Hierarchical structures on platinum-iridium substrates enhancing conducting polymer adhesion

Conducting polymers(CPs),including poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS),are promising coating materials for neural electrodes.However,the weak adhesion of CP coatings to substrates such as platinum-iridium is a significant challenge that limits their practical application.To address this issue,we used femtosecond laser-prepared hierarchical structures on platinum-iridium(Pt-Ir)substrates to enhance the adhesion of PEDOT:PSS coatings.Next,we used cyclic voltammetry(CV)stress and accelerated aging tests to evaluate the stability of both drop cast and electrodeposited PEDOT:PSS coatings on Pt-Ir substrates,both with and without hierarchical structures.Our results showed that after 2000 CV cycles or five weeks of aging at 60℃,the morphology and electrochemical properties of the coatings on the Pt-Ir substrates with hierarchical structures remained relatively stable.In contrast,we found that smooth Pt-Ir substrate surfaces caused delamination of the PEDOT:PSS coating and exhibited both decreased charge storage capacity and increased impedance.Overall,enhancing the stability of PEDOT:PSS coatings used on common platinum-iridium neural electrodes offers great potential for improving their electrochemical performance and developing new functionalities.

Conducting Polymer-Based e-Refinery for Sustainable Hydrogen Peroxide Production

Electrocatalysis enables the industrial transition to sustainable production of chemicals using abundant precursors and electricity from renewable sources.De-centralized production of hydrogen peroxide(H_(2)O_(2))from water and oxygen of air is highly desirable for daily life and industry.We report an effective electrochemical refinery(e-refinery)for H_(2)O_(2)by means of electrocatalysis-controlled comproportionation reaction(2_(H)O+o→2HO),feeding pure water and oxygen only.Mesoporous nickel(Ⅱ)oxide(NiO)was used as electrocatalyst for oxygen evolution reaction(OER),producing oxygen at the anode.Conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)drove the oxygen reduction reaction(ORR),forming H_(2)O_(2)on the cathode.The reactions were evaluated in both half-cell and device configurations.The performance of the H_(2)O_(2)e-refinery,assembled on anion-exchange solid electrolyte and fed with pure water,was limited by the unbalanced ionic transport.Optimization of the operation conditions allowed a conversion efficiency of 80%.

A review on electronically conducting polymers for lithium-sulfur battery and lithium-selenium battery:Progress and prospects

Lithium-sulfur(Li-S) batteries and lithium-selenium(Li-Se) batteries,as environmental protection energy storage systems with outstanding theoretical specific capacities and high energy densities,have become the hotspots of current researches.Besides,elemental S(Se) raw materials are widely sourced and their production costs are both low,which make them considered one of the new generations of high energy density electrochemical energy storage systems with the most potential for development.However,poor conductivity of elemental S/Se and the notorious "shuttle effect" of lithium polysulfides(polyselenides) severely hinder the commercialization of Li-S/Se batteries.Thanks to the excellent electrical conductivity and strong absorption of lithium polysulfide(polyselenide) about electronically conducting polymer,some of the above thorny problems have been effectively alleviated.The review presents the fundamental studies and current development trends of common electronically conducting polymers in various components of Li-S/Se batteries,which involves polyaniline(PANI) polypyrrole(PPy),and polythiophene(PTh) with its derivatives,e.g.polyethoxythiophene(PEDOT) and poly(3,4-ethylene dioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS).Finally,the review not only summarizes the research directions and challenges facing the application of electronically conducting polymers,but also looks forward to the development prospects of them,which will provide a way for the practical use of electronically conducting polymers in Li-S/Se batteries with outstanding electrochemical properties in the short run.

Conducting Polymers Meet Lithium-Sulfur Batteries:Progress,Challenges,and Perspectives

Lithium-sulfur(Li-S)batteries have attracted increased interest because of the high theoretical energy density,low cost,and environmental friendliness.Conducting polymers(CPs),as one of the most promising materials used in Li-S batteries,can not only facilitate electron transfer and buffer the large volumetric change of sulfur benefiting from their porous structure and excellent flexibility,but also enable stronger physical/chemical adsorption capacity toward polysulfides(LiPSs)when doped with abundant heteroatoms to promote the sulfur redox kinetics and achieve the high sulfur loading.This review firstly introduces the properties of various CPs including structural CPs(polypyrrole(PPy),polyaniline(PANi),polyethylene dioxothiophene[PEDOT])and compound CPs(polyethylene oxide(PEO),polyvinyl alcohol(PVA)and poly(acrylic acid)[PAA]),and their application potential in Li-S batteries.Furthermore,the research progress of various CPs in different components(cathode,separator,and interlayer)of Li-S batteries is systematically summarized.Finally,the application perspective of the CPs in Li-S batteries as a potential guidance is comprehensively discussed.

