost-effectiveness. Compared to bulk CPs, porous CPs with well-defined nano- or microstructures possess open porous architectures, high specific surface areas, more exposed reactive sites, and remarkably enhanced activities. These attractive features have led to their applications in sensors, energy storage and conversion devices, biomedical devices, and so on. In this review article, the different strategies for synthesizing porous CPs, including template-free and template-based methods, are summarized, and the importance of tuning the morphology and pore structure of porous CPs to optimize their functional performance is highlighted. Moreover, their representative applications (energy storage devices, sensors, biomedical devices, etc.) are also discussed. The review is concluded by discussing the current challenges and future development trend in this field.

Preparation of a polymer nanocomposite via the polymerization of pyrrole : biphenyldisulfonic acid : pyrrole as a two-monomer-connected precursor on MoS2 for electrochemical energy storage

We prepared a poly(pyrrole : biphenyldisulfonic acid : pyrrole (Py:BPDSA:Py)) nanocomposite of molybdenum disulfide (MoS₂), P(Py:BPDSA:Py)-MoS₂, with high crystallinity. The composite is synthesized by oxidative polymerization of Py:BPDSA:Py as a two-monomer-connected precursor (TMCP) linked by ionic bonding on a molybdenum disulfide (MoS₂) monolayer. The chemical, structural and morphological characterization of this composite is confirmed by Raman spectroscopy, FT-IR, X-ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy (EELS), and scanning electron microscopy (SEM). The crystal structure is analysed by X-ray diffraction (XRD) and high-voltage electron microscopy (HVEM), which shows a face-centered cubic (FCC) crystal structure for the composite. Nitrogen adsorption-desorption isotherms show an improved specific surface area (91.3 m² g^-1). The electrochemical properties of the composite with a unique crystal structure and a large specific surface area are analysed through cyclic voltammetry (CV), which shows a specific capacitance of 681 F g^-1 demonstrating that the composite can be used as an efficient electrode active material for electrochemical energy storage systems.

A comprehensive review on the photocatalytic activity of polythiophene-based nanocomposites against degradation of organic pollutants

Photocatalytic activity of polythiophene-based nanocomposites.

Polytriphenylamine composites for energy storage electrodes: effect of pendant vs. backbone polymer architecture of the electroactive group

Polymers are an increasingly used class of materials in semiconductors, photovoltaics and energy storage. Polymers bearing triphenylamine (TPA) or its derivatives in their structures have shown promise for application in electrochemical energy storage devices. The aim of this work is to systematically synthesize polymers bearing TPA units either as pendant groups or directly along the backbone of the polymer and evaluate their performance as electrochemical energy storage electrode materials. The first was obtained via radical polymerization of an acrylate monomer bearing TPA as a side group, resulting in a non-conjugated polymer with individual redox active sites (rP). The latter was obtained by oxidative polymerization of a substituted TPA, resulting in a conjugated polymer with TPA units along its backbone (cP). These polymers were then developed into electrodes by separately blending them with multi-wall carbon nanotubes (rC and cC). The electrodes were characterized and their charge storage stability and mechanical properties were investigated for up to 1000 cycles by cyclic voltammetry, galvanostatic charge–discharge measurements and nanoindentation. The results show that cC offers a higher initial charge capacity than rC as well as improved carbon nanotube dispersion due to its conjugated structure. Although the improved dispersion results in a higher elastic modulus for cC (compared to rC), the stiffer nature of cP made it more vulnerable to degrade upon repetitive volumetric change, while with rP, the decoupled acrylate monomer remained more protected when its redox active units of TPA underwent charge–discharge cycling.

Interaction between (a) CNT-rP-CNT with CNTs sliding next to each other, (b) CNT-cP-CNT with CNTs repulsed via steric hinderance.

A Review of Battery Materials as CDI Electrodes for Desalination

The world is suffering from chronic water shortage due to the increasing population, water pollution and industrialization. Desalinating saline water offers a rational choice to produce fresh water thus resolving the crisis. Among various kinds of desalination technologies, capacitive deionization (CDI) is of significant potential owing to the facile process, low energy consumption, mild working conditions, easy regeneration, low cost and the absence of secondary pollution. The electrode material is an essential component for desalination performance. The most used electrode material is carbon-based material, which suffers from low desalination capacity (under 15 mg·g−1). However, the desalination of saline water with the CDI method is usually the charging process of a battery or supercapacitor. The electrochemical capacity of battery electrode material is relatively high because of the larger scale of charge transfer due to the redox reaction, thus leading to a larger desalination capacity in the CDI system. A variety of battery materials have been developed due to the urgent demand for energy storage, which increases the choices of CDI electrode materials largely. Sodium-ion battery materials, lithium-ion battery materials, chloride-ion battery materials, conducting polymers, radical polymers, and flow battery electrode materials have appeared in the literature of CDI research, many of which enhanced the deionization performances of CDI, revealing a bright future of integrating battery materials with CDI technology.

