Conducting Polymer-Based Catalysts

Chemically synthesized poly(3,4-ethylenedioxythiophene) conducting polymer as a robust electrocatalyst for highly efficient dye-sensitized solar cells

Chemically synthesized PEDOT (poly(3,4-ethylenedioxythiophene)) nanomaterials, with various nanostructured morphologies as well as different intrinsic electrical conductivities and crystallinities, were compared as electrocatalysts for Co(III) reduction in dye-sensitized solar cells (DSSCs). Electrochemical parameters, charge transfer resistance toward the electrode/electrolyte interface, catalytic activity for Co(III)-reduction, and diffusion of cobalt redox species greatly depend on the morphology, crystallinity, and intrinsic electrical conductivity of the chemically synthesized PEDOTs and optimization of the fabrication procedure for counter electrodes. The PEDOT counter electrode, fabricated by spin coating a DMSO-dispersed PEDOT solution with an ordered 1D structure and nanosized fibers averaging 70 nm in diameter and an electrical conductivity of ∼16 S cm-1, exhibits the lowest charge transfer resistance, highest diffusion for a cobalt redox mediator and superior electrocatalytic performance compared to a traditional Pt-counter electrode. The photovoltaic performance of the DSSC using chemically synthesized PEDOT exceeds that of a Pt-electrode device because of the enhanced current density, which is directly related to the superior electrocatalytic ability of PEDOT for Co(III)-reduction. This simple spin-coated counter electrode prepared using cheap and scalable chemically synthesized PEDOT can be a potential alternative to the expensive Pt-counter electrode for cobalt and other redox electrolytes in DSSCs and various flexible electronic devices.

P3MOT-decorated metal-porphyrin-based zirconium-MOF for the efficient electrochemical detection of 4-nitrobenzaldehyde

A novel hybrid composite integrating conductive poly-3-methoxythiophene and PCN-222(Fe) (porphyrin-metal-organic frameworks) was synthesized using an in situ polymerization strategy. Leveraging the large specific area of MOFs and the low electrical resistance of conductive polymers, the modified electrode proved to be a promising candidate for the electrochemical detection of 4-nitrobenzaldehyde. The electrocatalytic response was measured using differential pulse voltammetry techniques and cyclic voltammetry, where the linear concentration range of analyte detection was estimated to be 0-900 μM and the detection limit was 0.233 μM with high selectivity toward the analyte. The sensor demonstrated repeatability and stability, allowing the direct electroanalytical measurement of 4-nitrobenzaldehyde in real samples with reliable recovery. This methodology expands the application of porphyrin MOFs for the electroanalytical sensing of environmental contaminants.

Self-Healing Conjugated Microporous Polyanilines for Effective and Continuous Catalytic Detoxification of 4-Nitrophenol to 4-Aminophenol

Detoxification of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with high efficiency and dynamic performance is challenging for a polymeric catalyst. Herein, a series of conjugated microporous polyanilines (CMPAs), capable of efficiently catalytically reducing 4-NP, were synthesized based on the Buchwald-Hartwig cross-coupling reaction mechanism. By adjusting the types of linkers and the molar ratios of linker to core, CMPAs with different Brunauer-Emmett-Teller (BET) specific surface areas and reduction degrees were obtained and used as the catalysts in reducing 4-NP. The ultrahigh catalytic reduction efficiency (K = 141.32 s-1 g-1, kapp = 0.00353 s-1) was achieved when using CMPA-3-0.7 as the catalyst (prepared with 4,4'-diaminodiphenylamine as the linker and a 0.7:1 molar ratio of linker to core). The catalytic reduction performance exhibited a strong correlation with the reduction degree and BET specific surface area of CMPAs. Furthermore, they also exhibit excellent cycling stability and dynamic performance. The coexistence of a microporous structure and high BET specific surface area endowed CMPAs with an increased number of catalytic active centers. The reversible redox transformation of CMPAs in the presence of NaBH4 and air enabled self-healing (the oxidation units in CMPAs were reduced to reduction units by NaBH4, and the newly generated reduction unit in CMPAs was subsequently oxidized to its original state by the O2 in the air), leading to the reduction reaction of 4-NP proceeded continuously and stably. The aforementioned factors resulted in the high efficiency of CMPAs for reducing 4-NP to 4-AP, enhancing the practical application prospects of CMPAs in the detoxification of 4-NP wastewater.