Electrochemical Impedance Analysis of Biofunctionalized Conducting Polymer-Modified Graphene-CNTs Nanocomposite for Protein Detection

We report an electrodeposited poly(pyrrole-co-pyrrolepropylic acid) copolymer modified electroactive graphene-carbon nanotubes composite deposited on a glassy carbon electrode to detect the protein antigen(cTnI). The copolymer provides pendant carboxyl groups for the site-specific covalent immobilization of protein antibody, antitroponin I. The hybrid nanocomposite was used as a transducer for biointerfacial impedance sensing for cTnI detection.The results show that the hybrid exhibits a pseudo capacitive behaviour with a maximum phase angle of 49° near 1 Hz,which is due to the inhomogeneous and porous structure of the hybrid composition. The constant phase element of copolymer is 0.61(n = 0.61), whereas, it is 0.88(n = 0.88) for the hybrid composites, indicating a comparatively homogeneous microstructure after biomolecular functionalization. The transducer shows a linear change in charge transfer characteristic(R_(et)) on cTnI immunoreaction for spiked human serum in the concentration range of 1.0 pg mL^(-1)–10.0 ng mL^(-1). The sensitivity of the transducer is 167.8 ± 14.2 Ω cm^2 per decade, and it also exhibits high specificity and good reproducibility.

Vapor Phase Polymerization Deposition Conducting Polymer Nanocomposites on Porous Dielectric Surface as High Performance Electrode Materials

We report chemical vapor phase polymerization(VPP) deposition of poly(3,4-ethylenedioxythiophene)(PEDOT) and PEDOT/graphene on porous dielectric tantalum pentoxide(Ta_2O_5) surface as cathode films for solid tantalum electrolyte capacitors. The modified oxidant/oxidant-graphene films were first deposited on Ta_2O_5 by dip-coating, and VPP process was subsequently utilized to transfer oxidant/oxidant-graphene into PEDOT/PEDOT-graphene films. The SEM images showed PEDOT/PEDOT-graphene films was successfully constructed on porous Ta_2O_5 surface through VPP deposition, and a solid tantalum electrolyte capacitor with conducting polymer-graphene nano-composites as cathode films was constructed. The high conductivity nature of PEDOT-graphene leads to resistance decrease of cathode films and lower contact resistance between PEDOT/graphene and carbon paste. This nano-composite cathode films based capacitor showed ultralow equivalent series resistance(ESR) ca. 12 m? and exhibited excellent capacitance-frequency performance, which can keep 82% of initial capacitance at 500 KHz. The investigation on leakage current revealed that the device encapsulation process has no influence on capacitor leakage current, indicating the excellent mechanical strength of PEDOT/PEDOT-gaphene films. This high conductivity and mechanical strength of graphene-based polymer films shows promising future for electrode materials such as capacitors, organic solar cells and electrochemical energy storage devices.

Current-voltage characteristics of individual conducting polymer nanotubes and nanowires

We report the current-voltage （I-V） characteristics of individual polypyrrole nanotubes and poly（3,4- ethylenedioxythiophene） （PEDOT） nanowires in a temperature range from 300 K to 2 K. Considering the complex structures of such quasi-one-dimensional systems with an array of ordered conductive regions separated by disordered barriers, we use the extended fluctuation-induced tunneling （FIT） and thermal excitation model （Kaiser expression） to fit the temperature and electric-field dependent I-V curves. It is found that the I-V data measured at higher temperatures or higher voltages can be well fitted by the Kaiser expression. However, the low-temperature data around the zero bias clearly deviate from those obtained from this model. The deviation （or zero-bias conductance suppression） could be possibly ascribed to the occurrence of the Coulomb-gap in the density of states near the Femi level and/or the enhancement of electron-electron interaction resulting from nanosize effects, which have been revealed in the previous studies on low-temperature electronic transport in conducting polymer films, pellets and nanostructures. In addition, similar I--V characteristics and deviation are also observed in an isolated K0.27MnO2 nanowire.

STUDIES ON ENHANCED CONDUCTIVITY OF STRETCHED CONDUCTING POLYMERS

A physical model of series of the conductivity on chain and the interchain conductivitybetween chains is proposed to explain enhanced conductivity of stretched conducting polymers.This model suggests that the enhanced conductivity for stretched conducting polymers might bedue to increasing of the interchain conductivity between chains along the elongation direction afterdrawing processes if the conductivity on chain is assumed much larger than that of the interchainconductivity between chains. According to this model, it is expected that the temperaturedependence of conductivity measured by four-probe method for stretched conducting polymers iscontrolled by a variation of the interchain conductivity between chains with temperature, whichcan be used to explain that a metallic temperature dependence of conductivity for stretchedconducting polymers is not observed although the conductivity along the elongation direction isenhanced by two or three orders of magnitude.

