Effects of synthetic conditions of pulse galvanostatic method on electroactivity of polyaniline

Nano-fibrous polyaniline was synthesized on stainless steel electrode in 0.5mol·L-1 H2SO4 solution by pulse galvanostatic method. The effects of synthetic conditions of pulse galvanostatic method on the electroactivity of polyaniline were investigated. The results show that the electroactivity of polyaniline film strongly depends on the synthetic conditions, such as the ratio of “on time” to “off time”(ton/toff), frequency, monomer concentration, temperature and mean current density. Different electroactivities of polyaniline are caused by different morphologies of polyaniline. The nano-fibrous polyaniline has higher electroactivity than polyaniline with other morphologies. Under the following conditions: mean current density of pulse galvanostatic method 13mA·cm-2, ton/toff 1, frequency 200Hz, monomer concentration 0.3mol·L-1 and temperature 20℃, nano-fibrous polyaniline film with the highest electroactivity can be obtained.

Recent strategies to improve the electroactivity of metal-organic frameworks for advanced electrocatalysis

Metal-organic frameworks(MOFs)have emerged as promising materials in the realm of electrocatalysis due to their high surface area,tunable porosity,and versatile chemical functionality.However,their practical application has been hampered by inherent limitations such as low electrical conductivity and a limited number of active metal sites.Researchers addressed these challenges through various strategies,including enhancing conductivity by incorporating conductive materials and metal nanoparticles,modifying the structure and composition of MOFs by replacing metal nodes and functionalizing linkers,and preparing MOFs catalysts through thermal processes such as decarburization and con-version into metal oxides,phosphides(MPs),and sulfides(MSs).This review provided a comprehensive summary of the strategies that were employed to enhance the electroactivity of MOFs for improved electrocatalytic performance in recent years.It also explored future directions and potential innovations in the design and synthesis of MOF‐based electrocatalysts,offering valuable insights for advancing their application in sustainable energy technologies.

Compositional engineering of HKUST-1/sulfidized NiMn-LDH on functionalized MWCNTs as remarkable bifunctional electrocatalysts for water splitting

Water-splitting reactions such as the hydrogen evolution reaction(HER)and the oxygen evolution reaction(OER)typically require expensive noble metal-based electrocatalysts.This has motivated researchers to develop novel,cost-effective electrocatalytic systems.In this study,a new multicomponent nanocomposite was assembled by combining functionalized multiwalled carbon nanotubes,a Cu-based metal–organic framework(MOF)(HKUST-1 or HK),and a sulfidized NiMn-layered double hydroxide(NiMn-S).The resulting nanocomposite,abbreviated as MW/HK/NiMn-S,features a unique architecture,high porosity,numerous electroactive Cu/Ni/Mn sites,fast charge transfer,excellent structural stability,and conductivity.At a current density of 10 mA cm-2,this dual-function electrocatalyst shows remarkable performance,with ultralow overpotential values of 163 mV(OER)or 73 mV(HER),as well as low Tafel slopes(57 and 75 mV dec-1,respectively).Additionally,its high turnover frequency values(4.43 s-1 for OER;3.96 s-1 for HER)are significantly superior to those of standard noble metal-based Pt/C and IrO2 systems.The synergistic effect of the nanocomposite's different components is responsible for its enhanced electrocatalytic performance.A density functional theory study revealed that the multi-interface and multicomponent heterostructure contribute to increased electrical conductivity and decreased energy barrier,resulting in superior electrocatalytic HER/OER activity.This study presents a novel vision for designing advanced electrocatalysts with superior performance in water splitting.Various composites have been utilized in water-splitting applications.This study investigates the use of the MW/HK/NiMn-S electrocatalyst for water splitting for the first time to indicate the synergistic effect between carbon-based materials along with layered double hydroxide compounds and porous compounds of MOF.The unique features of each component in this composite can be an interesting topic in the field of water splitting.

