Counter Electrode Research Articles

Remove hydrogen and store it too: an acid-in-clay based electro-chemical solution.

Extracting hydrogen from metallic components can open up a new pathway for preventing hydrogen embrittlement. To this end, we propose an electrochemically driven, all-solid method for hydrogen control, capable of both extracting and storing hydrogen simultaneously. In this approach, we employ acid-in-clay as a proton conducting electrolyte at room temperature. Through this electrochemical treatment, hydrogen is efficiently extracted from pre-charged steels, thereby restoring their tensile properties and preventing embrittlement. Moreover, it has been confirmed that the extracted hydrogen can be efficiently collected at the counter electrode, demonstrating the significant advantages of the process.

In–Li Counter Electrodes in Solid‐State Batteries – A Comparative Approach on Kinetics, Microstructure, and Chemomechanics

AbstractA key challenge for solid‐state batteries is the fabrication of high‐capacity cathodes with high area loading and good rate performance. To reliably quantify the performance of high‐capacity cathodes, electrochemically stable, and high‐rate counter electrodes are essential. Otherwise, a three‐electrode setup is required. In–Li alloy electrodes are used for years in a kind of standard approach, since these seem to offer stable operation. In this comparative study, seven preparation methods for In–Li electrodes are examined, determining their suitability for cathode testing. The microstructure of a planar (i.e., foil) and a particle‐based (i.e., composite) anode configuration is analyzed in more detail. Their rate‐dependent electrode performance as well as electrochemical and chemomechanical reversibility in full‐cell configuration are analyzed. The combined results demonstrate the limitations of In–Li electrodes for high‐capacity testing, especially at high rates, while confirming their suitability for simple lab‐scale testing. Preparation significantly influences the electrode microstructure and kinetics, consequently impacting the performance benchmarks of cathodes. These findings underscore both the challenges involved in applying In–Li counter electrodes and the resulting limited comparability of results from different laboratories.

Dye-Sensitized Solar Cells: Unveiling Barriers to Enhanced Performance

Global energy consumption is steadily increasing, and the world's reliance on non-renewable energy sources such as hydroelectric and thermoelectric power is unsustainable due to their diminishing availability. The photovoltaic (PV) devices have been developed through various methods for various applications, and among these, Dye- Sensitized Solar Cells (DSSCs) have emerged as a cost-effective and easily implementable technology. This comprehensive review paper offers an in-depth overview of DSSCs, aiming to provide insights into their construction, working principles, applications, and the significant challenges they face, primarily related to their low efficiency and stability. To fully commercialize DSSCs and compete with existing energy technologies, it is imperative to continue addressing and overcoming the efficiency challenges outlined in this review. KEYWORDS: TiO2, Dye Sensitized Solar Cell, Electrolyte, Photoanode, Counter Electrode

Multi-sensing yarns for continuous wireless sweat lactate monitoring

Textile integrated sensors based on conductive, electrochemically active microfibers can enable inexpensive, nearly invisible distributed sensing of sweat in clothing. Reduced graphene oxide fibers are mechanically robust, conductive, and can be easily functionalized to form a variety of sensors with properties comparable to planar fabricated sensors, given their ability to work both as electrical interconnections and as a base electrode. Here, we present an electrochemical yarn based on modified dry-spun reduced graphene oxide fibers. This braided format contains reference, counter electrode, a lactate-responsive fiber functionalized with lactate oxidase, and a pH-sensing fiber for calibration in a single, robust, weavable format. This electrochemical yarn was integrated into a demonstrator wearable textile-patch capable of continuous data collection and wireless data transmitted to an ad-hoc app. The yarns perform comparably to traditional probes in a format of broad utility for standalone or integrated monitoring of physiological parameters.