Conjugated Polymer Modifying TiO2 Performance for Visible-Light Photodegradation of Organics

Up to now, the use of TiO₂ has been considered a promising advanced technology for organic pollutants removal from air or water, since it has high biological and chemical stability, high photoactivity, low toxicity, and low-cost production. However, there are issues to be addressed in enhancing TiO₂ performance, and one of the current key issues is redesigning UV-active photocatalysts and making them active in the visible region of the electromagnetic spectrum. This way, solar light absorption will be insured, and thus, a more efficient photocatalyst could be obtained. For this reason, conjugated polymers and their derivatives are considered to act as photosensitizers, being able to shift the TiO₂ activity from the UV to the visible region. Therefore, this study focuses on the synthesis of TiO₂/conjugated polymer systems, which was accomplished by the deposition of poly-3,4-ethylene-dioxy-thiophene (PEDOT [-C₆H₄O₂S-]_n), a low-band semiconductor with an excellent stability due to its extending π-conjugated electron system, on titania nanoarchitecture. First of all, a TiO₂ nanoarchitecture was synthesized by an ultrasound-assisted sol-gel method. Then, TiO₂/PEDOT systems were obtained and characterized by using different techniques such as X-ray diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, UV-Vis diffuse reflectance, and N₂ sorption measurements. The synthesized composites confirmed their mesoporosity and lower band gap values compared to bare titania, which clearly shows the ability to work as photocatalysts under visible-light activity. Further, we demonstrated that an organic pollutant, Congo Red dye, used as a model molecule could be photodegraded with the synthesized TiO₂/PEDOT systems, with efficiencies of up to 95% in the case of T_convPEDOT under UV light and up to 99% for T_convPEDOT under visible-light irradiation, accomplishing in this way a successful synthesis of visible-light-activated titania photocatalyst.

An electrochemical immunosensor based on polyaniline microtubules and zinc gallinate for detection of human growth differentiation factor-15

The incidence rate of cardiovascular diseases (CVDs) remains high, and their mortality rate is significantly higher than that of other diseases. Growth differentiation factor-15 (GDF-15) is a recently developed biomarker for the early diagnosis and prognostic evaluation of CVDs because its concentration in serum increases substantially after a cardiovascular injury or an inflammatory reaction. In this study, a sandwich-type immunosensor was constructed for the sensitive detection of GDF-15. Specifically, peony-like zinc gallinate (ZnGa₂O₄) prepared using a hydrothermal method, which exhibits excellent electrocatalytic performance, was coupled with Au nanoparticles (NPs) to obtain golden-peony-like ZnGa₂O₄/Au NPs. They preserved the immune activity of GDF-15 antibody molecules and further enhanced the conductivity, thereby realizing additional signal amplification. Hollow polyaniline (PANI) microtubules decorated with Pd NPs were used as the sensing platform (PANI/Pd NPs). The hollow microtubules provided abundant active sites and considerably improved the electron-transfer rate. Under optimal conditions, a linear range and remarkably low detection limit of 100 fg mL^-1-10 ng mL^-1 and 42.23 fg mL^-1, respectively, were achieved. These experimental results indicate that the strategy reported herein can be adopted as a novel approach for the convenient and rapid detection of GDF-15.

Conductive Polyaniline-Indium Oxide Composite Films Prepared by Sequential Infiltration Synthesis for Electrochemical Energy Storage

Composites of conductive polymers (CP) and metal oxides (MO) have attracted continued interest in the past decade for diverse application fields because the synergistic effects of CP and MO enable the realization of unusual electronic, electrochemical, catalytic, and mechanical properties of the composites. Herein, we present a novel method for the sequential infiltration synthesis of composite films of polyaniline (PANI) and indium oxide (InO _x ) with high electrical conductivities (4-9 S/cm). The synthesized composite films were composed of two phases of graded concentration: InO _x with oxygen vacancies and PANI with partially protonated molecular units. The PANI-InO _x composite films displayed enhanced electrochemical activity with a pair of well-defined redox peaks. The open interfacial regions between the InO _x and PANI phases may provide efficient pathways for ion diffusion and active sites for improved charge transfer.

Recent advancement in conjugated polymers based photocatalytic technology for air pollutants abatement: Cases of CO2, NOx, and VOCs

According to World Health Organization (WHO) survey, air pollution has become the major reason of several fatal diseases, which had led to the death of 7 million peoples around the globe. The 9 people out of 10 breathe air, which exceeds WHO recommendations. Several strategies are in practice to reduce the emission of pollutants into the air, and also strict industrial, scientific, and health recommendations to use sustainable green technologies to reduce the emission of contaminants into the air. Photocatalysis technology recently has been raised as a green technology to be in practice towards the removal of air pollutants. The scientific community has passed a long pathway to develop such technology from the material, and reactor points of view. Many classes of photoactive materials have been suggested to achieve such a target. In this context, the contribution of conjugated polymers (CPs), and their modification with some common inorganic semiconductors as novel photocatalysts, has never been addressed in literature till now for said application, and is critically evaluated in this review. As we know that CPs have unique characteristics compared to inorganic semiconductors, because of their conductivity, excellent light response, good sorption ability, better redox charge generation, and separation along with a delocalized π-electrons system. The advances in photocatalytic removal/reduction of three primary air-polluting compounds such as CO₂, NO_X, and VOCs using CPs based photocatalysts are discussed in detail. Furthermore, the synergetic effects, obtained in CPs after combining with inorganic semiconductors are also comprehensively summarized in this review. However, such a combined system, on to better charges generation and separation, may make the Adsorb & Shuttle process into action, wherein, CPs may play the sorbing area. And, we hope that, the critical discussion on the further enhancement of photoactivity and future recommendations will open the doors for up-to-date technology transfer in modern research.

