Electrode Impedance Research Articles

Enhancing the Pseudocapacitive Energy Storage of Coordination Polymers by Artificially Constructed Defective Sites Anchoring Redox-Active Species.

Coordination polymers (CPs) have emerged as potential energy storage materials for supercapacitors due to their tunable chemical composition, structural diversity, and multielectron redox-active sites. However, besides poor cycling stability, the practical application of dense CPs in supercapacitors is generally limited by low specific capacitance and high resistance, which are caused by their low specific surface area and dense frameworks, resulting in insufficient redox reactions of metal sites and poor ion diffusion, respectively. Here, we synthesize a new dense CP {CP-1: [Ce(obb)(HCOO)]∞} via self-assembly of the Ce cation and 4,4'-oxidibenzoate (obb2-). The specific capacitance of CP-1 increases by 156.7 times, and its lifetime after charge-discharge for 5000 cycles is elevated from 62 to 86.7%; meanwhile, the resistance of the positive electrode is reduced from 1.05 to 0.73 Ω through this defect engineering strategy (DES), i.e., cyclic voltammetry sweep in a sulfuric acid electrolyte to artificially construct defects for anchoring the redox-active species (ferricyanide anions). To investigate the universality of this strategy, we have applied it to the other two previously reported CPs {CP-2: [Ce4(obb)6(H2O)9·(H2O)]∞ and CP-3: [Ce2(obb)3(OH)(H2O)(DMF)]∞}, which are also obtained by self-assembly of the Ce cation and obb2- ligand. By comparing the electrochemical performances of the three pristine CPs and their corresponding defect-engineered CPs obtained through the DES, we have found that (i) this strategy is effective in enhancing the electrochemical performances for all three CP materials and (ii) the effect of this strategy on improving the electrochemical performance of CP-1 with a three-dimensional dense network is better than that of CP-3 with a layered structure, and both are better than that of CP-2 with small pores. This work demonstrates a new effective universal strategy for boosting the electrochemical performances of CPs, thus advancing their application in the energy storage field.

Investigation into the impedance, dielectric behavior, and conductivity within p-silicon/n-nanocrystalline iron disilicide heterojunctions and equivalent circuit model in relation to temperature

The p-Si/n-nanocrystalline FeSi2 heterojunctions constructed through facing-targets sputtering were characterized for impedance under various frequencies and temperatures of between 160−400 K. Imaginary and real impedance plots for all temperatures demonstrated single semicircular arc with negative temperature dependency. From the arc, a circuit model equivalent to electrode resistance serially connected to several loops, each consisting of a parallel circuit comprising a resistance//constant phase element (Q), corresponding to the crystallite, crystallite boundary, and interface. All resistances increased with decreasing temperatures, while the Q values decreased but behaved as ideal capacitors for all temperatures. The dielectric constants versus increasing temperature demonstrated a linear increase. At 300 K and 1 MHz, the dielectric constant was 24.5 with 0.1 loss tangent, denoting its possible usage for filtration and storage. The alternating-current conductivities disclosed that direct-current conductivities increased as the temperature increased. The exponents from Jonscher's fit were 1 or less around 180 K and the values beyond 1 at higher temperatures, indicating the shift from long transitional transport to localized hopping transport. The activation energy based on conductivities was higher than the one based on relaxation times, implying that excess charge led to more energy requirements for transportation.

Impact of Na-Carboxymethyl Cellulose Binder Type on Hard Carbon Performance and SEI Formation in Sodium-Ion Batteries.

The development of hard carbon (HC) electrodes using biobased binders, formulated in water solvent, is of great interest for Na-ion batteries. Five Na-carboxymethyl cellulose (CMC) binders with different molecular weights and degrees of substitution were investigated. The increase in the CMC molecular weight led to an increase in the volume of water necessary for slurry preparation and a decrease in the electrode mass loading. Moreover, the adhesion of the slurry was strongly impacted by the aluminum current collector properties. A high initial Coulombic efficiency, iCE (up to ∼90%), and reversible capacity (up to 334 mAh g-1 at C/10) were obtained in Na half-cells. Post-mortem XPS analyses performed on several electrodes under various conditions allowed a better understanding of the formation and composition of the solid electrolyte interphase (SEI) layer. The genesis of SEI was initially chemically driven: to a small extent, by HC and to a greater extent, by the Na metal. However, SEI formation was mainly governed by the electrochemical-driven degradation of the electrolyte salt and solvent. The SEI layer composed of an inorganic-rich core and an organic-rich shell significantly decreased the resistance of the HC electrode, allowing superior iCE while maintaining high capacity retention (96.2%), after 100 cycles at 1C.