Enhanced performance of Mg and La co-doped TiO2(98%)−ZrO2(2%) photoanode for dye-sensitized solar cells

Abstract This study explores the effects of magnesium (Mg) and lanthanum (La) doping on the performance of dye-sensitized solar cells (DSSCs) utilizing TiO2(98%)−ZrO2(2%) (TZ, TZM, and TZL) photoanodes. The photoanodes were fabricated using a spin-coating sol–gel method, followed by calcination at 400°C. The structural, morphological, crystallographic, and optical properties of the proposed photoanode composites were characterized by X-ray diffraction, transmission electron microscopy, and ultraviolet–visible spectroscopy. The crystallite sizes of the synthesized thin films varied from 21.16 to 59.04 nm for the TZ, TZM, and TZL compositions. The current–voltage measurements of DSSCs based on TZL8 photoanode, cobalt sulfide-doped graphene counter electrode, and N719 dye revealed the highest efficiency of nearly 5.052%. The assembled DSSCs exhibited an open-circuit voltage of 0.74 V, a short-circuit current density of 9.964 mA/cm2, and a fill factor of 0.685. The enhancement in open-circuit voltage and short-circuit current density could be attributed to the improved electronic and microstructures of the proposed photoanodes.

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.

Progress in MXenes and Their Composites as Electrode Materials for Electrochemical Sensing and Dye-Sensitized Solar Cells

In the present mini-review article, we have compiled the previously reported literature on the fabrication of MXenes and their hybrid composite materials based electrochemical sensors for the determination of phenolic compounds and counter electrodes for platinum (Pt)-free dye-sensitized solar cells (DSSCs). MXenes are two-dimensional (2D) materials with excellent optoelectronic and physicochemical properties. MXenes and their composite materials have been extensively used in the construction of electrochemical sensors and solar cell applications. In this paper, we have reviewed and compiled the progress in the construction of phenolic sensors based on MXenes and their composite materials. In addition, co1.unter electrodes based on MXenes and their composites have been reviewed for the development of Pt-free DSSCs. We believe that the present review article will be beneficial for the researchers working towards the development of phenolic sensors and DSSCs using MXenes and their composites as electrode materials.

Nitrogen and sulfur co-doped porous carbon obtained from direct carbonization of a renewable biomass for counter electrode of efficient dye-sensitized solar cells

It is highly necessary to fabricate cost-effective counter electrode for promoting the development and practical deployment of dye-sensitized solar cells (DSSCs). Herein, nitrogen and sulfur co-doped porous carbon (NSPC) is prepared through directly carbonizing a renewable biomass, Eupatorium fortunei Turcz., and used as an alternative to expensive Pt to fabricate low-cost counter electrode for high-performance DSSCs. Scanning electron microscopy and N2 adsorption analyses demonstrate that the obtained carbon sample displays a hierarchical pore structure containing macropore channels and well-developed mesopores formed on the wall of macropore channels. X-ray photoelectron spectroscopy measurements suggest that nitrogen and sulfur atoms are doped in the framework of as-prepared carbon sample. These favorable characteristics endow the obtained NSPC counter electrode with a superior electrocatalytic performance. Consequently, the assembled DSSC with NSPC counter electrode shows an efficiency of 8.25%, nearly matching the efficiency of the cell with conventional Pt counter electrode.

Synthesis of CuCo2S4 nanosheets and its application in dye-sensitized solar cells

CuCo2S4, a ternary sulfide and an eco-friendly thiospinel that occurs naturally as a mineral named Carrollite, has been synthesized successfully in ambient conditions at low temperatures using ultrasonication. It has yet to be reported, but the nanosheet structure obtained from the ultrasonication synthesis method employed as a counter electrode in the dye-sensitized solar cells (DSSCs) has been demonstrated. The purity, crystallinity, morphology, and structure were explored thoroughly through the medium of XRD, SEM, TEM, SAED, and EDAX, and along with this, the presence of metal sulfide bond was investigated with the FT-IR and Raman spectra, which altogether confirmed the formation of CuCo2S4 nanosheet. The as-prepared nanosheets of CuCo2S4 have shown excellent homogeneity, as expected. Also, the presence of sulfur in the synthesized CuCo2S4, which is a highly polarizable atom and of a smaller size exhibiting a higher surface area, demonstrates higher electrocatalytic activity when fabricated as a counter-electrode in DSSCs by providing an incredible short circuit current density of 31.05 mA cm−2, open circuit potential of 735 mV with good fill factor value which altogether resulted in the power conversion efficiency of 10.21 % nearer to DSSC fabricated with Platinum counter electrode under the same conditions.

