Electroactive Properties Research Articles

Electrochemical Determination of Sunset Yellow Using an Electrochemically Prepared Graphene Oxide Modified – Pencil Graphite Electrode (EGO-PGE)

Sunset Yellow (E110) is an azo food artificial dye and has a wide range of applications. When ingested in excess, it can lead to many serious health problems, so it is significant to rapidly determine Sunset Yellow. In this study, a modified electrode was developed by making use of electroactive properties of Sunset Yellow. Using a chronoamperometry method, an electrochemically prepared graphene oxide modified pencil graphite electrode was prepared in one-step by applying a + 1.9 V constant potential for 60 seconds in 5.0 M sulfuric acid. Cyclic voltammetry, electrochemical impedance spectroscopy, X-ray powder diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy were used to characterize the electrochemical properties and surface morphology of the modified electrode. Electrochemical measurements were carried out using differential pulse voltammetry. The influence of pH on the electrochemical determination of Sunset Yellow was investigated. The effects of possible substances that may interfere and the repeatability and reproducibility of the developed sensor platform were examined. Under the optimized conditions, the limits of detection and quantitation were 0.057 µM and 0.19 µM, respectively. The applicability of the developed protocol to real samples was investigated and good recovery values were achieved. The developed sensor platform stands out with features such as short preparation and analysis time, simplicity, low cost, sensitivity and selectivity.

Influence of the Stabilization Process on the Piezotronic Performance of Electrospun Silk Fibroin

AbstractThe ability to provide the energy needed while keeping the product ergonomic, lightweight and non‐intrusive, is the ultimate challenge for wearable technologies. In this work, silk fibroin (SF) is electrospun and immersed in liquid methanol (MeOH) over 3 and 48 h. A phase transformation from water‐soluble α‐helix (silk I) to insoluble β‐sheets (silk II) is observed, increasing the protein crystallinity and the membrane stability against aqueous environments. The phase transformation from silk I to silk II leads to a reorganization of the polymer chains inside the protein fibers, which influences the dipolar reorientation of the SF molecules. A cost‐effective energy harvester device is built, showing an open‐circuit output voltage of 4.5 V, a power density around 1 µmW cm−2, with an efficiency up to 6%, and a mechano‐sensitivity of 0.078 ± 0.01 V kPa−1. This work provides new insights into the effect of the stabilization process of the SF membranes and its influence on the electroactive properties of the protein. Overall, the electromechanical and energy harvesting performance of the SF membranes opens new opportunities for applications as wearable self‐powered microelectronics, with the potential to be fully integrated inside clothing, with potential applications in personalized healthcare devices and sports training systems.

Polystyrene-polyaniline core-shell composite particles using a bifunctional selectively polymerizable monomer as the interfacial linkage

Polystyrene-polyaniline core-shell composites were synthesized using a bifunctional monomer (benzenaminium 4-styrenesulfonate) as the interface. For the core synthesis, the monomer allowed the stabilization of styrene emulsion polymerizations, performing the function of a conventional reactive surfactant, copolymerizing with styrene by free radical polymerization. Then, the monomer allowed the synthesis of polyaniline in the emeraldine salt form by oxidative polymerization to obtain the shell. It was found that the particle size was inversely dependent on the monomer content, as established by the classical theory of emulsion polymerization. The product obtained is a complex system in which the core is a copolymer of styrene and styrenesulfonate and the shell is polyaniline with two doping agents. The polyaniline shell presented optical and electroactive properties, characterized by UV–vis spectroscopy and cyclic voltammetry. Finally, the core-shell was evaluated for H2S detection showing promising results for the design of electrochemical sensors.

Conducting Polymers for Tissue Regeneration in Vivo

Conducting polymers (CPs) have unique electroactive properties that have inspired significant investigation into their use as biomaterials (CP-BMs) for regenerative engineering. Their physical and ...

Energy Harvesting Applications from Poly(ε-caprolactone) Electrospun Membranes

Piezoelectricity is associated with crystalline materials that have noncentrosymmetric crystal units. This work reports the electroactive properties of poly(e-caprolactone) (PCL) membranes produced...