Hydrothermal Synthesis of V₃O₇.^.H₂O Nanobelts and Study of Their Electrochemical Properties

Vanadium oxide hydrate V3O7..H2O (H2V3O8) nanobelts have been synthesized by hydrothermal approach using V2O5 as vanadium source and phenolphthalein as structure-directing agent. Techniques X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy and nitrogen adsorption/desorption isotherms have been used to characterize the structure, morphology and composition of the nanobelts. The V3O7. H2O nanobelts are up to several hundreds of nanometers, the widths and thicknesses are 90 and 40 nm, respectively. The electroactivity of the nanobelts has been investigated. The as-synthesized material is promising for chemical and energy-related applications such as catalysts, electrochemical device and it may be applied in rechargeable lithium-ion batteries.

Biomedical Perspective of Electrochemical Nanobiosensor

Electrochemical biosensor holds great promise in the biomedical area due to its enhanced specificity, sensitivity, label-free nature and cost effectiveness for rapid point-of-care detection of diseases at bedside. In this review, we are focusing on the working principle of electrochemical biosensor and how it can be employed in detecting biomarkers of fatal diseases like cancer, AIDS, hepatitis and cardiovascular diseases. Recent advances in the development of implantable biosensors and exploration of nanomaterials in fabrication of electrodes with increasing the sensitivity of biosensor for quick and easy detection of biomolecules have been elucidated in detail. Electrochemical-based detection of heavy metal ions which cause harmful effect on human health has been discussed. Key challenges associated with the electrochemical sensor and its future perspectives are also addressed.

Ionic Elastomers for Electric Actuators and Sensors

In the past decades,ion conductive polymers and elastomers have drawn worldwide attention for their advanced functions in batteries,electroactive soft robotics,and sensors.Stretchable ionic elastomers with dispersed soft ionic moieties such as ionic liquids have gained remarkable attention as soft sensors,in applications such as the wearable devices that are often called electric skins.A considerable amount of research has been done on ionic-elastomer-based strain,pressure,and shear sensors;however,to the best of our knowledge,this research has not yet been reviewed.In this review,we summarize the materials and performance properties of engineered ionic elastomer actuators and sensors.First,we review three classes of ionic elastomer actuators—namely,ionic polymer metal composites,ionic conducting polymers,and ionic polymer/carbon nanocomposites—and provide perspectives for future actuators,such as adaptive four-dimensional(4D)printed systems and ionic liquid crystal elastomers(iLCEs).Next,we review the state of the art of ionic elastomeric strain and pressure sensors.We also discuss future wearable strain sensors for biomechanical applications and sports performance tracking.Finally,we present the preliminary results of iLCE sensors based on flexoelectric signals and their amplification by integrating them with organic electrochemical transistors.

SOLID STATE VOLTAMMETRY OF ELECTROACTIVE SOLUTES IN POLYMER SOLVENTS(PEO)AT MICROELECTRODE

The present paper describes experiments aimed at delineating significant chemical characteristics of electrochemical reactions in polymeric solutions, including how rigid solvent environments affect mass transport rates, and also discusses the possibility that the microelectrode coated with poly(ethylene oxide)(PEO) film can be used as gas sensor.

Physical Diffusion and Electron-transfer Dynamics of Electroactive Solutes in Polymer Electrolytes Ⅲ. Effect of the Polymer Solvents

The diffusion coefficients(Dapp) and the heterogeneous electron transfer rate constants(ks)for ferrocene in several polymer solvents were determined by using steady-stae voltammetry. Thetemperature dependence of the two parameters indicates Arrhenius behavior. The polymer solventeffects on diffusion and electron transfer dynamics of ferrocene were discussed