Formamidinium Lead Iodide‐Based Perovskite Solar Cell Fabrication With an Electrospun‐Reduced Graphene Oxide Back Electrode: A Novel Approach

AbstractIn this work, low‐cost and simple structure perovskite solar cells (PSCs) were fabricated using formamidinium lead iodide (FAPbI3) as the light absorber and reduced graphene oxide nanofibers (rGO NFs) as the counter electrode (CE). The FAPbI3 light absorber was prepared using a two‐step solution process, whereas the rGO NFs were synthesized through a simple electrospinning method. The as‐prepared FAPbI3 and rGO NFs were characterized by high‐resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and X‐ray diffraction (XRD) pattern analysis. The surface morphology of the as‐prepared FAPbI3 and rGO NFs showed crystalline and bead‐free fiber structures, as confirmed by HRTEM and FESEM image analysis. The AFM topographical images of FAPbI3 and rGO NFs further reveal the crystalline and fiber structures. XRD pattern analysis confirmed the cubic crystalline phase of FAPbI3 and the graphitic nature of rGO NFs. From the electrochemical impedance spectroscopy studies, the PSC assembled with the FAPbI3 light absorber and rGO NFs‐based CE demonstrated an electrical conductivity of 3.64 × 10−4 S cm−1. The fabricated PSC device achieved an efficiency of 8.78% compared to the 7.49% efficiency of the device with a sputtered gold CE. This work uniquely integrates advanced materials, cost‐effective manufacturing, and enhanced efficiency in PSCs using FAPbI3 light absorbers and rGO NFs, addressing key challenges in cost and sustainability in solar technology.

Efficient Dye-Sensitized Solar Cell with Affordable Alternative to Platinum free Counter Electrode

The study focuses on MnCO3/reduced graphene oxide (rGO) composite to investigate its capability against reduction of triiodide (I3⁻), and hence to utilise its potential as a platinum free electrode in dye-sensitized solar cells (DSSCs). The MnCO3/rGO composites were prepared with varying weight percentages of rGO to identify the optimal configuration to attain enhanced catalytic performance. The MnCO3/rGO 75wt% composite exhibited the optimal catalytic reaction kinetics for converting triiodide (I3⁻) to iodide (I⁻), achieving a photon to electron conversion efficiency (PCE) of 6.62%, with a photocurrent density (Jsc) of 13.29mAcm⁻², voltage (Voc) of 0.76V, and a fill factor (FF) of 0.65 at without load. This output performance is on par with that of to that of a conventional platinum (Pt) Counter Electrode, which achieved a PCE of 6.98%. The findings indicate that MnCO3/rGO 75wt% composite shows significant promise, cost-effective alternative to Pt, offering efficient performance and improved material sustainability.

Improvement in the performance of indium free dye sensitized solar cell by the use of polyaniline composite

The photovoltaic study of the fabricated dye sensitized solar cells is revealed in this paper. To provide indium free approach, fluorine doped tin oxide (FTO) and aluminium doped zinc oxide (AZO) glass substrate were used as charge collectors for counter electrodes and photoanode respectively. Also, a novel and natural mixed dye was used as sensitizer and mixture of doped polymer (polyaniline with metallic oxides of tin, vanadium and cerium) and iodide-triiodide couple was utilized as electrolyte for the cell. Optical band gap and light absorption performance of dyes were studied by ultraviolet-visible (UV-vis) spectroscopy. Surface morphology and elemental composition of polymer composites was studied using scanning electron microscopic (SEM) with energy dispersive X ray (EDX) analysis. Phase analysis of the composites was determined by X-ray diffraction and thermal behavior with the help of thermo gravimetric analysis (TGA). Photovoltaic characteristics (I-V) and induced photon to current efficiency (IPCE) measurements were also investigated. Highest IPCE of 17.7% was observed when polyaniline was doped with oxide of vanadium. Hence an efficient, green, indium free and novel cell is fabricated by the usage of different charge collector substrate, natural dye sensitizer and quasi solid-state electrolyte.