Polyaniline supercapacitor electrode and carbon fiber graphene oxide: Electroactive properties at the charging limit

Electroactive materials have presented increasingly relevant application potentials as energy storage, because of the use of 5G technologies, artificial intelligence, IoT and batteries for electric vehicles. The objective of this work was to evaluate their electroactive properties in different potential applications and to test the electrode charge limit for energy storage devices. Structural carbon fiber composite materials coated by electrochemical synthesis of polyaniline with graphene oxide were obtained. The electrodes were characterized by GCD (with and without cutoff), FEG, FTIR, Raman, CV, EIS and 4 probes. The electrodes can be classified with supercapacitive properties according to the Ragone Diagram and applied to different potential variations reaching a charging limit (potential limit that stores the largest amount of charge). Mapping of specific power and energy during cycling reveals that the GO electrode confers structural stability to the PANI and maintains the material’s electroactive properties elevated over 500 cycles.

Conducting Polymer Grafting: Recent and Key Developments.

Since the discovery of conductive polyacetylene, conductive electroactive polymers are at the focal point of technology generation and biocommunication materials. The reasons why this research never stops growing, are twofold: first, the demands from the advanced technology towards more sophistication, precision, durability, processability and cost-effectiveness; and second, the shaping of conducting polymer research in accordance with the above demand. One of the major challenges in conducting polymer research is addressing the processability issue without sacrificing the electroactive properties. Therefore, new synthetic designs and use of post-modification techniques become crucial than ever. This quest is not only advancing the field but also giving birth of new hybrid materials integrating merits of multiple functional motifs. The present review article is an attempt to discuss the recent progress in conducting polymer grafting, which is not entirely new, but relatively lesser developed area for this class of polymers to fine-tune their physicochemical properties. Apart from conventional covalent grafting techniques, non-covalent approach, which is relatively new but has worth creation potential, will also be discussed. The aim is to bring together novel molecular designs and strategies to stimulate the existing conducting polymer synthesis methodologies in order to enrich its fascinating chemistry dedicated toward real-life applications.

Electroactive actuator based on polyurethane nanofibers coated with polypyrrole through electrochemical polymerization: a competent method for developing artificial muscles

In the present study, the electrochemical polymerization was carried out to coat the surface of electrospun polyurethane (PU) nanofibers with conductive electroactive polypyrrole (PPy) towards production of Faradaic bending actuators. For this purpose, the surface of electrospun nanofibers was first coated with a thin layer of gold using physical vapor deposition (PVD). PPy was then coated on the surface of prepared nanofibers using different consumed electric charges ranging from 0.5 to 5 C. The produced samples were characterized with respect to surface morphology, electrical properties, electrochemical properties and finally bending actuation performance of the produced actuators. The synthesis of PPy on the surface of nanofibers by the electrochemical polymerization process as well as preservation of the fibrous and porous structure of the samples was confirmed by SEM images. In the polymerization process, the amount of PPy coating on the surface of PU nanofibers increased dramatically with increasing the consumed electric charge. The results of the electrical properties of the produced nanofibrous layers showed that the surface resistivity of the produced PU/PPy nanofibrous layer was decreased from 719.5 to 51.3 Ω/sq for samples produced with the consumed charges of 0.5 and 5.0 C, respectively. Moreover, the electroactive properties of produced actuators were evaluated by cyclic voltammetry technique in a 0.1 M aqueous electrolyte solution of LiClO4 between potentials of −0.6 to 0.8 V. The results revealed that the electroactive properties of produced actuators were improved with increasing the amount of PPy coating. The evaluation of the bending actuation performance of the actuators showed that the angular displacement of the samples produced with consumed charges of 2, 3, 4 and 5 C in a potential cycle was 48°, 153°, 190° and 225°, respectively. These actuators have the potential to be applied in the fields of medicine, robotics and smart textiles.

Cultivating electroactive microbes—from field to bench

Electromicrobiology is an emerging field investigating and exploiting the interaction of microorganisms with insoluble electron donors or acceptors. Some of the most recently categorized electroactive microorganisms became of interest to sustainable bioengineering practices. However, laboratories worldwide typically maintain electroactive microorganisms on soluble substrates, which often leads to a decrease or loss of the ability to effectively exchange electrons with solid electrode surfaces. In order to develop future sustainable technologies, we cannot rely solely on existing lab-isolates. Therefore, we must develop isolation strategies for environmental strains with electroactive properties superior to strains in culture collections. In this article, we provide an overview of the studies that isolated or enriched electroactive microorganisms from the environment using an anode as the sole electron acceptor (electricity-generating microorganisms) or a cathode as the sole electron donor (electricity-consuming microorganisms). Next, we recommend a selective strategy for the isolation of electroactive microorganisms. Furthermore, we provide a practical guide for setting up electrochemical reactors and highlight crucial electrochemical techniques to determine electroactivity and the mode of electron transfer in novel organisms.