Fast Numerical Optimization of Electrode Geometry in a Two-Electrode Electric Resistance Furnace Using a Surrogate Criterion Derived Exclusively from an Electromagnetic Submodel

The Joule heat generated by current flow between electrodes in a resistance furnace not only melts and heats the charge but also induces mixing of the molten material. Increased mixing promotes improved chemical and temperature uniformity within the bath. This paper presents a novel approach to effectively optimizing electrode geometry in resistance furnaces. The method relies on a surrogate criterion derived exclusively from an electromagnetic submodel, which governs the process hydrodynamics. This criterion is based on the location of the Joule heat generation center in the bath. Its idea is to lower this center as much as possible while keeping it close to the vertical bath axis. Owing to this, the best conditions for the development of natural convection were obtained. The developed methodology was demonstrated through an application to a two-electrode furnace. The results showed that the influence of forced MHD convection is negligible in this furnace (with a Lorentz force of only about 0.0015 N/kg). The validation of the optimized geometry, derived using solely the electromagnetic submodel, was carried out using a full process model, including time-consuming hydrodynamic calculations. The proposed optimization methodology enabled a 10-fold increase in the average mixing velocity (from 0.0008 to 0.0084 m/s). The main significance of the presented study is the introduction of a surrogate criterion that allows for a multiple reduction in the time of numerical optimization of the mixing intensity in electrode resistance furnaces in comparison to the standard solution based on the flow velocity criterion determined from the hydrodynamic model.

Single-Electrode Flow Cell for Electrochemiluminescent Flow Analysis.

Flow injection analysis and liquid chromatography are frequently combined with electrochemiluminescence (ECL) for flow analysis. Almost all electrochemistry flow analyses employ traditional three-electrode electrochemical flow cells which have working electrode, counter electrode, and reference electrode; however, it is expensive and difficult to fabricate a traditional three-electrode electrochemical flow cell and inconvenient to renew the electrode. In this study, we have developed a single-electrode flow cell using commercially available conductive polyethylene film as the only electrode through potential differences induced by the electrode resistance for the first time. The single-electrode flow cell features a simple structure, easy renewal of the electrode, and low cost compared to the traditional three-electrode electrochemical flow cells. Taking the typical Ru(bpy)32+/oxalate ECL system as the analytical model, flow analysis of clinically important oxalate was achieved using single-electrode flow cell. A regression linear equation was obtained over the oxalate concentration ranges from 1 to 200 μM, with a detection limit of 0.92 μM. The single-electrode flow cell is promising for ECL flow analysis.

High-Performance SAW-Based Microfluidic Actuators Composed of Sputtered Al–Cu IDT Electrodes

To realize highly sensitive SAW devices, novel Al–Cu thin films were developed using a combinatorial sputtering system. The Al–Cu sample library exhibited a wide range of chemical compositions and electrical resistivities, providing valuable insights for selecting optimal materials for SAW devices. Considering the significant influence of electrode resistivity and density on acoustic wave propagation, an Al–Cu film with 65 at% Al was selected as the IDT electrode material. The selected Al–Cu film demonstrated a resistivity of 6.0 × 10−5 Ω-cm and a density of 4.4 g/cm3, making it suitable for SAW-based microfluidic actuator applications. XRD analysis revealed that the Al–Cu film consisted of a physical mixture of Al and Cu without the formation of Al–Cu alloy phases. The film exhibited a fine-grained microstructure with an average crystallite size of 7.5 nm and surface roughness of approximately 6 nm. The SAW device fabricated with Al–Cu IDT electrodes exhibited excellent acoustic performance, resonating at 143 MHz without frequency shift and achieving an insertion loss of −13.68 dB and a FWHM of 0.41 dB. In contrast, the Au electrode-based SAW device showed significantly degraded acoustic characteristics. Moreover, the SAW-based microfluidic module equipped with optimized Al–Cu IDT electrodes successfully separated 5 μm polystyrene (PS) particles even at high flow rates, outperforming devices with Au IDT electrodes. This enhanced performance can be attributed to the improved resonance characteristics of the SAW device, which resulted in a stronger acoustic radiation force exerted on the PS particles.