INFRARED EMISSIVITY OF CONDUCTING POLYMERS

The infrared emissivity of conducting polymers in 8—20μm and at 50—150℃ in the direction of normal line has been measured as a function of wavelength, conductivity at room temperature, counterion, doping levels, measuring temperature and thickness of sample.

Field Emission Characteristics of Conducting Polymer Films Conditioned by Electric Discharge

A pure conducting polymer （PANI-CSA） film conditioned by an electric discharge was tentatively utilized as an cathode for emitting electrons under electric fields. The emission of electrons was observed using a phosphor （ZnO：Zn） screen excited by electrons from the conditioned film. The film morphology was investigated using a scanning electron microscope and it was found that undulate whisker-like sites formed on the surface. The emission was presumably due to the undulate whisker-like sites. The field enhancement factor was estimated to be as high as 1150. The electron emitting process of the PANI-CSA film conditioned by electric discharge was also discussed.

Characteristics and Application of Conducting Polymer Sensor

Conducting polymers sensors have been very interesting that it can detect wide variety of functionalities,however these materials have to solve humidity contaminant,poor reversibility and selectivity.To improve this problems,we investigated pretreatment such as soaking in methanol and thermal treatment in N_2.This process improved stability, reversibility and response time and recovery time.To overcome humidity contaminant coated hydrophobic polymer was reduced above 50% at RH10%.For sensor array structure was fabricated for enhancing selectivity of gas vapor.Conducting polymer sensor array had several application in environmental and medical science the method of principal component analysis.

Electrochemical Formation of Polypyrrole-carboxymethylcellulose Conducting Polymer Composite Films

The electrochemical preparation of polypyrrole-carboxymethylcellulose （PPY-CMC） conducting polymer composite films on indium tin oxide （ITO） glass electrode from an aqueous solution containing pyrrole monomer, ptoluenesulfonate electrolyte and carboxymethylcellulose insulating polymer is reported. The characterization by Fourier transform infrared spectroscopy （FT-IR） shows that carboxymethylcellulose （CMC） has been successfully incorporated into polypyrrole structure forming PPY-CMC polymer composite films. The conductivity of the prepared composite films was found to increase with increaseing CMC concentration in pyrrole solution, The optical microscopic results show the influence of CMC concentration in the pyrrole solution over the morphological changes of the prepared films. The dynamic mechanical analysis （DMA） on the prepared PPY-CMC film reveals the higher plastic property of the PPY-CMC composite film.

Rectifying effect of heterojunctions between metals and doped conducting polymer nanostructure pellets

This paper reports that the Schottky junctions between low work function metals （e.g. Al and In） and doped semiconducting polymer pellets （e.g. polyaniline （PANI） microsphere pellet and polypyrrole （PPy） nanotube pellet） have been prepared and studied. Since Ag is a high work function metal which can make an ohmic contact with polymer, silver paste was used to fabricate the electrodes. The Al/PANI/Ag heterojunction shows an obvious rectifying effect as shown in I - V characteristic curves （rectifying ratio γ = 5 at ±6 V bias at room temperature）. As compared to the Al/PANI/Ag, the heterojunction between In and PANI （In/PANI/Ag） exhibits a lower rectifying ratio γ= 1.6 at ±2 V bias at room temperature. In addition, rectifying effect was also observed in the heterojunctions Al/PPy/Ag （γ = 3.2 at ±1.6 V bias） and In/PPy/Ag （γ = 1.2 at ±3.0 V bias）. The results were discussed in terms of thermoionic emission theory.

MEASUREMENT METHOD AND PHYSICAL MODEL OF VSC CONDUCTIVITY AND ITS APPLICATIONS IN CONDUCTING POLYMERS

Method of VSC (Voltage Shorted Compaction)can be used to determine the intrinsic temperature dependence ofconductivity ofpolycrystalline compaction. The experimental conditions and technical key for preparation of VSC device and its physical model as well as its applications in conducting polymers are discussed in detail.