Cover Feature: Effect of Electrolyte Ions on the Formation, Electroactivity, and Rectification Properties of Films Obtained by Electrografting (ChemElectroChem 4/2020)

Cover Feature: Effect of Electrolyte Ions on the Formation, Electroactivity, and Rectification Properties of Films Obtained by Electrografting (ChemElectroChem 4/2020)

Transition-Metal-Functionalized DNA Double-Crossover Tiles: Enhanced Stability and Chirality Transfer to Metal Centers.

The double crossover junction (DX) is a fundamental building block for generating complex and varied structures from DNA. However, its implementation in functional devices is limited to the inherent properties of DNA itself. Here, we developed design strategies to generate the first metal-DX DNA tiles (DXM ) by site-specifically functionalizing the tile crossovers with tetrahedral binding pockets that coordinate CuI . These DX junctions bind two CuI ions independently at distinct sites, display greater thermal stability than native DX tiles upon metalation, and melt in a cooperative fashion. In addition, the right-handed helical chirality of DNA is transferred to the metal centers. Our tiles display high metal ion selectivity, such that CuII is spontaneously reduced to CuI in situ. By modifying our design over three generations of tiles, we elucidated the thermodynamic and geometric requirements for the successful assembly of DXM tiles, which have direct applicability in developing robust, stable DNA-based materials with electroactive, photoactive, and catalytic properties.

Transition‐Metal‐Functionalized DNA Double‐Crossover Tiles: Enhanced Stability and Chirality Transfer to Metal Centers

AbstractThe double crossover junction (DX) is a fundamental building block for generating complex and varied structures from DNA. However, its implementation in functional devices is limited to the inherent properties of DNA itself. Here, we developed design strategies to generate the first metal–DX DNA tiles (DXM) by site‐specifically functionalizing the tile crossovers with tetrahedral binding pockets that coordinate CuI. These DX junctions bind two CuI ions independently at distinct sites, display greater thermal stability than native DX tiles upon metalation, and melt in a cooperative fashion. In addition, the right‐handed helical chirality of DNA is transferred to the metal centers. Our tiles display high metal ion selectivity, such that CuII is spontaneously reduced to CuI in situ. By modifying our design over three generations of tiles, we elucidated the thermodynamic and geometric requirements for the successful assembly of DXM tiles, which have direct applicability in developing robust, stable DNA‐based materials with electroactive, photoactive, and catalytic properties.

Physical and electrochemical investigations on hybrid materials synthesized by polyaniline with various amounts of ZnO nanoparticle

Hybrid-materials were prepared via chemical polymerization in presence of aniline with various amounts of ZnO. The structural, functional, optical, morphological and electrical properties of nanocomposites were investigated by XRD, FT-IR, UV–Visible, TGA, SEM and electrical conductivity. XRD and SEM analysis shows the formation of nanocomposite and confirms the amorphous and crystalline nature of material. FT-IR spectrum reveals the functional groups present in the samples and the electroactive and optical properties were affected. Results showed that our nanocomposites exhibited a direct optical energy gap that decreased from 3.12 to 2.76 eV with the increment of the amounts of ZnO in nanocomposite.

Synthesis of reduced graphene oxide modified Cu (rGO-Cu) by gamma irradiation and its electroactive properties

Electroactive materials with excellent performance are developed to be applied in different fields. In this study, Graphene Oxide (GO) was synthesized using the Hummer method then reduced and modified with Cu trough gamma irradiation (radiolytic reduction) for dose variations. The optimum dose that produces the highest electroactive is 35 kGy which was tested with cyclic voltammetry. The results of FTIR analysis show the characteristics of functional groups found in GO and rGO are different. The modification of rGO with Cu was successfully shown from the results of XRD and SEM-EDX analysis. The results of the XRD analysis showed that there are two peaks at position 2 theta 10.58° which showed the presence of GO and at position 2 theta 42.55° which indicates the presence of Cu. The results of the SEM-EDX analysis showed that there is 2.25% wt of Cu on the surface of the rGO.