PEDOT:PSS Electropolymerization Protocol for Microelectrodes Enabling Low‐Cost Impedance‐Based Cellular Assays

ABSTRACTElectric cell‐substrate impedance sensing (ECIS) is a label‐free method for in vitro cell analysis in different research fields such as virology, cancer research, and stem cell research. In the ECIS configuration, the working electrode (WE) is typically much smaller than the counter electrode, thus the measured impedance between both is mainly dominated by the impedance of the WE. However, if the impedance of the WE is too high, it is challenging to detect small changes in impedance caused by cells attached to the electrode surface. In this study, we present an easily reproducible and cost‐effective method to lower the impedance of commercial ECIS electrodes, and by this increase the cell contribution in adhesion assays. Hereby we deposit a thin layer of poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) only onto the gold electrodes by electropolymerization and study the layer characteristics in detail. We compare cell‐free and cell‐covered impedance spectra of gold and PEDOT:PSS electrodes recorded with a low‐cost potentiostat and analyze the ECIS spectra of two different cell lines in detail.

Poly(o-anisidine) and poly(o-anisidine-co-aniline) polymers synthesized on the ZnFeNi alloy coated steel surface

Abstract ZnFeNi alloy was synthesized on the carbon steel surface in a sulfate bath using the galvanostatic method at a constant current of 1.5 mA for 300 seconds. Poly(o-anisidine) homopolymer and poly(o-anisidine-co-aniline) copolymer were synthesized on the ZnFeNi coated electrode surface. Poly(o-anisidine) homopolymer was synthesized in 0.05 M o-anisidine+0.2 M sodium oxalate medium, and poly(o-anisidine-co-aniline) copolymer was synthesized in 0.05 M o-anisidine+0.05 M aniline+0.2 M sodium oxalate medium. Electrochemical synthesis was carried out by cyclic voltammetry technique. The synthesized materials were characterized by electrochemical impedance spectroscopy, linear sweep voltammetry, open circuit potential-time and anodic polarization curves. Open circuit potential-time curves showed that polymer coatings had higher open circuit potential. By linear sweep voltammetry measurements, it was determined that ZnFeNi alloys were present at the base of the polymer layers after polymer synthesis. It was understood from the anodic polarization curves that the polymer coated electrodes had lower current values ​​than the uncoated ZnFeNi coated electrode, and the poly(o-anisidine) coated electrode had lower current values ​​than the poly(o-anisidine-co-aniline) coated electrode. From electrochemical impedance spectroscopy measurements, it was determined that the polarization resistance of polymer-coated electrodes was higher than the polymer-free electrode during long periods of waiting in 3.5% corrosive solution. Among the polymer-coated electrodes, it was understood that the homopolymer poly(o-anisidine) showed better corrosion performance than the poly(o-anisidine-co-aniline) copolymer.

A control-oriented comprehensive model of PEM electrolyzer considering double-layer capacitance

The modeling of electrochemical and thermal characteristics of proton exchange membrane (PEM) electrolyzer is significant in the hydrogen production process. However, the calculation of electrode impedance and double-layer capacitance during operation is not accurate enough currently, and the electrothermal coupling characteristics of hydrogen production devices are not fully considered. In this paper, the multi-stage equivalent circuit of the PEM electrolyzer is designed using electrochemical impedance spectroscopy (EIS) and the time-constant fitting method. In addition, according to the temperature control system of the actual hydrogen production device, the electro-thermal model of the PEM electrolyzer is established, in which the fuzzy PID control is used to maintain the temperature stability. Moreover, the electrical characteristics and temperature characteristics are simulated in different time scales. Finally, compared to the existing models, the proposed model is more accurate, and it indicates that the proposed model has better accuracy against the existing models.

