Working Electrode Material Research Articles

Layer-by-layer WS2-Cr heterojunction as a positive working electrode material for high-performance supercapattery applications

This study investigates the impact on the electrochemical performance of pristine sputtered WS2 through the strategic integration of a highly conductive chromium interfacial layer. This study involves the fabrication of two different samples via magnetron sputtering: type I, WS2-sputtered and type II, WS2/Cr (sputtering of Cr as an interfacial layer between sputtered-WS2 and NF). Afterward, structural, topographic and elemental composition of as-synthesized samples were inspected via XRD, SEM, Raman, and EDX. Following this, the energy storage performance were evaluated by employing CV, GCD, and EIS in three and two electrode assembly sequentially. In three electrode testing WS2 and WS2/Cr exhibited the specific capacity (Qs) of 661.79C g−1 and 1600C g−1 at 3 mV/s along with the capacity retention of 61.37 % (WS2) and 83.04 % (WS2/Cr), respectively. Similarly, through GCD WS2 shows the Qs of 637.34C g−1 at 0.8 A/g conversely, WS2/Cr exhibited the Qs of 1220C g−1 at 1.3 A/g. Besides, the WS2/Cr demonstrated long-term longevity (capacity retention of 83.13 %) after 5000 GCD cycles. Based on exclusive electrochemical performance of type II of two samples, an asymmetric battery-type hybrid supercapacitor (WS2/Cr//AC) was fabricated by incorporating WS2/Cr and activated carbon (AC) as working and counter electrodes. WS2/Cr//AC revealed the Qs of 352C g−1 (785F g-1) at 0.7 A/g. Besides, it deliberately delivered 81 Wh kg−1 and 1750 W kg−1 energy and power. The device exhibits excellent cyclic stability by maintaining its capacity after 5000 GCD cycles and illustrated 87.30 % capacity retention. Following that, semi-empirical approach was applied to quantify the capacitive and diffusive currents’ contribution in overall device’s performance. The results highlight that WS2/Cr hold colossal potential to fill the proficiency gap between presently keep-going devices and stern demands of future energy storage applications.

Sustainable organic electrodes using black soldier fly-derived melanin for zinc-ion hybrid capacitors

Pressing environmental challenges require focused research on sustainable solutions in the domains of energy, water, food, land, and climate. The pigment eumelanin has recently been positioned as a promising candidate for solving issues in health, sensors, and energy storage. However, the low solubility of eumelanin in aqueous solvents, difficult film processibility, and high cost have hindered the material from wide deployment. Here, we propose melanin extracted from the black soldier fly, Hermetia illucens (Mel-BSF), as a sustainable alternative for the preparation of organic electrodes in energy storage applications. Mel-BSF displays pseudocapacitive behaviour with a high potential window, good electrochemical stability, and higher maximum capacity (91.8 mAh g−1) compared to synthetic eumelanin (17.3 mAh g−1) as the working electrode material in zinc-ion hybrid capacitors using an ionic liquid electrolyte. Structural and surface investigations reveal that additional aliphatic compounds, potentially lipids present after Mel-BSF refinement, significantly increase the film stability and redox centre availability.

Graphene/MWCNT/copper-nanoparticle fabricated printed electrode for diclofenac detection in milk and drinking water: Electrochemical and in-silico analysis

This study investigates the electrochemical sensing of Diclofenac sodium. A single carbon printed electrode was modified with the combination of graphene (GRP), multi-walled carbon nanotube (MWCNT), and copper-nanoparticle (CuNP) blended with oleic acid (OA) (i.e. CuNP@OA) as working electrode material of the three-electrode system (i.e. GRP-MWCNT-CuNP@OA). Here, copper nanoparticles, being responsible for catalysis, are embedded on the matrix comprising of GRP and MWCNT which serves as the conductive matrix material for electrode. The OA acts as a stabilising agent for the active CuNPs. The chemical sensitivity feature (in terms of binding interaction) of the GRP-MWCNT-CuNP@OA composite model interacting with the Diclofenac has been examined by implementing quantum chemical calculation approaches like molecular modelling, semi-empirical, QTAIM, and NCI-plot based tools. Some useful and important properties have also been examined using electronic parameters such as HOMO, LUMO, HOMO-LUMO gap, charge transfer (CT), QTAIM-based topological parameters, etc. which could indeed be helpful for the experimentalists in understanding the structural, stability/energetics, and electronic features of the probed composite models at nano-level. Further, the characterization of the composite was carried out through some sophisticated characterization techniques like scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), and powder XRD. Cyclic voltammetry (CV) is used for studying stability of the composite and chemical kinetics of the oxidation of Diclofenac sodium. Differential pulse voltammetry (DPV) was used to evaluate the sensing performance of the above-mentioned material by determining the lower range detection limit of Diclofenac (57.7 nM) and linear range (17.41 μM – 206.45 μM) of the electrochemical sensor. Further to validate the results obtained, real sample analysis was performed using the developed electrode in drinking water and milk spiked with Diclofenac.