Greatly increased electrical conductivity of PBTTT-C14 thin film via controllable single precursor vapor phase infiltration

Doping is an important strategy for effectively regulating the charge carrier concentration of semiconducting materials. In this study, the electronic properties of organic-inorganic hybrid semiconducting polymers, synthesized viain situcontrolled vapor phase infiltration (VPI) of poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT-C14) with the metal precursors molybdenum pentachloride (MoCl₅) and titanium tetrachloride (TiCl₄), were altered and characterized. The conductivities of the infiltration-doped PBTTT-C14 thin films were enhanced by up to 9 and 4 orders of magnitude, respectively. The significantly improved electrical properties may result from interactions between metal atoms in the metal precursors and sulfur of the thiophene rings, thus forming new chemical bonds. Importantly, VPI doping has little influence on the structure of the PBTTT-C14 thin films. Even if various dopant molecules infiltrate the polymer matrix, the interlayer spacing of the films will inevitably expand, but it has negligible effects on the overall morphology and structure of the film. Also, Lewis acid-doped PBTTT-C14 thin films exhibited excellent environmental stability. Therefore, the VPI-based doping process has great potential for use in processing high-quality conductive polymer films.

Low Platinum-Content Electrocatalysts for Highly Sensitive Detection of Endogenously Released H2O2

The commercial viability of electrochemical sensors requires high catalytic efficiency electrode materials. A sluggish reaction of the sensor’s primary target species will require a high overpotential and, consequently, an excessive load of catalyst material to be used. Therefore, it is essential to understand nanocatalysts’ fundamental structures and typical catalytic properties to choose the most efficient material according to the biosensor target species. Catalytic activities of Pt-based catalysts have been significantly improved over the decades. Thus, electrodes using platinum nanocatalysts have demonstrated high power densities, with Pt loading considerably reduced on the electrodes. The high surface-to-volume ratio, higher electron transfer rate, and the simple functionalisation process are the main reasons that transition metal NPs have gained much attention in constructing high-sensitivity sensors. This study has designed to describe and highlight the performances of the different Pt-based bimetallic nanoparticles and alloys as an enzyme-free catalytic material for the sensitive electrochemical detection of H₂O₂. The current analysis may provide a promising platform for the prospective construction of Pt-based electrodes and their affinity matrix.

Space-Confined Synthesis of Thin Polypyrrole Nanosheets in Layered Bismuth Oxychloride for a Photoresponse Antibacterial within the Near-Infrared Window and Accelerated Wound Healing

Bacterial infection greatly affects the rate of wound healing. Both photothermal and photodynamic antibacterial therapies activated by near-infrared (NIR) light with semiconductor nanomedicine are two effective approaches to address bacterial infections, but they cannot coexist synergistically to kill bacteria more efficiently because of the limitation of the band structure. Here, inspired by the natural core-shell structure and photosynthesis simultaneously, polypyrrole (PPy) is synthesized in the two-dimensional restricted area of the layered bismuth oxychloride (BiOCl) nanosheets through the in situ ultrasonic recombination method. The atomic-level interface contact and bonding formed in the PPy-BiOCl intercalated nanosheets not only improve the light-to-heat conversion capabilities of PPy but also promote the transmission of PPy photogenerated charge carriers to the BiOCl semiconductor. The nanocomposites take advantage of the deeper tissue penetration under NIR light irradiation and exhibit excellent photothermal and photodynamic synergistic antibacterial activity. In addition, PPy-BiOCl intercalated nanosheets have good biocompatibility and accelerate wound healing through their antimicrobial activity and skin repair function. The space-confined synthesis of thin PPy nanosheets in layered structures offers an efficient NIR photoresponsive nanomedicine for the treatment of pathogen infection, with promising applications in infected wound healing.

Insights to the tribe Haemantheae of the South African Amaryllidaceae

ETHNOPHARMACOLOGICAL RELEVANCE

The family Amaryllidaceae has been documented in traditional systems of medicine around the globe. Its member tribe Haemantheae occurs chiefly in South Africa, where around twenty of its species are identifiable with a wide variety of functions in such practices.

AIM OF THE STUDY

This account details work published from 2013 to 2020 on the tribe Haemantheae involving Clivia, Cryptostephanus, Haemanthus, Scadoxus and Gethyllis. Focus is maintained on the traditional medicinal aspects, pharmacological activities and identification of the active principles. Significant effort is also made to outline the molecular basis to some of these effects.

MATERIALS AND METHODS

The major search engine platforms including, SciFinder, Scopus, ScienceDirect, PubMed and Google Scholar were utilized at the literature consolidation stage. Keywords engaged in the process included 'Amaryllidaceae' and 'Haemantheae' as well as individual genera and specie names.