Improved MnO2 based electrode performance arising from step by step heat treatment during electrodeposition of MnO2 for determination of paracetamol, 4-aminophenol, and 4-nitrophenol

The design of electrochemical sensors is crucial considering important factors such as efficiency, low cost, biocompatibility, and availability. Manganese oxides are readily available, low-cost, and biocompatible materials, but their low conductivity limits their efficiency as sensors. Today, morphology engineering of manganese oxide has been one of the most common research topics, because manganese oxides’ electrochemical properties are highly dependent on their morphologies. In this study, a method for reducing the charge transfer resistance (Rct) of MnO2-based electrodes was established by the cyclic voltammetry technique accompanied by step-by-step heat treatment to electrodeposition MnO2 nanofilm, which remarkably improved the Rct. Next, the sensing performance of MnO2/FTO for two separate measurements was examined, one for the simultaneous measurement of paracetamol (PAR) and 4-aminophenol (4-APh), and the other for the measurement of 4-nitrophenol (4-NP). Under the optimum conditions, the linear ranges of 4-APh, PAR, and 4-NP, were 0.8 to 22.0 µM, 2.0 to 55.0 µM, and 0.1–250 µM, with limits of detection (LOD) of 0.19 µM, 0.60 µM, and 0.01 µM, respectively. It also was unaffected by a 200-fold excess of interferences. In addition, the designed sensor was successfully applied to the analysis of real samples.

Characterization of Oxygen Diffusion and Catalytic Behavior of Composite Materials in Solid Oxide Fuel Cells Using the Non-destructive Adler-Lane-Steele Method

Solid oxide fuel cells (SOFCs) are technologically interesting because they provide high-efficiency energy conversion via an electrochemical reaction within the cells. To bring SOFC to market, researchers must develop highly electroactive, low-cost devices that are chemically stable in both high (800 – 1000 °C) and low (600 – 800 °C) temperatures, as well as optimize oxygen reduction in electrodes. The electrochemical performance of SOFC is highly dependent on the catalytic activity (or catalyst behaviours) of the electrode materials involved in the oxygen reduction reaction due to the slower oxygen reduction kinetics at lower temperatures. Understanding the fundamental properties of oxygen self-diffusion in solid-state ionic systems is critical for developing nextgeneration electrolyte and electrode material compositions and microstructures that enable SOFCs to operate at lower temperatures more effectively, durably, and affordably. To date, the most common method for evaluating electrocatalytic performance is electrochemical impedance spectroscopy (EIS), which causes sample damage due to its set-up procedure. As a result, modelling approaches have been used to better understand the reaction mechanism, oxygen diffusion coefficient, and kinetics of SOFC electrode reactions, including the mixed ionic electronic conductor (MIEC)-based electrode. Several models have recently been developed to represent the reaction mechanisms of SOFCs, with Adler-Lane-Steele (ASL) mathematical theory believed to be suitable for predicting oxygen gas diffusion through the pores of the MIEC-based materials. Hence, the aim of this paper is to validate the area-specific resistance of composite electrodes using the ASL modeling technique rather than the standard EIS analysis. The findings are significant in contributing to the development of a new non-destructive method for analyzing the catalytic behavior of SOFC components.

Optimization of the performance of copper/graphite system for GIL Tri‐post grounding electrode based on plasma sintering technology