Evaluation of Transducer Elements Based on Different Material Configurations for Aptamer-Based Electrochemical Biosensors.

The selection of an appropriate transducer is a key element in biosensor development. Currently, a wide variety of substrates and working electrode materials utilizing different fabrication techniques are used in the field of biosensors. In the frame of this study, the following three specific material configurations with gold-finish layers were investigated regarding their efficacy to be used as electrochemical (EC) biosensors: (I) a silicone-based sensor substrate with a layer configuration of 50 nm SiO/50 nm SiN/100 nm Au/30-50 nm WTi/140 nm SiO/bulk Si); (II) polyethylene naphthalate (PEN) with a gold inkjet-printed layer; and (III) polyethylene terephthalate (PET) with a screen-printed gold layer. Electrodes were characterized using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) to evaluate their performance as electrochemical transducers in an aptamer-based biosensor for the detection of cardiac troponin I using the redox molecule hexacyanoferrade/hexacyaniferrade (K3[Fe (CN)6]/K4[Fe (CN)6]. Baseline signals were obtained from clean electrodes after a specific cleaning procedure and after functionalization with the thiolate cardiac troponin I aptamers "Tro4" and "Tro6". With the goal of improving the PEN-based and PET-based performance, sintered PEN-based samples and PET-based samples with a carbon or silver layer under the gold were studied. The effect of a high number of immobilized aptamers will be tested in further work using the PEN-based sample. In this study, the charge-transfer resistance (Rct), anodic peak height (Ipa), cathodic peak height (Ipc) and peak separation (∆E) were determined. The PEN-based electrodes demonstrated better biosensor properties such as lower initial Rct values, a greater change in Rct after the immobilization of the Tro4 aptamer on its surface, higher Ipc and Ipa values and lower ∆E, which correlated with a higher number of immobilized aptamers compared with the other two types of samples functionalized using the same procedure.

GO@ZnO/CuO sensitive selective detection of lactic acid photoelectrochemistry design of sensors

The photoelectrochemical lactate sensor is a sensor that integrates electrochemical and optoelectronic principles for detecting lactate concentration. Lactic acid is a metabolic product in organisms, and its concentration changes are closely related to the health status of the body. The development of highly sensitive and selective lactic acid sensors is of great significance for fields such as medical diagnosis, exercise physiology, and the food industry. This study used a simple hydrothermal method to prepare CuO and ZnO composite electrodes, with GO flake structures covering the surface of nanoparticles, providing a larger surface area and enhanced interaction. Advanced nanomaterials were used as the working electrode materials for electrochemical sensors, which generate current signals through specific reactions with lactic acid to enhance the sensitivity and stability of the sensors. The limit of detection (LOD) is 0.203 mM. Efficient monitoring of lactate concentration provides a novel and multifunctional method, which is of great significance for promoting research in the fields of medicine and life sciences.

Electrochemical investigation of phosphorous and boron heteroatoms incorporated reduced graphene oxide electrode material for supercapacitor applications

Graphene-based nanomaterials are becoming common components for consumer products due to their outstanding charge carrier ability, high surface area, high thermal stability, and great potential for environmental decontamination. Nowadays, heteroatoms added carbon allotropes are providing better electrochemical performances in the field of supercapacitors as an electrode material. In this present work, boron and phosphorus heteroatoms were introduced in the network of reduced graphene oxide to increase the capacitance of the supercapacitor. The B and P incorporated rGO (PB-rGO) electrode material was prepared by the hydrothermal method. The properties of the electrode material were analyzed using structural, morphological, and elemental analysis. The prepared electrode material was used as a working electrode material in supercapacitors. In 1 M H2SO4 aqueous electrolyte medium, a maximum specific capacitance of 436 F g−1 was found for PB-rGO in a three-electrode configuration. In a symmetric configuration, a power density of 394 W kg−1 and an energy density of 12.48 Wh kg−1 were observed for the PB-rGO electrode. The cyclic stability analysis showed 97.6 % retention after 10,000 cycles at the current density of 3 A g−1.