An electrochemical sandwich-type aptasensor for determination of lipocalin-2 based on graphene oxide/polymer composite and gold nanoparticles

In this work, we reported an electrochemical aptasensor based on the poly-3-amino-1,2,4-triazole-5-thiol/graphene oxide composite (P(ATT)-GO) and gold nanoparticles (AuNPs) modified graphite screen-printed electrode (GSPE) (GSPE/P(ATT)-GO/AuNPs) for determination of lipocalin-2 (LCN2) (neutrophil gelatinase-associated lipocalin). A sandwich based strategy was utilized to enhance the electrochemical signal. First, a thiol tethered DNA aptamer was immobilized onto the composite electrode. Then, the LCN2 solution was incubated with the aptamer modified GSPE/P(ATT)-GO/AuNPs. Secondary aptamer (Apt2) peculiar to the LCN2 and labeled with biotin was interacted with the LCN2. A streptavidin-alkaline phosphatase conjugate was then applied to the surface. The determination of LCN2 was performed by using the electroactive property of α-naphthol which is acquired the product from the interaction between alkaline phosphatase and α-naphthyl phosphate. The constructed electrode was characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The aptamer modified GSPE/P(ATT)-GO/AuNPs showed the superior electrocatalytic performance towards the voltammetric determination of LCN2 with a wide linear range (1.0–1000.0 ng/mL) and a low limit of detection (LOD) (0.3 ng/mL). The proposed aptasensor revealed the excellent sensitivity, anti-interference ability and reproducibility which approved that the GSPE/P (ATT)-GO/AuNPs is a promising composite for the sensitive detection of LCN2. The fabricated aptasensor was applied for the determination of LCN2 in fetal bovine serum samples using the standard addition method and the recovery values were in the range of 99.2% and 103.22%.

Effect of Electrolyte Ions on the Formation, Electroactivity, and Rectification Properties of Films Obtained by Electrografting

AbstractThe oxidation of 4‐(4‐nitrophenyl)butyrate ions in acetonitrile was used to modify glassy carbon surfaces with films bearing 3‐(4‐nitrophenyl)propyl groups. The main features of the voltammetric reduction of the grafted nitrophenyl groups were studied in two different supporting electrolytes; n‐Bu4NPF6 and Me4NPF6. The best response was obtained with the less bulky electrolyte, which was explained by the major capability of these ions to diffuse inside the channels of the grafted film, as well as the better stabilization of the radical anions generated during the reduction process. It was also shown that the films electrografted in presence of the bulky n‐Bu4NPF6 are thicker but less compact than those prepared in Me4NPF6. The amount of nitrophenyl groups in the grafted film that can be reduced depends on the size of the electrolyte ions. The permeation of the electrolyte ions inside the film channels determines also the voltammetric behavior of ferrocene as redox probe. A current rectification phenomenon was observed in acetonitrile solutions of bulky and hydrophobic electrolytes like n‐Bu4NPF6 and n‐Hx4NPF6, whose marginal inclusion inside the film channels promotes both the entrance of ferrocene and the expelling of ferrocenium ions from these ones. This phenomenon was emulated through a CEC mechanism in solution, where the diffusion inside the channels was described as single chemical equilibria.

Bioelectrochemical remediation of phenanthrene in a microbial fuel cell using an anaerobic consortium enriched from a hydrocarbon-contaminated site

Polycyclic aromatic hydrocarbons (PAH) are organic pollutants that require remediation due to their detrimental impact on human and environmental health. In this study, we used a novel approach of sequestering a model PAH, phenanthrene, onto a solid carbon matrix bioanode in a microbial fuel cell (MFC) to assess its biodegradation coupled with power generation. Here, the bioanode serves as a site for enrichment of electroactive and hydrocarbon-degrading microorganisms, which can simultaneously act to biodegrade a pollutant and generate power. Carbon cloth electrodes loaded with two rates of phenanthrene (2 and 20 mg cm−2) were compared using dual chamber MFCs that were operated for 50 days. The lower loading rate of 2 mg cm−2 was most efficient in the degradation of phenanthrene and had higher power production capacities (37 mW m−2) as compared to the higher loading rate of 20 mg cm−2 (power production of 19.2 mW m−2). FTIR (Fourier-Transform Infrared Spectroscopy) analyses showed a depletion in absorbance peak signals associated with phenanthrene. Microbes known to have electroactive properties or phenanthrene biodegradation abilities like Pseudomonas, Rhodococcus, Thauera and Ralstonia were enriched over time in the MFCs, substantiating the electrochemical and FTIR analyses. The MFC approach taken here thus offers great promise towards PAH bioelectroremediation.