RESULTS

Twenty-four species of the five genera were encountered over the designated time frame. New traditional medicinal information has emerged on nine of these species, where usage ranged from the treatment of wounds and infections, circulatory and gastrointestinal issues to AIDS and TB. Significant amounts of new data also appeared in relation to the antimicrobial, anti-inflammatory, antioxidant, anticholinesterase, antidepressive and cytotoxic effects of these plants. Potent activities were observed in some instances, as they were in regards to the anti-inflammatory effects of some Gethyllis species in their cyclooxygenase-inhibitory effects. The entities behind these activities, with few exceptions, were shown to be isoquinoline alkaloids which are known to dominate the chemistry of the Amaryllidaceae. Interesting observations were also made for the mechanisms behind some of the effects, notably in the inflammatory and motorneuron disease arenas.

CONCLUSIONS

The tribe Haemantheae has proved to be a rich and diverse platform for studies of the Amaryllidaceae in the key areas of traditional medicine, pharmacology and phytochemistry. Indigenous knowledge has played a significant role in guiding the biological evaluations, while identification of the active principles has been bolstered by the exceedingly rich alkaloid diversity of the Amaryllidaceae. As such, Haemantheae should continue to feature prominently in drug discovery efforts targeted at the family.

Conductive polymer mediated earth abundant Z-scheme g-C3N4/Fe2O3 heterostructure with excellent photocatalytic activity

Being the second most abundant metal in the surface of the earth (5.1%), the size confined iron-based photocatalyst is of especially importance for solar energy conversion. Herein, the ternary Z-scheme...

Progress of Wearable and Flexible Electrochemical Biosensors With the Aid of Conductive Nanomaterials

Conductive nanomaterials have recently gained a lot of interest due to their excellent physical, chemical, and electrical properties, as well as their numerous nanoscale morphologies, which enable them to be fabricated into a wide range of modern chemical and biological sensors. This study focuses mainly on current applications based on conductive nanostructured materials. They are the key elements in preparing wearable electrochemical Biosensors, including electrochemical immunosensors and DNA biosensors. Conductive nanomaterials such as carbon (Carbon Nanotubes, Graphene), metals and conductive polymers, which provide a large effective surface area, fast electron transfer rate and high electrical conductivity, are summarized in detail. Conductive polymer nanocomposites in combination with carbon and metal nanoparticles have also been addressed to increase sensor performance. In conclusion, a section on current challenges and opportunities in this growing field is forecasted at the end.

GNP-CeO2- polyaniline hybrid hydrogel for electrochemical detection of peroxynitrite anion and its integration in a microfluidic platform

Peroxynitrite anion (ONOO^-) is an important in vivo oxidative stress biomarker whose aberrant levels have pathophysiological implications. In this study, an electrochemical sensor for ONOO^- detection was developed based on graphene nanoplatelets-cerium oxide nanocomposite (GNP-CeO₂) incorporated polyaniline (PANI) conducting hydrogels. The nanocomposite-hydrogel platform exhibited distinct synergistic advantages in terms of large electroactive surface coverage and providing a conductive pathway for electron transfer. Besides, the 3D porous structure of hydrogel integrated the GNP-CeO₂ nanocomposite to provide hybrid materials for the evolution of catalytic activity towards electrochemical oxidation of ONOO^-. Various microscopic and spectroscopic characterization techniques endorsed the successful formation of GNP-CeO₂-PANI hydrogel. Cyclic voltammetry (CV) measurements of GNP-CeO₂-PANI hydrogel modified screen-printed electrodes (SPE) were carried out to record the current changes influenced by ONOO^-. The prepared sensor demonstrated a significant dose-dependent increase in CV peak current within a linear range of 5-100 µM (at a potential of 1.12 V), and a detection limit of 0.14 with a sensitivity of 29.35 ± 1.4 μA μM^-1. Further, a customized microfluidic flow system was integrated with the GNP-CeO₂-PANI hydrogel modified SPE to enable continuous electrochemical detection of ONOO^- at low sample volumes. The developed microfluidic electrochemical device demonstrated an excellent sensitivity towards ONOO^- under optimal experimental conditions. Overall, the fabricated microfluidic device with hybrid hydrogels as electrochemical interfaces provides a reliable assessment of ONOO^- levels. This work offers considerable potential for understanding the oxidative stress-related disease mechanisms through determination of ONOO^- in biological samples.