Grounding electrodes, as crucial components of GIL bushings, experience friction with the GIL shell during long-term operation, generating metal particles that induce partial discharge. This phenomenon can lead to internal insulation breakdown, severely compromising GIL operation. This study focuses on enhancing the wear resistance of grounding electrodes by proposing a solution involving copper-graphite composites. Copper/graphite composite materials were fabricated using Spark Plasma Sintering technology. Additionally, the impact of graphite content and particle size on wear resistance, hardness, and electrical conductivity was comprehensively analyzed. Performance evaluation using radar chart analysis identified the optimal solution. The results indicate that at a sintering temperature of 960 °C, pressure of 45 MPa, and holding time of 15 min, with a graphite mass fraction of 7 %, the grounding electrode material exhibits a smooth surface and uniform distribution of graphite. Furthermore, when the graphite particle size is 4 μm, the friction coefficient remains approximately 0.7 with minimal fluctuations. The abrasion produces scratches measuring only 190 μm, and the wear rate is recorded at 2.1128 × 10−4 mm³/N·m, while the hardness reaches 59.6 HV, an increase of 19.6 HV compared to a particle size of 40 μm. In conclusion, an appropriate graphite content effectively enhances the wear resistance of the grounding electrode, and a reduction in graphite particle size optimizes overall performance. When the composite material contains 7 % graphite with a particle size of 4 μm, the performance is optimal, allowing the grounding electrode to maintain its original properties while demonstrating excellent wear resistance. This study provides a significant approach to optimizing the performance of grounding electrodes.

Enhanced Oxygen Evolution Reaction Performance of NiMoO4/Carbon Paper Electrocatalysts in Anion Exchange Membrane Water Electrolysis by Atmospheric-Pressure Plasma Jet Treatment.

NiMoO4 was grown on carbon paper (CP) by a hydrothermal method. A rapid and high-temperature atmospheric-pressure plasma jet (APPJ) process was used to generate more oxygen-deficient NiMoO4 on the CP surface to serve as an electrode material for the oxygen evolution reaction (OER). After 60 s of APPJ treatment, the overpotential of the electrode at 100 mA/cm2 decreased to 790 mV and that at 10 mA/cm2 decreased to 368 mV. Additionally, the charge transfer resistance decreased from 2.8 to 1.2 Ω, indicating that APPJ treatment effectively reduced the electrode overpotential and impedance. The effect of NiMoO4/CP/APPJ-60 s on the anion exchange membrane water electrolysis (AEMWE) system was also tested. At a system temperature of 70 °C and current density of 100 mA/cm2, the energy efficiency reached 95.1%, and the specific energy consumption decreased from 4.02 to 3.83 kWh/m3. These results demonstrate that the APPJ-treated NiMoO4/CP electrode can effectively enhance the OER performance in water electrolysis and improve the energy efficiency of the AEMWE system. This approach shows promise in replacing precious metal electrodes, thereby potentially reducing the cost and providing an environmentally friendly alternative.

Investigation of an improved ceramic-based pulse-forming line based on impedance matching electrode.

A ceramic-based pulse-forming line (PFL) is a solid-state device with a wide range of applications in compact pulsed power systems. In this paper, the characteristic impedance of a ceramic-based PFL is theoretically analyzed, and an improved PFL based on an impedance matching electrode is proposed. The improved PFL effectively increases the flat-top ratio and reduces the rise and fall times, enhancing its potential applicability. Experiments using the improved PFL show that, under a charging voltage of 33kV and with an impedance matching load, the output pulse width can reach 86ns with a matching impedance of 3.9Ω. The improved PFL output waveform has a flat-top ratio that reaches 72%, compared with 49.5% in a typical PFL, and exhibits shorter rise and fall times.

Evaluation of simplified wireless EEG recordings in the neurological emergency room.

