Electroactive Materials Research Articles

Sensing, Imaging, and Therapeutic Strategies Endowing by Conjugate Polymers for Precision Medicine.

Conjugated polymers (CPs) have promising applications in biomedical fields, such as disease monitoring, real-time imaging diagnosis, and disease treatment. As a promising luminescent material with tunable emission, high brightness and excellent stability, CPs are widely used as fluorescent probes in biological detection and imaging. Rational molecular design and structural optimization have broadened absorption/emission range of CPs, which are more conductive for disease diagnosis and precision therapy. This review provides a comprehensive overview of recent advances in the application of CPs, aiming to elucidate their structural and functional relationships. The fluorescence properties of CPs and the mechanism of detection signal amplification are first discussed, followed by an elucidation of their emerging applications in biological detection. Subsequently, CPs-based imaging systems and therapeutic strategies are illustrated systematically. Finally, recent advancements in utilizing CPs as electroactive materials for bioelectronic devices are also investigated. Moreover, the challenges and outlooks of CPs for precision medicine are discussed. Through this systematic review, it is hoped to highlight the frontier progress of CPs and promote new breakthroughs in fundamental research and clinical transformation.

Zero‐Dimensional Carbon Nanomaterials for Electrochemical Energy Storage

AbstractProgress in research on high‐performance electrochemical energy storage devices depends strongly on the development of new materials. The 0‐dimensional carbon nanomaterials (fullerenes, carbon quantum dots, graphene quantum dots, and “small” carbon nano‐onions) are particularly recognized in this area of research. Their unique properties beneficial for batteries and supercapacitors application are the result of their small and controllable size, ranging from 1 to 10 nm, and their structure. Fullerenes stand out for the particularly precise structure and rich redox properties. Carbon‐based quantum dots and “small” carbon nano‐onions provide a bridge between molecular fullerenes and larger nanostructured carbon systems. For the electrochemical energy storage, 0‐dimensional carbon structures are usually present in nanostructured composites, which ensure high efficiency of devices. In this review, issues related to the contribution of 0‐dimensional carbon materials in improving batteries and supercapacitors. Particular attention has been paid to progress resulting from the use of composites of these carbon nanostructures with other electroactive materials. Much attention has also been devoted to issues related to the synthesis of 0‐dimensional carbon nanostructures enabling the control of their size, chemical composition and surface morphology. Finally, issues requiring additional research are highlighted.

Manipulation of Surface Electrical Charge on Nanocomposite Membranes Confers Wide Spectrum Bactericidal Effects and Promotes Tissue Regeneration

AbstractUtilization of electro‐responsive biomaterials with antibacterial properties is advantageous for facilitating septic wound healing and tissue regeneration. However, the dose‐response effects of electrical stimuli from these materials against bacteria are not rigorously characterized, and achieving synergy of bactericidal and pro‐regenerative effects of biomaterials remains a major challenge. Here, a graded series of flexible BaTiO3/P(VDF‐TrFE) electroactive nanocomposite membranes (EMs) are developed with varying surface charge intensities, to serve as antibacterial dressing for septic wound healing. EMs display broad‐spectrum antibacterial effects against both Gram‐positive and Gram‐negative bacteria in a dose‐dependent manner, depending on the magnitude of their surface electrical potential. Mechanistically, the surface charge of EMs increase intracellular levels of reactive oxygen species within bacteria cells, which in turn caused oxidative damage to the bacterial membrane, thereby suppressing bacterial activity and biofilm formation. Moreover, in vivo studies demonstrated that EMs effectively inhibited S. aureus infection and accelerated wound healing in a mouse skin defect model, as well as ameliorated P. gingivalis‐mediated periodontal inflammation in a mouse periodontitis model. Hence, this study optimizes the antibacterial properties of electroactive materials and characterizes the dose‐response effects of surface electrical charge against bacteria, thus validating the therapeutic applications of electroactive biomaterials in combating bacterial infection.