Exploration of facile hydrothermally produced pure nickel oxide nanostructures as an effective electrode material for the enhanced supercapacitor applications

Abstract This research work concerns with the magnetic and electrochemical characteristics of hydrothermally prepared nickel oxide (NiO) nanoparticles for their use as working electrode material in supercapacitor. Through the use of thermal gravimetric (TG-DTA), the thermal stability and heat adsorption/desorption characteristics of the as-produced NiO nanoparticles were examined. By using X-ray diffraction (XRD) technique at ambient, 600 °C and 800 °C annealing temperatures, the trigonal and cubic structure of the as prepared and annealed nanoparticles was discovered. The spherical and cubic morphology of the as synthesized and annealed (800 °C) NiO nanoparticles was confirmed through field emission scanning electron microscope (FESEM), energy dispersive X-ray (EDAX) analysis. The functional groups, optical bandgap energy, surface chemistry, specific surface area and superparamagnetic behavior of the annealed (800 °C) NiO nanoparticles were determined through Fourier transform infra-red (FT-IR), UV-DRS, XPS, BET and VSM characterization approaches, respectively. At the lowest scan rates of 10 mVs−1 and 0.5 Ag−1, the pseudocapacitive behavior was noticed utilizing CV and GCD analyses. An excellent electrical conductivity for the supercapacitor application was also shown by the Nyquist plot of the produced NiO electrode.

MOF-based Sensing Materials for Non-enzymatic Glucose Sensors

<p>Diabetes mellitus is one of the common chronic diseases, seriously threating to human health. The continuous monitoring of blood glucose concentration can effectively prevent diabetic diseases. The sensing performance of glucose non-enzymatic sensors is mainly determined by working electrode materials. Metal–organic frameworks (MOFs) are recognized as promising candidate for glucose sensor application, due to its large surface areas, ordered porous structure and nearly infinite designability. In this review, the sensing performance, research progress and future challenge of non-enzymatic glucose sensors based on MOF-based materials in recent years are presented. We hope that this review would provide valuable technology guidance for high performance non-enzymatic glucose sensors based on MOFs.</p>

DSSC Fundamentals and Optimization Materials :A Review

Recently, researchers are focusing on renewable energy sources such as wind energy, Hydro-thermal energy, and solar energy. In this research article DSSC fundamentals and optimized materials are discussed and compared. The maximum efficiency reported by the researcher is 12% using Ru (II) dyes. The efficiency of DSSC depends on the various factors such as working electrode material, counter electrode material, dye used in preparation of solar cell are discussed. The simplest technique used for fabrication of DSSC solar cell is doctor blade method also discussed in this review article.

Quantitative Analysis of CO2 Evolution in an Alkaline Electrolyte Solution By Differential Electrochemical Mass Spectroscopy

CO2 is involved in various main and side reactions of electrochemical energy devices, such as carbon corrosion reactions and alcohol oxidation reactions. Differential electrochemical mass spectroscopy (DEMS) has been intensively applied in acidic electrolyte solutions to analyze these reactions. DEMS is the in-situ electrochemical measurement technique to analyze volatile species with the mass spectrometer (MS). However, the applications of DEMS to alkaline electrolyte solutions have been limited due to the high solubility of CO2 in alkaline solutions. While "conventional DEMS cells," where porous thin-film working electrodes are formed onto polytetrafluoroethylene (PTFE) membrane interface, can quantitatively analyze CO2 that has not dissolved into the electrolyte yet [1], the working electrode materials are limited to those that can be deposited on porous PTFE membrane as porous thin-films. Recently, Möller et al. have developed the DEMS system, which can detect CO2 from general planer electrodes coated by catalyst powders by combining a neutralizer and "dual thin-layer flow cell" [2]. However, due to the relatively low detection limit, quantitative analysis of evolved CO2 has not been accomplished. In this study, we attempt to use high surface area electrodes to enhance the MS signal of CO2 to enable quantitative analysis of evolved CO2. To suppress the in-plane reaction distribution in the flow cell, we integrated an anion exchange membrane into the cell and arranged the counter electrode opposing the working electrode [3] (Fig. 1 (a)).CO-stripping voltammetry was performed to evaluate the CO2 detectability of the constructed DEMS system. The DEMS cell was composed of a commercial Pt/C electrode as the working electrode, a commercial Hg/HgO electrode as the reference electrode, a Pt mesh as the reference electrode, 1 mol dm–3 KOH aq as the electrolyte solution, and 1 mol dm–3 H2SO4 aq as the neutralizer. Figure 1 (b) shows the CO-stripping voltammogram and corresponding MS signal of CO2 (m/z = 44). MS signal of CO2 accompanied by the anodic CO oxidation current is clearly observed from 0.6 to 1.2 V vs. RHE. The calibration constant, which correlates the MS signal of CO2 to partial current for CO2 evolution reaction, is successfully obtained as 2.2 × 10–10, which shows that the DEMS system established in this study can quantitatively analyze CO2. Applications to the carbon corrosion reactions are also presented at the site.