Lignosulfonate-Based Conducting Flexible Polymeric Membranes for Liquid Sensing Applications

In this study, lignosulfonate (LS) from the acid sulfite pulping of eucalypt wood was used to synthesize LS-based polyurethanes (PUs) doped with multiwalled carbon nanotubes (MWCNTs) within the range of 0.1-1.4% w/w, yielding a unique conducting copolymer composite, which was employed as a sensitive material for all-solid-state potentiometric chemical sensors. LS-based PUs doped with 1.0% w/w MWCNTs exhibited relevant electrical conductivity suitable for sensor applications. The LS-based potentiometric sensor displayed a near-Nernstian or super-Nernstian response to a wide range of transition metals, including Cu(II), Zn(II), Cd(II), Cr(III), Cr(VI), Hg(II), and Ag(I) at pH 7 and Cr(VI) at pH 2. It also exhibited a redox response to the Fe(II)/(III) redox pair at pH 2. Unlike other lignin-based potentiometric sensors in similar composite materials, this LS-based flexible polymeric membrane did not show irreversible complexation with Hg(II). Only a weak response toward ionic liquids, [C2mim]Cl and ChCl, was registered. Unlike LS-based composites comprising MWCNTs, those doped with graphene oxide (GO), reduced GO (rGO), and graphite (Gr) did not reveal the same electrical conductivity, even with loads up to 10% (w/w), in the polymer composite. This fact is associated, at least partially, with the different filler dispersion abilities within the polymeric matrix.

Advanced Photocatalysts Based on Conducting Polymer/Metal Oxide Composites for Environmental Applications

Photocatalysts provide a sustainable method of treating organic pollutants in wastewater and converting greenhouse gases. Many studies have been published on this topic in recent years, which signifies the great interest and attention that this topic inspires in the community, as well as in scientists. Composite photocatalysts based on conducting polymers and metal oxides have emerged as novel and promising photoactive materials. It has been demonstrated that conducting polymers can substantially improve the photocatalytic efficiency of metal oxides owing to their superior photocatalytic activities, high conductivities, and unique electrochemical and optical properties. Consequently, conducting polymer/metal oxide composites exhibit a high photoresponse and possess a higher surface area allowing for visible light absorption, low recombination of charge carriers, and high photocatalytic performance. Herein, we provide an overview of recent advances in the development of conducting polymer/metal oxide composite photocatalysts for organic pollutant degradation and CO2 conversion through photocatalytic processes.

Recent Trends and Developments in Conducting Polymer Nanocomposites for Multifunctional Applications

Electrically-conducting polymers (CPs) were first developed as a revolutionary class of organic compounds that possess optical and electrical properties comparable to that of metals as well as inorganic semiconductors and display the commendable properties correlated with traditional polymers, like the ease of manufacture along with resilience in processing. Polymer nanocomposites are designed and manufactured to ensure excellent promising properties for anti-static (electrically conducting), anti-corrosion, actuators, sensors, shape memory alloys, biomedical, flexible electronics, solar cells, fuel cells, supercapacitors, LEDs, and adhesive applications with desired-appealing and cost-effective, functional surface coatings. The distinctive properties of nanocomposite materials involve significantly improved mechanical characteristics, barrier-properties, weight-reduction, and increased, long-lasting performance in terms of heat, wear, and scratch-resistant. Constraint in availability of power due to continuous depletion in the reservoirs of fossil fuels has affected the performance and functioning of electronic and energy storage appliances. For such reasons, efforts to modify the performance of such appliances are under way through blending design engineering with organic electronics. Unlike conventional inorganic semiconductors, organic electronic materials are developed from conducting polymers (CPs), dyes and charge transfer complexes. However, the conductive polymers are perhaps more bio-compatible rather than conventional metals or semi-conductive materials. Such characteristics make it more fascinating for bio-engineering investigators to conduct research on polymers possessing antistatic properties for various applications. An extensive overview of different techniques of synthesis and the applications of polymer bio-nanocomposites in various fields of sensors, actuators, shape memory polymers, flexible electronics, optical limiting, electrical properties (batteries, solar cells, fuel cells, supercapacitors, LEDs), corrosion-protection and biomedical application are well-summarized from the findings all across the world in more than 150 references, exclusively from the past four years. This paper also presents recent advancements in composites of rare-earth oxides based on conducting polymer composites. Across a variety of biological and medical applications, the fact that numerous tissues were receptive to electric fields and stimuli made CPs more enticing.

Efficient non-metal based conducting polymers for photocatalytic hydrogen production: comparative study between polyaniline, polypyrrole and PEDOT

Incorporation of conducting polymers (CPs) with TiO2 is considered a promising pathway toward the fabrication of highly efficient non-metal based photocatalysts. Herein, we report the fabrication of TiO2@polyaniline, TiO2@polypyrrole, and TiO2@poly(3,4-ethylenedioxythiophene) photocatalyst heterostructures via the facile wet incipient impregnation method. The mass ratios of CPs in the composites were optimized. The structure, morphology, optical and surface texture of the samples were characterized by XRD, TEM, TGA, DRS, and N2-physisorption techniques. The TiO2@2PEDOT, TiO2@2PPy, and TiO2@5PAn composites were found to exhibit the highest H2 evolution rate (HER) of 1.37, 2.09, and 3.1 mmol h-1 g-1, respectively. Compared to bare TiO2, the HER was significantly enhanced by 16, 24, and 36-fold, respectively. Photoelectrochemical measurements (CV, CA and EIS) were conducted, to evaluate the photoelectric properties of the synthesized composites and assist in understanding the photocatalytic mechanism. The deposition method plays a key-role in forming the photocatalyst/CP interface. This simple impregnation route was found to provide an excellent interface for charge transfer between composite components compared to chemisorption and in situ polymerization methods. This study sheds light on the promising effect of CP incorporation with semiconductor photocatalysts, as a cheap and efficient matrix, on photocatalytic performance.