WS2/Mesoporous Carbon Nanostructures as a Bifunctional Electrode for All Quasi‐Solid‐State Supercapacitor and Oxygen Evolution Reaction

Abstract2D transition‐metal sulfides have developed as favorable electroactive materials for electrochemical energy storage and conversion applications. In this work, WS2/mesoporous carbon (MC) is developed by a one‐step hydrothermal technique for supercapacitor and oxygen evaluation reaction (OER) application. However, the metal sulfides have poor rate and cyclic performance due to the aggregations between two layers of structures restricting their performance. The interaction between WS2 nanosheets and MC produces a synergistic effect, resulting in a decent electrochemical energy storage and conversion application. The synthesized materials used to prepare quasi‐solid‐state symmetric (QSSS) and asymmetric (QSSA) supercapacitor configuration enable the highest specific capacitance (CSP) of 305.45 F g−1 and 204.21 F g−1@ 10 mV s−1, respectively. Moreover, the specific energy and power density of QSSS and QSSA devices are 31.1 Wh kg−1 @824.95 W kg−1 and 24.74 Wh kg−1 @549.84 W kg−1, respectively. Additionally, the multifunctionality of the synthesized binary nanocomposite is also tested for OER. The composite shows a desirable over potential of 307 mV in 6 m KOH electrolyte, with a 69 mV dec−1 Tafel slope. The dual role of WS2/MC for energy storage and oxygen evaluation reaction conversion reveals the potential of metal sulfides.

Aggregation and Capacity Limiting Effects in Anthraquinone-Based Flow Battery Negolytes

Anthraquinone-based molecules are promising electroactive materials for use in aqueous organic flow batteries. At high concentrations in aqueous solutions, the well-known negolyte molecule anthraquinone disulfonic acid (AQDS) molecule has been observed to aggregate under near-neutral and acidic conditions. Aggregation has been hypothesized to be directly linked to observed concurrent capacity reduction. In this study, we investigated three different water-soluble anthraquinones in electrolytes of varying compositions and pH to gain further insight into the possible causes of capacity loss. We used low-field benchtop 1H-NMR and diffusion NMR measurements directly in non-deuterated aqueous flow-battery electrolytes to investigate molecular aggregation. Single-cell testing was performed under exhaustive electrolysis conditions to determine the number of electrons exchanged per molecule. We observed a decrease in the number of electrons exchanged per molecule in the presence of carbonate ions due to CO2 adduct formation. The aggregation constants were determined from both concentration-dependent chemical shifts and self-diffusion coefficients. We show that aggregation of the oxidized form of all three molecules studied here occurs under near-neutral and alkaline conditions and does not affect the number of accessible e−.

Fusion Position-Dependent Aromatic Transitions of Ligand Backbone Rings for Controlling the Redox Energetics of Photoredox Catalysts.

To reveal, quantify, and rationalize the effect of backbone π-extension on ligand redox activity, we studied the ground- and excited-state reduction potentials of eight ruthenium photoredox catalysts with the formula Ru(ppy)2L (L is the redox-active ligand of the bipyridine family) using density functional theory. Our research underlines the profound importance of the fusion position of backbone aromatic C6 rings on the redox activity of ligands in transition metal photoredox catalysts. Namely, certain fusion positions lead to the dearomatization of C6 rings in ligand-centered electron transfer events, resulting in a thermodynamic penalty equivalent to a half-volt negative shift in the reduction potential. Contrarily, the extent of backbone delocalization shows a minimal impact on redox energetics, which can be explained by the charge concentration at the nitrogen contact atoms in ligand-centered reductions. Grounded in Caulton's conceptual framework, we reaffirm the predictive potency of Lewis structures in ligand-centered redox energetics with qualitative and quantitative data. Our hypothesis regarding the effect of backbone ring dearomatization on redox energetics is further corroborated using magnetic and structure-based aromaticity indicators. Highlighting fusion-dependent dearomatization as a determining factor of ligand-centered electron transfer energetics, our findings hold implications for molecular-level design in advanced electroactive materials and catalysts.

Effective assembling of nickel oxide-reduced graphene oxide heterostructures for ultrahigh capacity supercapattery

Developing new materials to facilitate sustainable and renewable energy storage is the most sought research frontier of the current era. In this regard, supercapacitors have drawn huge research attention in developing efficient electroactive materials. Herein, a nickel oxide/reduced graphene oxide (NiO-rGO) composite has been synthesized using the facile precipitation-aging-calcination and ultrasonication technique for energy storage applications. Due to the composite's enhanced surface area and the synergistic effect of redox-active NiO and highly conductive rGO, the resulting heterostructure exhibits excellent performance as a supercapattery. The electrochemical investigations show that the designed NiO-rGO heterostructure exhibits battery-type electrode features with an ultrahigh specific capacity of 850 Cg-1 at 1 Ag-1 current density with 91 % capacity retention even after 5000 charge-discharge cycles. The efficacy of this composite has also been tested in a symmetrical device assembly (NiO-rGO//NiO-rGO), which shows a very high maximum energy density (56.6 Wh.kg−1) and power density (9.65 kW kg−1) with excellent performance retention for 10000 charge/discharge cycles. Further, the experimental charge storage outcomes of the materials have also been supported by calculating the energetics of OH* adsorption using DFT. This work provides a facile approach to maximize the synergistic interactions within metal oxides-rGO-based 3D/2D heterostructures to derive improved electrochemical features. Moreover, it also offers experimental and theoretical insights into designing efficient and cost-effective materials for energy storage.