Synthesis of Polypyrrole/Reduced Graphene Oxide Hybrids via Hydrothermal Treatment for Energy Storage Applications

Herein, we propose hydrothermal treatment as a facile and environmentally friendly approach for the synthesis of polypyrrole/reduced graphene oxide hybrids. A series of self-assembled hybrid materials with different component mass ratios of conductive polymer to graphene oxide was prepared. The morphology, porous structure, chemical composition and electrochemical performance of the synthesized hybrids as electrode materials for supercapacitors were investigated. Nitrogen sorption analysis at 77 K revealed significant changes in the textural development of the synthesized materials, presenting specific surface areas ranging from 25 to 199 m² g^-1. The combination of the pseudocapacitive polypyrrole and robust graphene material resulted in hybrids with excellent electrochemical properties, which achieved specific capacitances as high as 198 F g^-1 at a current density of 20 A g^-1 and retained up to 92% of their initial capacitance after 3000 charge-discharge cycles. We found that a suitable morphology and chemical composition are key factors that determine the electrochemical properties of polypyrrole/reduced graphene oxide hybrid materials.

Cyclic versus straight chain oligofuran as sensor: A detailed DFT study

This study presents a novel approach for exploring the sensitivity and selectivity of cyclic oligofuran (5/6/7CF) toward gaseous analytes and their comparison with straight chain analogues (5/6/7SF). The work is not only vital to understand the superior sensitivity but also for rational design of new sensors based on cyclic ring structures of oligofuran. Interaction of cyclic and straight chain oligofuran with NH₃, CO, CO₂, N₂H₄, HCN, H₂O₂, H₂S, CH₄, CH₃OH, SO₂, SO₃ and H₂O analytes is studied via DFT calculation at B3LYP-D3/6-31++G (d, p) level of theory. The sensitivity and selectivity are illustrated by the thermodynamic parameters (E_bind, SAPT0 energies, NCI analysis), electronic properties (H-L gap, percentage of average energy gap, CHELPG charge transfer, DOS spectra), and UV-Vis analysis. All these properties are simulated at B3LYP/6-31G (d) level of theory while UV-Vis is calculated at TD-DFT method. Cyclic oligofurans have high binding energies with analytes compared to 5/6/7SF which corresponds to higher sensitivity of 5/6/7CF. Furthermore, the cyclization of oligofuran significantly improves the sensitivity and selectivity of the system. Alteration in electronic properties of 5/6/7CF and 5/6/7SF is remarkably high upon complexation with SO₂ and SO₃. Further the stability of rings (5, 6 and 7 membered cyclic oligofurans) and their SO₃ complexes is also confirmed by molecular dynamics calculations. The findings of the work clearly suggest that the cyclic geometry enhances not only sensitivity but also selectivity of conducting polymers (oligofuran).

Electron Transfer Kinetics at Graphene Quantum Dot Assembly Electrodes

Electrochemical performance of nanostructured carbon electrodes was evaluated using cyclic voltammetry and a simple simulation model. The electrodes were prepared from soluble precursors by anodic electrodeposition of two sizes of graphene quantum dot assemblies (hexabenzocoronene (HBC) and carbon quantum dot (CQD)) onto a conductive support. Experimental and simulated voltammograms enabled the extraction of the following electrode parameters: conductivity of the electrodes (a combination of ionic and electronic contributions), density of available electrode states at different potentials, and tunneling rate constant (Marcus-Gerischer model) for interfacial charge transfer to ferrocene/ferrocenium (Fc/Fc⁺) couple. The parameters indicate that HBC and CQD have significant density of electronic states at potentials more positive than -0.5 V versus Ag/Ag⁺. Enabled by these large densities, the electron transfer rates at the Fc/Fc⁺ thermodynamic potential are several orders of magnitude slower than those commonly observed on other carbon electrodes. This study is expected to accelerate the discovery of improved synthetic carbon electrodes by providing fast screening methodology of their electrochemical behavior.

Growth of close-packed crystalline polypyrrole on graphene oxide via in situ polymerization of two-monomer-connected precursors

Synthesis of a two-dimensional (2D) highly crystalline composite, P(Py:BPDSA:Py)-GO, from the growth of a close-packed polymer crystal, P(Py:BPDSA:Py), on graphene oxide (GO) sheets via in situ polymerization of two-monomer-connected precursors (TMCPs, Py:BPDSA:Py), in which two pyrrole (Py) molecules are linked through a connector (4,4'-biphenyldisulfonic acid) (BPDSA), is reported. When the TMCP is polymerized on GO, it leads to an exceptionally ordered structure determined by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) studies. X-ray crystallography of the composite shows crystalline peaks with d spacings in the [100] direction. Transmission electron microscopy (TEM) analysis indicates that the composite has a face-centered cubic (FCC) crystal structure. Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) show that this composite with a well-defined nanostructure was successfully synthesized. Nitrogen adsorption-desorption isotherms show that this composite, P(Py:BPDSA:Py)-GO, has an improved specific surface area (71 m² g^-1) compared to that of P(Py:BPDSA:Py) (3.1 m² g^-1). The electrochemical properties of the composite studied by cyclic voltammetry indicates a specific capacitance of 480 F g^-1 without an additional conducting material such as carbon black, suggesting its use as a pseudocapacitor.