Polymorphism, dielectric and piezoelectric response of organo-modified Ni–Co layered double hydroxide nanosheets dispersed electrospun PVDF nanofabrics

Poly(vinylidene fluoride) (PVDF) with excellent flexibility and electroactive properties is a promising material for energy harvesting. In this study, organically modified Ni–Co layered double hydroxide (OLDH) was synthesized and the nanosheets of this OLDH were used as filler in electrospun PVDF nanofabrics. Morphology, crystallinity, dielectric, and piezoelectric properties of the electrospun nanofabrics were characterized. Presence of OLDH in PVDF nanofabrics led to enhancement of polar β-phase in the latter, which was corroborated from the results of Fourier transform infrared spectroscopy and X-ray diffraction. Dielectric constant of the nanofabrics tends to increase with OLDH content, while the corresponding dielectric loss remained low. An indigenously designed nanogenerator from these nanofabrics exhibited a maximum output voltage of 6.9 V and power density of 0.92 μW/cm2 under human finger tapping mode at 3 wt% loading of OLDH. The synergistic effect of OLDH and electrospinning contributed to the enhancement of the β-phase content, thereby the piezoelectric response of the composite nanofabrics. The demonstrated nanogenerator could possibly power flexible and portable electronic devices.

Effect of Na+ MMT-ionic liquid synergy on electroactive, mechanical, dielectric and energy storage properties of transparent PVDF-based nanocomposites

Transparent dielectric composites with high electroactive, low dielectric loss and high energy density are highly desirable due to the potential applications in electronic and electric industry. In this work, simultaneously achieving excellent electroactive, high dielectric and energy storage performance in a transparent dielectric composite is proposed by compounding nano-montmorillonite (Na+ MMT) and ionic liquid (IL) with poly (vinylidene fluoride) (PVDF) through one-step melt blending technique. The microstructure, crystal forms, transparency, mechanical, dielectric and energy storage performances of PVDF/MMT/IL nanocomposites were systematically investigated. The existence of IL and shearing force contributes to the effective exfoliation of MMT in the PVDF matrix. Based on the synergy of Na+ MMT and IL, the PVDF/IL/MMT composites not only exhibited almost 100% polar phase PVDF but also the optical transmittance was significantly enhanced. The improved dielectric constant and reduced dielectric loss were successfully achieved in the PVDF/IL/MMT nanocomposites due to the inhibition of ion migration by exfoliated silicate layers. Moreover, the PVDF/IL/MMT nanocomposite exhibited improved energy storage performance compared with the nanocomposites containing IL or Na+ MMT independently. Therefore, the PVDF/IL/MMT nanocomposite with high electroactive, excellent transparency, high dielectric and energy storage performance shows potential applications in microelectronic device.

Electrospun fibers for biomimetic applications

Electrospinning represent a “classic” technique to obtain micrometer and sub micrometer fibers for a wide range of applications. The technique is relatively simple and allows the preparation of industrial amounts of material with low cost. A polymer solution droplet is exposed to an intense electric field which leads to the formation of a jet and further to a very thin fiber of the polymer. Functionalization represents a step which can tremendously increase the range of applications of these thin fibers. Therefore our aim was to test several paths towards new and more complex architectures. In the present report we will describe our work regarding functionalized biocompatible fiber arrays based on a set of preparation methods which start with electrospinning. In order to achieve the desired functionality sputtering of a thin metal layer leads to conductive fibers. We used these as working electrodes for electrochemical deposition and the fibers were covered with polymers such as polyaniline[1,2] or with ZnO. The sequence of steps enabled us to obtain mats with either electroactive properties or with photocatalytic activity. Both these properties are very interesting for applications ranging from artificial muscles to substrates with antimicrobial activity. The straightforward, scalable methods of fabrication make the approach a very interesting one for lucrative applications.