All-solid-state electrochemical marine sensors based on Na3V2(PO4)3@Na4Zr2Si3O12 solid-state reference electrodes

In this study, Na4Zr2Si3O12 (NZS) solid electrolyte was prepared using an elevated-temperature solid-state method. After heating under supercritical conditions (i.e., 400 °C and 40 MPa), the structure and performance stability of the as-fabricated NZS solid electrolyte were evaluated applying scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS). A new all-solid-state reference electrode, combining Na3V2(PO4)3(NVP) with NZS (NVP@NZS), was developed, and its electrochemical properties were investigated. The prepared reference electrode demonstrated steady potential in both simulated seawater and buffer solutions across a range of pH values and different salt solutions. The reference electrode, integrated with an Ir/IrO2 working electrode, was used to construct an all-solid-state potentiometric pH sensor. This sensor demonstrated a strong linear related response when measuring the pH of both aqueous solutions and simulated seawater samples. Additionally, an ion sensor based on anodic stripping voltammetry, constructed with the assembled solid-state reference electrode, a platinum counter electrode, and a gold-mercury working electrode, was utilized to measure Cu2+ and S2− ions in both aqueous solutions and simulated seawater samples. These all-solid-state electrochemical sensors, incorporating the NVP@NZS solid-state reference electrode, demonstrated a small detection threshold, excellent linear correlation (R2 > 0.99), and a broad detection range, making them well-suited for chemical analysis in challenging marine environments.

Dual purpose of graphene decorated with Cu3SnS4 as a counter electrode for dye sensitized solar cells and degradation of tetracycline antibiotics

Dual purpose of graphene decorated with Cu3SnS4 as a counter electrode for dye sensitized solar cells and degradation of tetracycline antibiotics

A gated highly variable pseudocapacitor based on redox-window control (G-CAPode)

Iontronic architectures operate via multiple ions or redox processes mimicking neural systems capable to operate with complex ions and biological transmitters with high energy efficiency. Recently, ultracapacitors have emerged as novel iontronic switchable devices with a high on/off ratio. We propose a novel iontronic device offering flexible control of the current output of a switchable electrochemical capacitor diode (CAPode) by introducing an additional "gate" electrode. This device mimics field-effect transistor (FET) semiconductors in controlling current output and recovers energy consumed during the forward charging, marking a significant breakthrough. A recently developed unidirectional CAPode system (Ni3Bi2S2@Ni I 1 mol L-1 KOH I AC@Ni) serves as the “working” capacitor (W-Cap) in the novel architecture. The proposed G-CAPode (gate-controlled CAPode) features a third voltage-controlled connection between the “gate” and the counter electrode of the W-Cap. By varying this third voltage channel the electrodes of W-Cap are shifted in potential toward negative or positive potential windows. Hence, by external voltage control the rectification ratios and blocking efficacy can be tuned which is essential for fully controlling the output signal in logic gates. A new circuit monitors the current and potential distribution of the “NOT” gate: The G-CAPode system exhibits transistor-like characteristics with a -1.2 V bias. This investigation highlights the versatility of the G-CAPode system across applications where transistor-like behavior and accurate current regulation are beneficial, promising advancements in ionologic devices, sensors, and energy storage systems.

Next-generation counter electrodes for dye-sensitized solar cells: A comprehensive overview

Next-generation counter electrodes for dye-sensitized solar cells: A comprehensive overview

Optimization of electrochromic Mo doping WO3 films: A study on dual-phase stacked structures for energy-efficient smart windows

Amorphous tungsten trioxide (a-WO3) films were prepared on ITO conductive glass via electrodeposition and subsequently crystallized to obtain crystalline WO3 (c-WO3) films by heating a-WO3. A dual-phase stacked WO3 film was fabricated by covering Mo-a-WO3 film onto c-WO3/ITO substrate using electrodeposition and thermal-assisted electrodeposition methods, respectively. Optimization of electrochromic performance was achieved by varying Mo doping levels (0∼5 atom%). Results demonstrate that appropriate Mo doping (3 atom%) enhances the electrochromic properties of a-WO3 films. Mo doping introduced structural distortions that reduced energy barriers and enhanced ion mobility, leading to improved electrochemical and electrochromic properties. The intermediate c-WO3 layer improves adhesion between a-WO3 top film and ITO glass substrate, while the porous structure of a-WO3 layer increases the number of active sites for electrochromic reactions. Mo3-a-WO3/c-WO3 dual-phase stacked film with doping 3 atom% Mo shows an optical modulation range of 83.4 % at 633 nm, a coloration efficiency of 74.3 cm2/C, rapid response time (bleaching/coloration: 3.4 s/6.1 s), and 86.6 % retention of its maximum current density after 2000 cycles, respectively. The high oxidation ion diffusion coefficient (3.53 × 10−10 cm2/s) and reduction diffusion coefficient (1.55 × 10−10 cm2/s) were also observed. This dual-phase stacked film shows significant improvements in electrochromic performance due to the synergistic effects between the dual phases and Mo-doping. Electrochromic device (ECD) assembled with Mo3-a-WO3/c-WO3 dual-phase films as the working electrode, ITO glass as the counter electrode, and 1 mol/L LiClO4/PC solution as the electrolyte exhibited an optical modulation range of 74.2 % and response time (bleaching/ coloring) of 6.8 s/3.7 s. These findings confirm that ECD with Mo-a-WO3/c-WO3 dual-phase films offer excellent electrochromic performance.