Imaging the Electrochemical Impedance of Single Cells via Conductive Polymer Thin Film

Many fundamentally important biological phenomena involve the cells to establish and break down the adhesive interactions with the substrate. Here, we report a novel optical method that could directly image the electrochemical impedance of cell-substrate interactions at the single cell level with conventional microscopes and cameras. A thin conductive polymer layer on top of the ITO substrate (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate), PEDOT:PSS) is used as the impedance imaging and sensing layer. A sinusoidal electrochemical potential is applied to the conductive polymer film, and the ion intercalation and transportation in the PEDOT:PSS layer will change the absorption spectrum of the polymer film. The attachment of the cells to the substrate will block and affect the ion doping and dedoping process, and therefore change the color of the polymer film. This process can be captured by any upright or inverted microscope with a simple camera. Utilizing this method, we have successfully imaged the impedance of single-cell attachment, observed the variations of cell-substrate interactions, and measured the impedance changes at different stages of the attachment process. This paper has proposed and successfully demonstrated a new strategy that translates the electrochemical impedance information to an optical signal that could be imaged and used to quantify the local responses. In addition, this method does not need any specially designed optical setup, which may lead to its broad applications in the clinics and biological research laboratories.

The removal of metformin and other selected PPCPs from water by poly(3,4-ethylenedioxythiophene) photocatalyst

The objective of this study was to investigate the photocatalytic removal of PPCPs using poly(3,4-ethylenedioxythiophene) (PEDOT) polymer. PEDOT is a conducting polymer that exhibits excellent photocatalytic activity and was used in this study without any additives or metal co-catalysts. The PEDOT was synthesized using chemical oxidative polymerization and characterized further for composition and morphology. PEDOT, in the presence of UV irradiation, showed >99% degradation of one of the most widely prescribed antidiabetic drugs, metformin, within 60 min. The effect of varying concentration of PEDOT, pH, and light irradiance was studied to achieve maximum photocatalytic efficiency. Two major degradation products of metformin of m/z 116 and 126 were detected using triple quadrupole LC-MS/MS, while the degradation kinetics was found to be of pseudo-first-order. Results revealed that photogenerated electrons, holes, and radical species played a role in the PPCPs' degradation. When a mixture of seven PPCPs in the ultra-pure water matrix was tested, more than 99% removal was observed for most of the PPCPs within 60 min. The removal efficiency decreased in a real wastewater effluent due to the presence of dissolved organic matter; however, still, more than 50% removal was observed for majority of the studied PPCPs. The results of PEDOT reusability revealed that the reuse contributed to the drop in the conductivity and subsequent drop in the photocatalytic activity; however, a simple acid treatment was found to be effective to recoup its conductivity. PEDOT was successfully immobilized on an electrospun fiber mat to enhance its applicability.

Cobalt ion redox and conductive polymers boosted the photocatalytic activity of the graphite carbon nitride–Co3O4 Z-scheme heterostructure

The enhanced photocatalytic hydrogen evolution performance of g-C₃N₄–Co₃O₄ 2D–1D Z-scheme heterojunctions was achieved through the synergistic effect of the cobalt ion redox, conductive polyaniline, and a Co₃O₄ nanobelt.

Polypyrrole Hollow Microspheres with Boosted Hydrophilic Properties for Enhanced Hydrogen Evolution Water Dissociation Kinetics

The water dissociation step (H₂O + M + e^- → M - H_ads + OH^-) is a crucial one toward achieving high-performance hydrogen evolution reaction (HER). The application of electronic conducting polymers (ECPs), such as polypyrrole (PPy), as the electrocatalyst for HER is rarely reported because of their poor adsorption energy per water molecule, which hinders the Volmer step. Herein, we strongly enrich PPy hollow microspheres (PPy-HMS) with attractive HER activity by enhancing their hydrophilic properties through hybridization with good water affinity SiO₂. The as-prepared PPy-coated SiO₂ (PPy@SiO₂-HMS) achieves a current density of 10 mA cm^-2 at -123 mV, which is lower than that of pristine PPy-HMS (-192 mV). Raman and X-ray photospectroscopy analyses reveal that the enhanced HER catalytic capability can be attributed to the strong electronic couplings between PPy and SiO₂, and this improves the adsorption energy per water molecule and in turn accelerates the water dissociation kinetics on PPy. This work highlights the potential application of low-cost ECPs as promising electrocatalysts for water electrolysis.