In the neurological emergency room (nER), timely electroencephalography (EEG) diagnostic is often crucial in patients with altered state of consciousness as well as in patients presenting with a first seizure. Yet, routine-EEG (rEEG) is often not available, especially during off-hours. We analyzed the value of a commercially available, simplified wireless eight-channel EEG recording (swEEG, CerebAir® EEG headset, Nihon Kohden), applied by non-EEG-specialized medical students, in patients presenting in our nER with (suspicion of) epileptic seizures and/or loss of or altered state of consciousness between 08/2019 and 08/2022. We evaluated the feasibility and validity compared to a standard rEEG (21 electrodes according to the international 10/20 system) and also included the clinical follow-up of the patients. 100 patients were included in our analysis (mean age 57.6 ± 20.4 years; 61 male). Median time of electrode application was 7 minutes (range 4-20 minutes), with significantly longer duration in patients with altered level of consciousness (median 8 minutes, p = 0.035). Electrode impedances also differed according to state of consciousness (p = 0.032), and were higher in females (p<0.001). 55 patients received additional rEEG, either during their acute nER stay (25) and/or during the next days (38). Considering normal EEG findings vs. pathological slowing vs. epileptiform activity, swEEG matched first rEEG results in 48/55 cases (87.3%). Overall, swEEG detected the same or additional pathological EEG patterns in 52/55 cases (94.5%). In 7/75 patients (9.3%) who did not receive rEEG, or had their rEEG scheduled to a later time point during their hospital stay, swEEG revealed important additional pathological findings (e.g. status epilepticus, interictal epileptiform discharges), which would have triggered acute therapeutic consequences or led to further diagnostics and investigations. The introduced swEEG represents a practicable, valuable technique to be quickly applied by non-EEG-specialized ER staff to initiate timely diagnostic and guide further investigations and treatment in the nER. Moreover, it may help to avoid under-diagnostic with potentially harmful consequences caused by skipped or postponed regular 10/20 EEG examinations, and ultimately improve the outcome of patients.

A comparison of electromyography techniques: surface versus intramuscular recording.

This review is a comprehensive guide for electromyography (EMG) researchers, providing a comparison of skin EMG recording (surface EMG: sEMG and high-density sEMG: HD-sEMG) and intramuscular EMG recording (multi-motor unit-MMU and single motor unit electromyography-SMU). We delve into the nuances of techniques, highlighting their strengths and limitations in quantifying muscle activation during dynamic and static conditions. We first examine how EMG signals change with time, focussing on the interplay between motor unit synchronisation and signal amplitude. The review then explores the impact of electrode placement on signal quality. We further discuss the challenges of signal cancellation, crosstalk from neighbouring muscles, and motion artifacts, which can significantly affect signal integrity. Finally, we address the temporal changes in electrode impedance and its implications for data interpretation. Our analysis proposes that specific research objectives should guide the choice amongst sEMG, HD-sEMG, SMU and MMU. MMU, which records the peak counts of individual motor unit action potentials from a localised muscle area, is particularly suited for studying deep or small muscles during static and dynamic activities. Its high sensitivity to motor unit recruitment and discharge rates minimises the impact of factors such as signal cancellation and motion artefacts. Conversely, sEMG is well-suited for short-duration, isometric assessments of large, superficial muscles. HD-sEMG helps study single motor unit properties under isometric conditions. SMU is particularly suited for studying neuronal networks between stimulated sites and motor neurons. This review aims toprovideresearchers with the information to select the most appropriate EMG technique for their investigations.

Challenges and Prospects of Low-Temperature Rechargeable Batteries: Electrolytes, Interfaces, and Electrodes.

Rechargeable batteries have been indispensable for various portable devices, electric vehicles, and energy storage stations. The operation of rechargeable batteries at low temperatures has been challenging due to increasing electrolyte viscosity and rising electrode resistance, which lead to sluggish ion transfer and large voltage hysteresis. Advanced electrolyte design and feasible electrode engineering to achieve desirable performance at low temperatures are crucial for the practical application of rechargeable batteries. Herein, the failure mechanism of the batteries at low temperature is discussed in detail from atomic perspectives, and deep insights on the solvent-solvent, solvent-ion, and ion-ion interactions in the electrolytes at low temperatures are provided. The evolution of electrode interfaces is discussed in detail. The electrochemical reactions of the electrodes at low temperatures are elucidated, and the approaches to accelerate the internal ion diffusion kinetics of the electrodes are highlighted. This review aims to deepen the understanding of the working mechanism of low-temperature batteries at the atomic scale to shed light on the future development of low-temperature rechargeable batteries.