Redox-Active Organic Materials: From Energy Storage to Redox Catalysis.

Electroactive materials are central to myriad applications, including energy storage, sensing, and catalysis. Compared to traditional inorganic electrode materials, redox-active organic materials such as porous organic polymers (POPs) and covalent organic frameworks (COFs) are emerging as promising alternatives due to their structural tunability, flexibility, sustainability, and compatibility with a range of electrolytes. Herein, we discuss the challenges and opportunities available for the use of redox-active organic materials in organoelectrochemistry, an emerging area in fine chemical synthesis. In particular, we highlight the utility of organic electrode materials in photoredox catalysis, electrochemical energy storage, and electrocatalysis and point to new directions needed to unlock their potential utility for organic synthesis. This Perspective aims to bring together the organic, electrochemistry, and polymer communities to design new heterogeneous electrocatalysts for the sustainable synthesis of complex molecules.

Utilization of anthracite as electroactive material in sodium-ion batteries

Utilization of anthracite as electroactive material in sodium-ion batteries

Elucidating the role of La2NiO4±δ (LNO) nanoparticles in modulating chromium poisoning in LSM air electrodes of solid oxide cells: A study on oxygen reduction and evolution reactions

As the solid oxide cells (SOCs) are becoming durable, their air electrode materials require investigation for their tolerance against chromium (Cr) poisoning. Herein, La2NiO4±δ (LNO), a highly electroactive and nucleation agent-free material, is infiltrated into the (La,Sr)MnO3-δ (LSM) backbone to diagnose its' influence on the Cr-poisoning of LSM. While the non-impregnated LSM's degrades by Cr contaminant, LNO-infiltrated LSM (LSM.LNO) shows less sensitivity to Cr presence specifically during the electrolysis mode. LNO's presence inhibits the formation of detrimental phases at the electrode/electrolyte interface during the anodic polarization in Cr-containing ambient. Moreover, surface promotion by LNO nanoparticles reduces, but not inhibits, the formation of undesirable phases during the cathodic polarization in the Cr presence. According to the electrodes' overpotential trends, the electrochemical impedance spectroscopy (EIS) responses in addition to the distribution of the relaxation times (DRT) analysis, the presence of Cr alters the LSM.LNO's electrochemical characteristics via reacting with the nanoparticles. As the XRD analysis proves, LaCrO3 formation on the LNO nanoparticles' surface gradually decays the LSM.LNO's cathodic performance. However, LNO's higher activity for oxygen evolution than oxygen reduction reaction accompanied by slower LNO/Cr reaction kinetics during anodic polarization improve and stabilize the LSM.LNO's anodic performance in Cr-containing environment.

Synthesis of a Photo‐Crosslinkable Elastomer for Stretchable Electronics and Its Use in Strain‐Insensitive Pressure Sensors

AbstractA stretchable electronic substrate with strategically positioned rigid and soft islands offers a significant platform to overcome the limitations of current stretchable substrates. This design facilitates the integration of conventional rigid electroactive materials into high‐performance stretchable electronics. This study introduces a photo‐crosslinkable, transparent elastomer substrate based on acrylates. When exposed to UV irradiation, it undergoes selective crosslinking (with crosslinking density and modulus depending on the number of crosslinkers); it can achieve a modulus increase of up to 38 000%. Rigid regions of specific shapes and sizes can be created using a photomask, while soft regions remain intact for expansion during stretching. The substrate is used to produce a capacitive strain/strain‐insensitive pressure (SIP) sensor in which rigid islands act as the dielectric layer of the capacitor; sensitivity to external stimuli is modulated by the modulus of the rigid islands. In addition, a high‐efficiency SIP sensor (SIPS) employing an electrospun dielectric layer, which amplifies the pressure sensitivity by 780‐fold, is developed, ensuring a constant low strain sensitivity.