Microbial Electrosynthesis for Producing Medium Chain Fatty Acids

Microbial electrosynthesis(MES)employs microbial catalysts and electrochemistry to enhance CO_(2)bioconversion to organics with concurrent waste biorefining capability.The aim of this review is to comprehensively discuss the current state of the art and prospects of medium chain fatty acids(MCFAs)production in MES from CO_(2)and organic wastes.Fundamental mechanisms and development of MCFAs production via conventional fermentation are introduced as well.Studies on MCFAs production in MES are summarized,highlighting the strategy of multiple-electron donors(EDs).Challenges for MCFAs production in MES from CO_(2)are presented,and the primary discussions included methanogenesis inhibition,adenosine triphosphate(ATP)limitations of acetogens,and production of limited EDs via solventogenesis.Possible applications of electrochemical approaches to promote the bioconversion of actual waste materials with MCFAs production are analyzed.Finally,future directions are explored,including multi-stage reactions,substrate supply,product extraction,and microbial pathways.

Electroactive species study in the electrochemical reduction of CO_2 in KHCO_3 solution at elevated temperature

Photoelectrochemical and electrochemical reduction of CO_2 into organic chemicals is promising for directly or indirectly transforming solar energy into chemical energy for further utilization. However,research on the electroactive species in these processes has been rather limited. In this work, we investigated possible electroactive species(CO_2 or HCO_3~– ) involved in the electrochemical reduction of KHCO_3 at elevated temperatures without CO_2 bubbling. The results showed that CO, CH_4, and C_2H_4 were produced after electrochemical reduction of 3.0 mol/L KHCO_3 at elevated temperature on a Cu electrode even without CO_2 bubbling, although their faradaic efficiencies were low(< 6 %). Measurements for CO_2 generation from the decomposition of HCO_3~– showed that elevated temperature and high HCO_3~– concentration strongly promoted this process. These results suggested that the in-situ produced CO_2 from the decomposition of HCO_3~– was probably the electroactive species in the electrochemical reduction of HCO_3~– without CO_2 bubbling. Changes of the Gibbs free energy, rate constant, and activation energy of the decomposition of HCO_3~– into CO_2 were also investigated and calculated from the experimental data.

Indentation of a compressible soft electroactive half-space: Some theoretical aspects

We theoretically study the indentation response of a compressible soft electroactive material by a rigid punch. The half-space material is assumed to be initially subjected to a finite deformation and an electric biasing field. By adopting the linearized theory for incremental fields, which is established on the basis of a general nonlinear theory for electroelasticity, the appropriate equations governing the perturbed infinitesimal elastic and electric fields are derived particularly when the material is subjected to a uniform equibiaxial stretch and a uniform electric displacement. A general solution to the governing equations is presented, which is concisely expressed in terms of four quasi-harmonic functions. By adopting the potential theory method, exact contact solutions for three common perfectly conducting rigid indenters of fiat-ended circular, conical and spherical geometries can be derived, and some explicit relations that are of practical importance are outlined.

A NEW APPROACH TO ELECTROACTIVE POLYMERS VIA WELL-DEFINED OLIGOMERRS WITH FURTHER POLYMERIZABLE END-GROUPS

Among the inherent drawbacks of conducting polymers are the limited processibility, uneven polydispersity inmolecular weigh and the existence of structure defects, which become the obstacles for many electronic, optical andbiological applications that demand the materials to have well-defined structures and high chemical purity. To solve theseproblems, our research in the last decade or so has focused on the synthesis of electroactive oligomers of well-definedstructures, controllable molecular weighs, narrow or uniform polydispersity. We have developed a general strategy for thesynthesis of such oligomers based on the theory of non-classical or reactivation chain polymerization. The aniline oligomerswith minimum 4 nitrogen atoms and 3 phenylene rings exhibit similar characteristic redox behavior and electroactivity aspolyaniline. Electronic conductivity of the oligomers of 7 or 8 aniline units approaches that of polyaniline. Solubility of theoligomers is much improved over that of conventional polyaniline. Various functional groups can be introduced into theoligomers either by proper selection of starting materials or by post-synthesis modifications via common organic reactions.The functionalized oligomers undergo further polymerizations to afford a variety of new electroactive materials, includingpolyamides, polyimides, polyureas, polyurethanes, polyacrylamides and epoxy polymers. Numerous potential applications,particularly as anticorrosion materials, are discussed for the oligomers and their polymeric derivatives.