Conducting Polymer-Based Nanohybrids for Fuel Cell Application

Carbon materials such as carbon graphitic structures, carbon nanotubes, and graphene nanosheets are extensively used as supports for electrocatalysts in fuel cells. Alternatively, conducting polymers displayed ultrahigh electrical conductivity and high chemical stability havegenerated an intense research interest as catalysts support for polymer electrolyte membrane fuel cells (PEMFCs) as well as microbial fuel cells (MFCs). Moreover, metal or metal oxides catalysts can be immobilized on the pure polymer or the functionalized polymer surface to generate conducting polymer-based nanohybrids (CPNHs) with improved catalytic performance and stability. Metal oxides generally have large surface area and/or porous structures and showed unique synergistic effects with CPs. Therefore, a stable, environmentally friendly bio/electro-catalyst can be obtained with CPNHs along with better catalytic activity and enhanced electron-transfer rate. The mass activity of Pd/polypyrrole (PPy) CPNHs as an anode material for ethanol oxidation is 7.5 and 78 times higher than that of commercial Pd/C and bulk Pd/PPy. The Pd rich multimetallic alloys incorporated on PPy nanofibers exhibited an excellent electrocatalytic activity which is approximately 5.5 times higher than monometallic counter parts. Similarly, binary and ternary Pt-rich electrocatalysts demonstrated superior catalytic activity for the methanol oxidation, and the catalytic activity of Pt24Pd26Au50/PPy significantly improved up to 12.5 A per mg Pt, which is approximately15 times higher than commercial Pt/C (0.85 A per mg Pt). The recent progress on CPNH materials as anode/cathode and membranes for fuel cell has been systematically reviewed, with detailed understandings into the characteristics, modifications, and performances of the electrode materials.

Three-dimensionally hierarchical NiCoP@PANI architecture for high-performance hydrogen evolution reaction

Ternary phosphides are attracting great attention in the field of electrocatalytic hydrogen evolution and they have been verified to be highly active for water splitting. Herein, we developed polyaniline (PANI) coated nickel-cobalt metal phosphides nanowire arrays grown on nickel foam (NiCoP@PANI) as hydrogen evolution reaction electrocatalysts. The appearance of PANI with excellent electric conductivity can accelerate H⁺ in electrolyte transfer into H₂ and offer a masking layer to restrain the damage of electrode structural. Besides, the 3D porous structural of nickel foam can act as a skeleton to avoid electrode structure collapse and a channel for electron transfer. The optimized NiCoP@PANI can drive a current density of 10 mA cm^-2 at low overpotential of 80.6 mV in 1 M KOH solution, and satisfactory electrochemical stability with unbroken structure and unchanged composition after electrochemical test.

Electroconductive and free-shapeable nanocomposite hydrogels with an ultrafast self-healing property and high stretchability performance

Conductive self-healing hydrogels as a fascinating class of materials have received much attention in recent years and been widely used in many fields. However, a long healing time and poor electrical conductivity have limited their extended applications. To overcome these shortcomings, we fabricated an excellent conductive self-healing hydrogel by embedding a nanocomposite of Ag nanoparticles and reduced graphene oxide (Ag/RGO) in PVA-borax dynamic networks, which exhibits a relatively high conductivity (4.43 S m-1), good flexibility and excellent self-healing properties without any external stimuli. The multifunctional hydrogel could self-heal within 3 s at room temperature. It also exhibits an excellent free-shapeable property like clay such that it can be modeled into any different complex geometrical shape as desired. It is expected to have potential applications in many fields such as flexible electronic wearable devices, sensors, rechargeable batteries, and biomaterials.

Organic Bioelectronics: From Functional Materials to Next-Generation Devices and Power Sources

Conjugated polymers (CPs) possess a unique set of features setting them apart from other materials. These properties make them ideal when interfacing the biological world electronically. Their mixed electronic and ionic conductivity can be used to detect weak biological signals, deliver charged bioactive molecules, and mechanically or electrically stimulate tissues. CPs can be functionalized with various (bio)chemical moieties and blend with other functional materials, with the aim of modulating biological responses or endow specificity toward analytes of interest. They can absorb photons and generate electronic charges that are then used to stimulate cells or produce fuels. These polymers also have catalytic properties allowing them to harvest ambient energy and, along with their high capacitances, are promising materials for next-generation power sources integrated with bioelectronic devices. In this perspective, an overview of the key properties of CPs and examination of operational mechanism of electronic devices that leverage these properties for specific applications in bioelectronics is provided. In addition to discussing the chemical structure-functionality relationships of CPs applied at the biological interface, the development of new chemistries and form factors that would bring forth next-generation sensors, actuators, and their power sources, and, hence, advances in the field of organic bioelectronics is described.