Towards Ultrahigh Capacity and High Cycling Stability Lithium-Conducting Polymer Batteries by In Situ Construction of Nanostructured Porous Cathodes

Conducting polymers(CPs)have long been studied as cathode materials for lithium-ion batteries,but the low doping level(maximum:30–50%or even lower)and poor cycling stability limit their applications.Herein,we have developed a method of nanoporeconfined in situ electropolymerization to prepare nanostructured polythiophene-type porous cathodes,achieving significantly improved doping availability and long cycle life.It was verified that the nanosized polymer formed in situ and loose porous structure are conducive to the doping reaction and maintain high electrochemical stability.The constructed thieno[3,2-b]thiophene(TtTP)/active carbon cathode delivers an ultrahigh reversible capacity of 309.2 mAh g^(−1)(doping level up to 80.9%)along with an ultrahigh energy density of 1252.3 Wh Kg^(−1),and an ultrahigh rate capability(172.4 mAh g^(−1) at 30 A g^(−1)),which far exceed all the CPs and even all the p-type organic cathode materials reported.Moreover,an excellent long cycle life of 2000 cycles at 5 A g^(−1) is also revealed,which is a new record for CPs-based cathode materials in nonaqueous lithium-ion batteries.Our method provides an effective strategy to improve the doping level and cycling stability of CP-based cathode materials.

Nanoscale engineering of conducting polymers for emerging applications in soft electronics

Soft electronics featuring exceptional mechanical compliance and excellent electrical performance hold great promise for applications in soft robotics,artificial intelligence,bio-integrated electronics,and wearable electronics.Intrinsically stretchable and conductive materials are crucial for soft electronics,enabling large-area and scalable fabrication,high device density,and good mechanical compliance.Conducting polymers are inherently stretchable and conductive.They can be precisely synthesized from vastly available building blocks,and thus they provide a fruitful platform for fabricating soft electronics.However,amorphous bulk-phase conducting polymers typically exhibit poor mechanical and electrical characteristics.Consequently,it is highly desirable to develop novel engineering approaches to overcome the intrinsic limitations of conducting polymers.In recent years,numerous engineering strategies have been developed to enhance their performances in soft electronic devices via constructing various nanostructures.In this review,we first summarize several unique methodologies to fabricate conducting polymer-based nanostructures.We then discuss how nanoscale engineering approaches can improve several crucial parameters,including electrical conductivity,stretchability,sensitivity,and self-healing property of conducting polymers.Moreover,we also discuss device-level integration of conducting polymer-based nanostructures with other materials for applications in skin-inspired electronics and bio-integrated electronics.Finally,we provide perspectives on challenges and future directions in engineering nanostructured conducting polymers for soft electronics.

Semiconducting covalent organic frameworks:a type of two-dimensional conducting polymers

In recent years,as a new class of two-dimensional polymer,covalent organic frameworks（COFs） have attracted intensive attention and developed rapidly.This review provides an overview of a type of COFs which can be utilized as organic semiconductors.Carefully choosing monomers as the building blocks will bestow different types of semiconducting character on COFs.We summarize the p-type,n-type and ambipolar semiconducting COFs and highlight the effects of π-functional building blocks on the photoconductive behaviors of the semiconducting COFs.

Recent progress on nanostructured conducting polymers and composites:synthesis,application and future aspects

Conducting polymers （CPs） have been widely investigated due to their extraordinary advantages over the traditional materials, including wide and tunable electrical conductivity, facile production approach, high mechanical stability, light weight, low cost and ease in material processing. Compared with bulk CPs, nanostructured CPs possess higher electrical conductivity, larger surface area, superior electro- chemical activity, which make them suitable for various ap- plications. Hybridization of CPs with other nanomaterials has obtained promising functional nanocomposites and achieved improved performance in different areas, such as energy sto- rage, sensors, energy harvesting and protection applications. In this review, recent progress on nanostructured CPs and their composites is summarized from research all over the world in more than 400 references, especially from the last three years. The relevant synthesizing experiences are outlined and abundant application examples are illustrated. The ap- proaches of production of nanostructured CPs are discussed and the efficacy and benefits of newest trends for the pre- paration of multifunctional nanomaterials/nanocomposites are presented. Mechanism of their electrical conductivity and the ways to tailor their properties are investigated. The re- maining challenges in developing better CPs based nanoma- terials are also elaborated.

Design and construction of three-dimensional graphene/conducting polymer for supercapacitors

Three-dimensional graphene/conducting polymer（3DGCP） composites have received significant attention in recent years due to their unique structures and promising applications in energy storage.With the structural diversity of graphene and π-functional conducting polymers via rich chemical routes,a number of 3DGCP composites with novel structures and attractive performance have been developed.Particularly,the hierarchical porosity,the interactions between graphene and conducting polymers as well as the their synergetic effects within 3DGCP composites can be well combined and elaborated by various synthetic methods,which made 3DGCP composites show unique electrochemical properties and significantly improved performance in energy storage fields compared to other graphenebased composites.In this short review,we present recent advances in 3DGCP composites in developing effective strategies to prepare 3DGCP composites and exploring them as a unique platform for supercapacitors with unprecedented performance.The challenges and future opportunities are also discussed for promotion of further study.