Electroactive soft materials with high stretchability and transparency

Nowadays,with the rapid development of wearable devices,more and more electroactive soft materials have approached to the scene view of human and flexible polymer materials are the most widely studied in this field[1-5].These materials can be applied in soft robotics,sensors,batteries and so on[6-8].However,flexible polymer materials have some drawbacks.For example,as the most common flexible ionic conductors,hydrogels cannot bear extreme temperatures and they have terrible stability in air environment.These flaws result in their short service life.And the classical dielectric materials VHB need high driving voltage,so there is a strong risk in applications[9-10].Therefore,existing flexible polymer materials cannot be large-scale used.

Physical Diffusion and Electron-transfer Dynamics of Electroactive Solutes in Polymer Electrolytes Ⅰ. Effect of the Nature of Electroactive Solutes

The diffusion coefficients(Dapp) and the heterogeneous electron-transfer rate constants(ks)for ferrocene and its seven derivatives in MPEG/LiClO4 electrolyte were determined by using steadystate voltammetry. The two parameters increase with increasing temperature, indicating Arrhenius behavior. The effects of the nature of electroactive solute molecules on Dapp, ks, and the half-wave potentials(E1/2) are discussed.

Physical Diffusion and Electron-transfer Dynamics of Electroactive Solutes in Polymer Electrolytes Ⅱ. Effect of the Ionic Size of Supporting Electrolytes

The ditheion coefficients(Dapp) and the heterogeneous electron-transfer rate constan(ks)for ferrocene in MPEG/salt electrolytes were determined by using Steady-stae voltammetry. The temperature dependence of the two parameters obeys the Arrhenius equstion. The effect of the ionic size of sir supporting electrolytes on diffusion and electron transfer dynamics of fermcene was discussed

Wireless Power Generation Strategy Using EAP Actuated Energy Harvester for Marine Information Acquisition

The energy of a radio wave is reduced through the dispersion, the refraction and the absorption because the medium transferring the vibration of a radio wave is the seawater. In the end the reduced energy of a radio wave causes the reduced transmitting length for communication, the long postponed communication and the frequent error. The subsea communication for the marine environment monitoring which must overcome the weak points of the RF wave and the most practical method for the marine sensor network realization is to use the acoustic wave method, but the energy consumption rate of the acoustic wave communication method is about 100 times greater than the one of the RF wave method. So, the power supply of the sensor node in the marine sensor network system is the most important interest field. In this study, the sample which consists of an acrylic elastomer(VHB4905 film from 3M), conductible carbon grease(from MG chemical) and electric wire for the basic study of an energy harvesting strategy and technique using EAP actuator was fabricated, and the conductible carbon grease was used for an electrode. The characteristics of the fabricated sample were analyzed through the experiment. We also mixed carbon grease with aluminum powder for conductibility improvement, and the effect of the mixed electrode was confirmed through the conductivity measurement.

Multifunctional electroactive bio-adhesive for robustly-integrated wound therapy and postoperative wound-status warning and assessment

Wound abnormalities such as secondary wound laceration and inflammation are common postoperative health hazards during clinical procedures.The continuous treatment,healing induction,and real-time visualization of wound status and complications,including wound re-tearing,inflammation,and morphology,are key focal points for comprehensive healthcare.Herein,an on-demand quadruple energy dissipative strategy was proposed for the nanoengineering of a physically and chemically synergistic double-layer gelatin-based bio-adhesive(DLGel)by combining a multi-network adhesive layer and a versatile electroactive energy dissipative layer based on contrivable interlocking micro-pillar arrays and crosslinked polymer chains.The subtly multiple energy dissipation designs enable DLGel with robust adhesive strength to omnipotently wet and dynamic tissue,providing a basis for reliable wound closure.DLGel achieves comprehensive wound-healing induction through electrical stimulation and possesses reversible underwater light/thermal adhesion,excellent hemostatic performance,outstanding antimicrobial properties,and self-repair capability.Furthermore,a novel deep-learning strategy is creatively established to respond to mechanical deformation due to wound anomalies.This strategy translates biological information into visual graphics,providing real-time early warning and assessment of postoperative wound-abnormality/-morphology,such as laceration,inflammation,and necrosis.Therefore,DLGel and its associated signal collection and processing protocol enable the integration of reliable wound closure,wound healing,and real-time postoperative wound-status warning and assessment within the unobservable and undetectable“black box”regions in a context of non-clinical comprehensive therapy.