Laminated Carbon Materials Doped with B, N, and P Elements as DSSCs Counter Electrodes

Laminated Carbon Materials Doped with B, N, and P Elements as DSSCs Counter Electrodes

Oxygen enriched PAni-based counter electrode network toward efficient dye-sensitized solar cells (DSSCs)

Dye-sensitized solar cells (DSSCs) have great potential as a renewable energy technology assisting combat climate change due to its low cost, adaptability, and sustainability. Oxygen plasma ion doping is a promising strategy to improve the capacity of a low-cost, platinum-free counter-electrodes (CEs) to absorb photons and drive high-performance DSSCs via generating an abundance of active absorption sites. In this instance, novel PAni–ZnO (PZ) composite layers were designed as a CE material and received various in-situ oxygen plasma dosages, including 0, 2, 4, 6, 8, and 10 min, to improve their physiochemical and microstructural feature for the first time, to the best of our knowledge. Physical evaluations of the microstructure, porosity, morphology, contact angle, roughness, electrical, and optical, electrochemical impedance spectroscopy (EIS) features of CEs were conducted in along with an evaluation of J–V variables. Compared to pristine CE substance, the surface nature of the modified hybrids was gradually enhanced as the plasma level rose, reaching an optimum after 8 min (i.e. 0.2 µm for average pore size and average roughness Ra = 7.21 µm). Expanded plasma treatment doses also improved PV cell performance even further: after 4 min at a plasma level, η = 5.41% was obtained, and after 6 min in a oxygen plasma environment, η = 5.81% was obtained. Mixing high energetic plasma ions increased the mobility of charge carriers in PAni composites along with lowered charge carrier recombination through generating an environment that was conducive to charge dissociation. Therefore, longer lifespans and more effective charge transfer inside the photovoltaic cell as a consequence of the increased mobility less resistive losses. In this respect, following 8 min of plasma surface modification of the PZ CE, the optimized efficiency of 6.31% and Jsc of 15.6 mA/cm2 were obtained. The improvement in efficiency equated to a proportion growth of 77% versus a pristine one. This gain was explained by the reality that suffusing a quantity of oxygen plasma free radicals into the PAni system developed continuous channels that enabled the mixture to move electrons more rapidly, hence raising the photovoltaic efficiency. Overall, this study highlights the advantages of regulating heteroatom species and their co-doping, offering a new perspective for the application of heteroatom-doped CE in DSSCs.

Fully biodegradable electrochromic display for disposable patch

Flexible and biodegradable electronics have emerged as a promising solution for escalating electronic waste issue caused by the rapid development of skin patch electronics. Fully biodegradable displays are essential for visualizing biological/physical/chemical/electrochemical signals measured by a wide range of skin patch electronics. Here we propose fully biodegradable electrochromic display providing low operating voltage and low power consumption. The biodegradable transparent conductive electrode was fabricated by transferring free-standing tungsten nanomesh onto poly lactic-co-glycolic acid substrate using electrospinning templating, minimizing damage to the substrate. Electrochromic layer was tungsten oxide which is biodegradable, and a ferrocyanide/ferricyanide redox agent was utilized as a counter electrode reaction to enhance operational stability in an aqueous electrolyte by reducing operating voltage and side reactions. This display successfully visualized diverse signals from various biodegradable electronics such as UV sensors and electrochemical transistors, and finally underwent eco-friendly degradation in phosphate-buffered saline or soil under mild conditions.