An active and Cr-tolerant high-entropy La0.7Sr0.3FeO3-δ based cathode for solid oxide fuel cells

The development of high active and stable cathode materials is one of the main challenges of intermediate temperature solid oxide fuel cells (SOFCs). Herein, a high-entropy Fe-based perovskite oxide La0.7Sr0.3Fe0.3Ni0.3Co0.3Mo0.1O3-δ (LSFNCM) is synthesized by self-propagation combustion based on La0.7Sr0.3FeO3-δ (LSF) and the electrochemical properties are systematically tested. The symmetric half-cell with the LSFNCM cathode has a high catalytic activity with a polarization impedance of 0.12 Ω cm2 at 800 °C, and also shows outstanding CO2 resistance and chromium resistance owing to the entropy stabilization strategy. After 50h of treatment in a 10% CO2 environment, the polarization impedance of the LSF electrode increases by 8.89 Ω cm2, while that of the LSFNCM electrode only increases by 1.81 Ω cm2. Additionally, after being treated for 24h in a chromium vapor environment, the polarization impedance of the LSF electrode increases by 5.95 Ω cm2, whereas that of the LSFNCM electrode only increases by 0.44 Ω cm2. Moreover, the single cell with LSFNCM cathode exhibits the maximum power density of 932.82 mW/cm2 and the polarization impedance of 0.34 Ω cm2 at 800 °C with humidify hydrogen as fuel. Our results indicate that high-entropy perovskite oxide LSFNCM is an active and Cr-tolerant promising cathode for SOFCs.

Enhanced Photovoltaic Performance of Poly(3,4-Ethylenedioxythiophene)Poly(N-Alkylcarbazole) Copolymer-Based Counter Electrode in Dye-Sensitized Solar Cells

Conducting polymers are emerging as promising alternatives to rare and expensive platinum for counter electrodes in dye-sensitized solar cells; due to their ease of synthesis, they can be chemically tuned and are suitable for roll-to-roll production. Among these, poly (3,4-ethylenedioxythiophene) (PEDOT)-based counter electrodes have shown leading photovoltaic performance. However, certain conductivity issues remain that affect the effectiveness of these counter electrodes. In this study, we present an electropolymerized PEDOT and poly(N-alkylated-carbazole) copolymer as an efficient electrocatalyst for the reduction in I3− in dye-sensitized solar cells. Copolymerization with N-alkylated carbazoles significantly increases the conductivity of the polymer film and facilitates rapid charge transport at the interface between the polymer electrode and the electrolyte. The length of the alkyl substituents also plays a crucial role in this improvement. Electrochemical analysis showed a reduction in charge transport resistance from 3.31 Ω·cm2 for PEDOT to 2.26 Ω·cm2 for the PEDOT:poly(N-octylcarbazole) copolymer, which is almost half the resistance of a platinum-based counter electrode (4.12 Ω·cm2). Photovoltaic measurements showed that the solar cell with the PEDOT:poly(N-octylcarbazole) counter electrode achieved an efficiency of 8.88%, outperforming both PEDOT (7.90%) and platinum-based devices (7.57%).

Nanosilica-Reinforced Poly(dimethylsiloxane) Stretchable Transparent Electrodes and Multifunctional Applications.

Soft and stretchable transparent electrodes still face many challenges, requiring a balance between stretchability, conductivity, transparency, and stability. In this paper, poly(dimethylsiloxane) (PDMS) elastomer is selected, and amphoteric nonionic surfactants (Triton X-100) are introduced to improve the interfacial bonding between nanosilica (SiO2) and the elastic matrix. At the same time, a fluorosilane-modified glass template is used to induce nanosilica enrichment on the membrane surface. Based on the dual effects of nanoenhancement and surface regulation, a PDMS transparent nanocomposite membrane with good stretchability, surface hydrophilicity, and easy in situ polymerization of polydopamine can be obtained. Silver nanowires (AgNWs) and poly(3,4-ethylenedioxythiophene)/polystyrenesulfonate (PEDOT:PSS) conductive polymers can be assembled layer by layer on the surface of the nanocomposite membrane by simple spin coating and heat treatment. The transmittance of the soft and stretchable composite membrane can reach 63% in the visible light range, and the strength and elongation at break increase to 2.30 MPa and 150%, respectively. The sheet resistance of the stretchable transparent dry electrode is as low as about 6 Ω/sq. After being placed in the air for 3 months, the resistance increment is less than 5%, showing good environmental stability. The stretchable transparent electrode prepared based on the material-structure-preparation integrated method has brilliant application potential in wearable thermal management, electrochromism, strain sensing, and electromagnetic shielding.