Piezoelectric Nanomaterial‐Mediated Physical Signals Regulate Cell Differentiation for Regenerative Medicine

Tissue damage often causes considerable suffering to patients due to slow recovery and poor prognosis. The use of electroactive materials to deliver biophysical signals plays a key role in regulating tissue regeneration processes. Among these materials, piezoelectric materials have unique electromechanical conversion capabilities, making them suitable for use as cell scaffolds. They can deform and emit electrical signals in response to external stimuli, thereby regulating cell proliferation and differentiation. In this review, recent advances are presented in piezoelectric materials as physical signaling mediators that regulate cell differentiation. The basic mechanisms, classification of these materials, and their different applications in tissue regeneration are described. Finally, a comprehensive discussion of current challenges and prospects in the field is provided. Together, existing experimental results basically show that piezoelectric materials can improve the process and effect of tissue repair, providing new technical options for the development of tissue engineering in the future.

Electroactive Biomaterials Regulate the Electrophysiological Microenvironment to Promote Bone and Cartilage Tissue Regeneration

AbstractThe incidence of large bone and articular cartilage defects caused by traumatic injury is increasing worldwide; the tissue regeneration process for these injuries is lengthy due to limited self‐healing ability. Endogenous bioelectrical phenomenon has been well recognized to play an important role in bone and cartilage homeostasis and regeneration. Studies have reported that electrical stimulation (ES) can effectively regulate various biological processes and holds promise as an external intervention to enhance the synthesis of the extracellular matrix, thereby accelerating the process of bone and cartilage regeneration. Hence, electroactive biomaterials have been considered a biomimetic approach to ensure functional recovery by integrating various physiological signals, including electrical, biochemical, and mechanical signals. This review will discuss the role of endogenous bioelectricity in bone and cartilage tissue, as well as the effects of ES on cellular behaviors. Then, recent advances in electroactive materials and their applications in bone and cartilage tissue regeneration are systematically overviewed, with a focus on their advantages and disadvantages as tissue repair materials and performances in the modulation of cell fate. Finally, the significance of mimicking the electrophysiological microenvironment of target tissue is emphasized and future development challenges of electroactive biomaterials for bone and cartilage repair strategies are proposed.

In-situ grown nickel iron bimetal organic frameworks from activated Ni foam for efficient energy storage and electrocatalysis: Study of metal ratio and nickel precursor effects

Ex-situ fabrication of electroactive electrodes encounters serious peeling off problems. Nickel foam (NF) shows promise as conductive substrate of electroactive electrodes due to high surface area, porosity and conductivity. To broaden NF applications and enhance attachments, applying in-situ growth for establishing efficient active materials on NF is necessary. In this study, nickel iron bimetal organic frameworks (NiFeMOF) are firstly synthesized from activated NF as electroactive electrodes for energy storage and electrocatalysis. Metal ratio and nickel precursor effects are studied to elucidate growing mechanism of electroactive materials. The optimal NiFeMOF/NF presents the highest specific capacitance (CF) of 2017.9 F/g at 20 mV/s, while MOF/NF electrodes prepared with only Ni and Fe respectively show smaller CF values of 622.1 and 1121.8 F/g. The superior electrocatalytic ability is achieved by NiFeMOF/NF. Inclusion of additional Ni salts is necessary for synthesizing Ni-MOF on NF with improved energy storage ability, but that prepared without addition of Ni salt exhibits better electrocatalytic ability. Trade-off between electrochemical surface area and electrical conductivity is proved as crucial factor in designing electroactive materials for energy storage and electrocatalytic water splitting. This study brings novel insights into establishment of effective electroactive materials for electrochemical systems using simple concepts and techniques.

Energy-Efficient Nanostructured Ion Exchange Membranes from Functionalized Poly (2,6-Dimethyl-1,4-Phenylene Oxide)

Highly energy efficient and ion permeable ion exchange membranes are in high demand in many modern sectors to clean water, transform energy, and store energy in devices like electro-dialyzer, fuel cells, and batteries. However, greater resistance and reduction in ion permeation of conventional membranes dictate the desire for nanostructured functional ion exchange membranes. This project proposes the fabrication of ion exchange membranes using electroactive nanostructured polyaniline incorporation into ion exchange materials, electrostatically interaction between polymer and nanostructured electroactive material overcomes the problem of high resistance and less ion permeation. Solution casting and post-drying techniques are used for membrane casting. Nanostructured electroactive material helps to increase ionic conduction thus reducing 17% resistance for functional cation exchange membrane (FCEM) and 12% for functional anion exchange membrane (FAEM) also assisting to increase ion permeation. Hydrophilic nanostructured polyaniline electroactive material holds more water and increases water uptake. Cross-linking increases stability as well as reduces 17% and 8% swelling degrees for FCEM and FAEM respectively. Besides the electrochemical property offers an increase limiting current density of 38%, 23% for FCEM and FAEM respectively, and 19% higher desalination performance than non-nanostructured sulfonated polyphenylene oxide (CEM) and quaternized polyphenylene oxide (AEM) membranes.