Highly sensitive polyaniline-coated fiber gas sensors for real-time monitoring of ammonia gas

A single-yarn-based gas sensor has been made from conductive polyaniline coated on commercial yarns. This can detect ammonia gas concentration in an environment or a working area. Cotton, rayon and polyester are utilized as substrates using a dip-coating process. The conductive yarns show ohmic behavior with an electrical resistance of 15-31 kΩ cm-1. The conductive polyester yarn exhibits higher mechanical strength even after intensive chemical treatment. It also has the highest gas response of 57% of 50 ppm ammonia gas, the concentration at which health problems will occur. A linear gas response of the yarn sensor appears in a range of 5-25 ppm ammonia concentration. The polyester yarn sensor can be reused without any change in its sensing response. It can monitor gas levels continuously giving real-time results. By using a microcontroller as part of the circuitry, the gas detection results are transferred and updated wirelessly to a computer or to a smartphone. The textile-based gas sensor can be sewn directly onto the fabrics since it is made with the same fabric. This single-yarn-based gas sensor is suitable for mass production and is appropriate for sophisticated applications.

Extended 2,2'-Bipyrroles: New Monomers for Conjugated Polymers with Tailored Processability

The synthesis of 2,2′-bipyrroles substituted at positions 5,5′ with pyrrolyl, N-methyl-pyrrolyl and thienyl groups and their application in the preparation of conducting polymers is reported herein. The preparation of these monomers consisted of two synthetic steps from a functionalized 2,2′-bipyrrole: Bromination of the corresponding 2,2′-bipyrrole followed by Suzuki or Stille couplings. These monomers display low oxidation potential compared to pyrrole because of the extended length of their conjugation pathway. The resulting monomers can be polymerized through oxidative/electropolymerization. Electrical conductivity and electrochromic properties of the electrodeposited polymeric films were evaluated using 4-point probe measurements and cyclic voltammetry to evaluate their applicability in electronics.

Tailoring Characteristics of PEDOT:PSS Coated on Glass and Plastics by Ultrasonic Substrate Vibration Post Treatment

In this work, we excited as-spun wet films of PEDOT:PSS by ultrasonic vibration with varying frequency and power. This is a low-cost and facile technique for tailoring the structural and surface characteristics of solution-processed thin films and coatings. We deposited the coatings on both rigid and flexible substrates and performed various characterization techniques, such as atomic force microscopy (AFM), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), transmittance, electrical conductivity, and contact angle measurements, to understand how the ultrasonic vibration affects the coating properties. We found that as a result of ultrasonic vibration, PEDOT:PSS sheet conductivity increases up to five-fold, contact angle of water on PEDOT:PSS increases up to three-fold, and PEDOT:PSS roughness on glass substrates substantially decreases. Our results affirm that ultrasonic vibration can favor phase separation of PEDOT and PSS and rearrangement of PEDOT-rich charge transferring grains. In addition to providing a systematic study on the effect of ultrasonic frequency and power on the film properties, this work also proves that the ultrasonic vibration is a novel method to manipulate and tailor a wide range of properties of solution-processed thin films, such as compactness, chain length and arrangement of polymer molecules, conductivity, and surface wettability. This ultrasonication method can serve organic, printed and flexible electronics.

Amphiphilic polypyrrole-poly(Schiff base) copolymers with poly(ethylene glycol) side chains: synthesis, properties and applications

New amphiphilic poly(ethylene glycol) (PEG)-grafted random intrinsically conducting copolymers which combine three different functionalities have been engineered, prepared and characterized.

Condensing Vapor Phase Polymerization (CVPP) of Electrochemically Capacitive and Stable Polypyrrole Microtubes

We introduce a novel condensing vapor phase polymerization (CVPP) strategy for depositing microtubes of the conducting polymer polypyrrole; these serve as one-dimensional hollow microstructures for storing electrochemical energy. In CVPP, water droplets are structure-directing templates for polypyrrole microtubes. Water vapor condensation and polymerization occur simultaneously-conformal coatings of microtubes deposit on porous substrates such as hard carbon fiber paper or glass fiber filter paper. A mechanistic evolution of the microtubular morphology is proposed and tested based on the mass transport of water and monomer vapors as well as on the reaction stoichiometry. A coating of PPy microtubes is characterized by a high reversible capacitance of 342 F g^-1 at 5 mV s^-1 throughout 5000 cycles of cyclic voltammetry and a low sheet resistance of 70.2 Ω □^-1. The open tubular structure is controlled in situ during synthesis and leads to electrodes that exhibit electrochemical stability at high scanning rates up to 250 mV s^-1 retaining all stored charge, even after extensive cycling at 25 mV s^-1.