Polaron and bipolaron induced charge carrier transportation for enhanced photocatalytic H2 production

Photocatalysis is one of the facile approaches for efficient solar energy conversion and storage. However, rapid charge carrier recombination considerably decreases solar to energy conversion efficiency. Herein, polaron and bipolaron rich polypyrrole (PPy) has been utilized as a solid support for effective photogenerated charge carrier separation. Simple oxidative polymerization using a high concentration of ammonium persulfate (APS) induces radical cation/bipolaron formation in PPy due to the cleavage of π-bonds as confirmed by electron paramagnetic resonance spectroscopy (EPR). The formation of radical cations led to an increase of the dielectric constant which retards the charge carrier recombination and thereby enhances the conductivity. Moreover, the polarons and bipolarons induced charge carrier separation in photocatalytic H₂ production was studied with the well-known g-C₃N₄ photocatalyst. It is worth mentioning that compared to bare g-C₃N₄, the PPy supported system showed a drastically enhanced photocatalytic H₂ production rate. A maximum H₂ production rate of 1851 μmoles per g is achieved, which is ∼51 times higher than that of the bare g-C₃N₄ catalyst due to efficient charge carrier separation assisted by radical cations/bipolarons. Thus, utilizing this simple polaron and bipolaron rich PPy solid support could be an effective strategy and alternative for using noble metal cocatalysts to enhance charge carrier separation.

3D Rosa centifolia-like CeO2 encapsulated with N-doped carbon as an enhanced electrocatalyst for Zn-air batteries

Reasonable design and synthesis of high-efficiency rare earth oxides-based materials as alternatives to noble-metal catalysts are of great significance for oxygen electrocatalysis. Herein, we report three-dimension (3D) Rosa centifolia-like CeO₂ encapsulated with N-doped carbon (NC) composites (CeO₂@NC) for enhancing oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities. This synthetic method allows CeO₂ to tune the oxygen vacancy concentration and electronic structure of a series of CeO₂@NC catalysts due to its large oxygen-storage-capacity (OSC) property. Moreover, benefiting from the exposed active sites in NC as well as the synergy between CeO₂ and NC, among as-prepared samples, the resultant CeO₂@NC-900 delivers a half-wave potential (E_1/2) of 0.854 V, which is more positive compared with counterpart of NC-900 (0.806 V) and even comparable to that of commercial Pt/C catalyst (0.855 V). This indicates that the ORR electrocatalytic activity of CeO₂@NC-900 is significantly improved. Meanwhile, CeO₂@NC-900 exhibits satisfactory performance toward OER. For practical application, the CeO₂@NC-900 involved rechargeable Zn-air battery possesses excellent energy efficiency, superior stability, and large energy density (666.1 Wh kg_Zn^-1 at 5 mA cm^-2). This approach provides a valid way to develop advanced rare earth oxides-based materials for energy applications.

Zn- and Cd-based coordination polymers with a novel anthracene dicarboxylate ligand for highly selective detection of hydrogen peroxide

A one-dimensional {[Zn(L)(DMF)2]}n (1) and a three-dimensional {[Cd(L)(DMF)]·DMF}n (2) coordination polymer based on the novel anthracene derivative H2L (H2L = 4,4'-(9,10-anthracenediyl)dicinnamic acid) were obtained by solvothermal synthesis and charaterised by single-crystal and powder X-ray diffraction, thermogravimetry, and infrared spectroscopy. The anthracene derivative H2L and coordination polymers 1 and 2 were used to modify a glassy carbon electrode and as such served as an active material for detection of H2O2. Cyclic voltammograms in the potential range from 0 to -0.5 V revealed concentration-dependent cathodic current in all three cases with a lower detection limit of 200 μM. The electrode modified with compound 2 showed the best performance towards hydrogen peroxide detection. The results suggest that the development of electrodes modified with inorganic polymers based on highly conjugated ligands can serve as potential electrocatalytic materials.

Highly efficient electrocatalytic hydrogen evolution reaction on carbonized porous conducting polymers

A rational design of an efficient and inexpensive electrocatalyst for water splitting still remains a challenge. Porous conducting polymers are attractive materials which not only provide a high surface area for electrocatalysis but also absorb light which can be harnessed in photoelectrocatalysis. Here, a novel and inexpensive electrochemical approach is developed to obtain nanoporous conducting copolymers with tunable light absorbance and porosity. By fine-tuning the copolymer composition and upon heat treatment, an excellent electrocatalytic hydrogen evolution reaction (HER) was achieved in alkaline solution with an overpotential of just 77 mV to obtain a current density of 10 mA cm−2. Such an overpotential is remarkably low compared with other reported values for polymers in an alkaline medium. The nanoporous copolymer developed here shows a great promise of using metal-free electrocatalysts and brings about new avenues for exploitation of these porous conducting polymers.

Polymer Nanofibers Exhibiting Remarkable Activity in Driving the Living Polymerization under Visible Light and Reusability

Visible light-driving syntheses have emerged as a powerful tool for organic synthesis and for the preparation of macromolecules under mild and environmentally benign conditions. However, precious but nonreusable photosensitizers or photocatalysts are often required to activate the reaction, limiting its practicality. Here, it is reported that poly(1,4-diphenylbutadiyne) (PDPB) nanofibers exhibit remarkable activity in driving the living free radical polymerization under visible light. Moreover, PDPB nanofibers are very stable under irradiation of visible light and can be reused without appreciable loss of activity even after repeated cycling. The nanofiber will be a promising photocatalyst with excellent reusability and stability for the reactions driven by visible light.