Mapping the nanoscale elastic property modulations of polypyrrole thin films in liquid electrolyte with EC-AFM.

Linking structure to mechanical and elastic properties is a major concern for the development of novel electroactive materials. This work reports on the potential-induced changes in thickness and Young modulus of a substrate supported, perchlorate doped polypyrrole thin film (<100 nm) investigated with electrochemical atomic force microscopy (AFM) under in situ conditions. This was accomplished by nanomechanical mapping of potentiodynamically electropolymerized polypyrrole film in electrolyte solution with AFM during redox cycling. The polypyrrole film thickness and Young modulus follow the electrical potential nearly linearly, increasing due to solvent and ion influx as the film is oxidized, and decreasing during reduction. Our measurements also confirm the presence of a potential-independent, passive swelling which is accompanied by softening of the film, likely caused by osmotic effects. Additionally, the heterogeneous distribution of the Young modulus can be directly traced to the typical nodular surface topography of polypyrrole, with the top of the nodular area possessing lower modulus, thus highlighting the complex relationship between topography and elastic properties.

Modification of carbon nanofibers for boosting oxygen electrocatalysis.

Oxygen electrocatalysis is a key process for many effective energy conversion techniques, which requires the development of high-performance electrocatalysts. Carbon nanofibers featuring good electronic conductivity, large specific surface area, high axial strength and modulus, and good resistance toward harsh environments have thus been recognized as reinforcements in oxygen electrocatalysis. This review summarizes the recent progress on carbon nanofibers as electrocatalysts for oxygen electrocatalysis, with special focus on the modulation of carbon nanofibers for further elevating their electrocatalytic performance, which includes morphological and structural engineering, surface and pore size distribution, defect engineering, and coupling with other electroactive materials. Additionally, the correlation between the geometrical/electronic structure of their active centers and electrocatalytic activity is systematically discussed. Finally, conclusions and perspectives of this interesting research field are presented, which we hope will provide guidance for the future fabrication of more advanced carbon-fiber-based electrocatalysts.

Thermodynamic model for voltammetric responses in conducting redox polymers.

Electroactive polymer materials are known to play important roles in a vast spectrum of modern applications such as in supercapacitors, fuel cells, batteries, medicine, and smart materials, etc. They are usually divided into two main groups: first, conducting π-conjugated organic polymers, which conduct electricity by cation-radicals delocalized over a polymer chain; second, redox polymers, which conduct electricity via an electron-hopping mechanism. Polymer materials belonging to these two main groups have been thoroughly studied and their thermodynamic and kinetic models have been built. However, in recent decades a lot of mixed-type materials have been discovered and investigated. To the best of our knowledge, a thermodynamic-based description of conducting redox polymers (CRPs) has not been provided yet. In this work, we present a thermodynamic model for voltammetric responses of conducting redox polymers. The derived model allows one to extract thermodynamic parameters of a CRP including the polaron delocalization degree and redox active groups interaction constant. The model was verified with voltammetric experiments on three recently synthesized CRPs and showed a satisfactory predictive ability. The simulated data are in good agreement with the experiment. We believe that developing theoretical descriptions for CRPs and other types of electroactive materials with the ability to simulate their electrochemical responses may help in future realization of new systems with superior characteristics for electrochemical energy storage, chemical sensors, pharmacological applications, etc.

Electroactive sulfur-rich materials obtained via inverse vulcanization of a diallylsilyl-functionalized ferrocene

Redox-responsive polysulfide materials, synthesized via inverse vulcanization, exhibit a synergistic ferrocene–sulfur effect, evidenced by their ability to electrochemically detect environmental hazardous Hg2+ and Cd2+ cations.

Organic electrodes based on redox-active covalent organic frameworks for lithium batteries.

Electroactive organic materials have received much attention as alternative electrodes for metal-ion batteries due to their high theoretical capacity, resource availability, and environmental friendliness. In particular, redox-active covalent organic frameworks (COFs) have recently emerged as promising electrodes due to their tunable electrochemical properties, insolubility in electrolytes, and structural versatility. In this Highlight, we review some recent strategies to improve the energy density and power density of COF electrodes for lithium batteries from the perspective of molecular design and electrode optimisation. Some other aspects such as stability and scalability are also discussed. Finally, the main challenges to improve their performance and future prospects for COF-based organic batteries are highlighted.