Dynamic membrane filtration accelerates electroactive biofilms in bioelectrochemical systems

Bioelectrochemical systems(BES)have emerged as a dual-function technology for treating wastewater and recovering energy.A vital element of BES is the rapid formation and maintenance of electroactive biofilms(EABs).Previous attempts to accelerate EAB formation and improve electroactivities focused on enhancing the bacterial adhesion process while neglecting the rate-limiting step of the bacterial transport process.Here,we introduce membrane filtration into BES,establishing a dynamic membrane filtration system that enhances overall performance.We observed that optimal membrane flux considerably reduced the startup time for EAB formation.Specifically,EABs established under a 25 L m^(-2)h^(-1)flux(EAB_(25)LMH)had a formation time of 43.8±1.3 h,notably faster than the 51.4±1.6 h in the static state(EAB_(0)LMH).Additionally,EAB_(25)LMH exhibited a significant increase in maximum current density,approximately 2.2 times higher than EAB_(0)LMH.Pearson correlation analysis indicated a positive relationship between current densities and biomass quantities and an inverse correlation with startup time.Microbial analysis revealed two critical findings:(i)variations in maximum current densities across different filtration conditions were associated with redox-active substances and biomass accumulation,and(ii)the incorporation of a filtration process in EAB formation enhanced the proportion of viable cells and encouraged a more diverse range of electroactive bacteria.Moreover,the novel electroactive membrane demonstrated sustained current production and effective solid-liquid separation during prolonged operation,indicating its potential as a viable alternative in membrane-based systems.This approach not only provides a new operational model for BES but also holds promise for expanding its application in future wastewater treatment solutions.

Role of the cathode chamber in microbial electrosynthesis:A comprehensive review of key factors

The consumption of non-renewable fossil fuels has directly contributed to a dramatic rise in global carbon dioxide(CO_(2))emissions,posing an ongoing threat to the ecological security of the Earth.Microbial electrosynthesis(MES)is an innovative energy regeneration strategy that offers a gentle and efficient approach to converting CO_(2) into high-value products.The cathode chamber is a vital component of an MES system and its internal factors play crucial roles in improving the performance of the MES system.Therefore,this review aimed to provide a detailed analysis of the key factors related to the cathode chamber in the MES system.The topics covered include inward extracellular electron transfer pathways,cathode materials,applied cathode potentials,catholyte pH,and reactor configuration.In addition,this review analyzes and discusses the challenges and promising avenues for improving the conversion of CO_(2) into high-value products via MES.

Interactions among microorganisms functionally active for electron transfer and pollutant degradation in natural environments

Compared to single microbial strains,complex interactions between microbial consortia composed of various microorganisms have been shown to be effective in expanding ecological functions and accomplishing biological processes.Electroactive microorganisms(EMs)and degradable microorganisms(DMs)play vital roles in bioenergy production and the degradation of organic pollutants hazardous to human health.These microorganisms can strongly interact with other microorganisms and promote metabolic cooperation,thus facilitating electricity production and pollutant degradation.In this review,we describe several specific types of EMs and DMs based on their ability to adapt to different environments,and summarize the mechanism of EMs in extracellular electron transfer.The effects of interactions between EMs and DMs are evaluated in terms of electricity production and degradation efficiency.The principle of the enhancement in microbial consortia is also introduced,such as improved biomass,changed degradation pathways,and biocatalytic potentials,which are directly or indirectly conducive to human health.