An Electrochemical Immunosensor with PEDOT: PSS/MWCNTs-COOH Nanocomposites as a Modified Working Electrode Material for Detecting Tau-441

The progression of Alzheimer’s disease (AD) is positively correlated with the phosphorylation damage of Tau-441 protein, which is the marker with the most potential for the early detection of AD. The low content of Tau-441 in human serum is a major difficulty for the realization of content detection. Herein, we prepared an electrochemical immunosensor modified with Poly(3,4-ethylene-dioxythiophene)-poly (styrene sulfonate) (PEDOT: PSS)/Carboxylated multi-walled carbon nanotube (MWCNTs-COOH) nanocomposites based on electrochemical immunoassay technology for the low-concentration detection of Tau-441. The immunosensor based on the nanocomposite can take advantage of the characteristics of conductive polymers to achieve electrical signal amplification and use MWCNTs-COOH to increase the contact area of the active site and bond with the Tau-441 antibodies on the electrode. The physicochemical and electrical properties of PEDOT: PSS/MWCNTs-COOH were studied by in situ characterization techniques and electrochemical characterization methods, indicating that the immunosensor has high selectivity and sensitivity to the Tau-441 immune reaction. Under optimized optimal conditions, the electrochemical immunosensor detected a range of concentrations of Tau-441 to obtain a low detection of limit (0.0074 ng mL−1) and demonstrated good detection performance through actual human serum sample testing experiments. Therefore, the study provides an effective reference value for the early diagnosis of AD.

Controlling the Cooling Rate of Hydrothermal Synthesis to Enhance the Supercapacitive Properties of β-Nickel Hydroxide Electrode Materials.

The demand for power storage devices with good quality, fast charging and high energy density is becoming more and more urgent in today's electronic technology. For batteries and traditional capacitors, it is an insurmountable challenge to combine fast charging and discharging, large capacitance and long-life properties. The characteristics of supercapacitors can meet all the above requirements at the same time. In this study, a simple one-step hydrothermal method was successfully used to grow β-nickel hydroxide nanocone particles directly on the 3D foamed nickel substrate as a working electrode material for supercapacitors. After growing β-nickel hydroxide crystals on 3D foamed nickel substrate, by controlling the cooling rate, a well-crystalized β-nickel hydroxide with good capacitance characteristics can be obtained. Cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) were used to analyze the capacitance characteristics of the β-nickel hydroxide electrode. The research results show that the specific capacitance value of the β-Ni(OH)2/3D nickel foam electrode material prepared at the cooling rate of 10 °C/h can reach 539 F/g with the charge-discharge test at a current density of 3 A/g. After 1000 continuous charge and discharge cycles, the material still retains 94.1% of the specific capacitance value.

Stability of Single Gold Atoms on Defective and Doped Diamond Surfaces.

Polycrystalline boron-doped diamond (BDD) is widely used as a working electrode material in electrochemistry, and its properties, such as its stability, make it an appealing support material for nanostructures in electrocatalytic applications. Recent experiments have shown that electrodeposition can lead to the creation of stable small nanoclusters and even single gold adatoms on the BDD surfaces. We investigate the adsorption energy and kinetic stability of single gold atoms adsorbed onto an atomistic model of BDD surfaces by using density functional theory. The surface model is constructed using hybrid quantum mechanics/molecular mechanics embedding techniques and is based on an oxygen-terminated diamond (110) surface. We use the hybrid quantum mechanics/molecular mechanics method to assess the ability of different density functional approximations to predict the adsorption structure, energy, and barrier for diffusion on pristine and defective surfaces. We find that surface defects (vacancies and surface dopants) strongly anchor adatoms on vacancy sites. We further investigated the thermal stability of gold adatoms, which reveals high barriers associated with lateral diffusion away from the vacancy site. The result provides an explanation for the high stability of experimentally imaged single gold adatoms on BDD and a starting point to investigate the early stages of nucleation during metal surface deposition.

Biosensor development for low-level acetaldehyde gas detection using mesoporous carbon electrode printed on a porous polyimide film

Acetaldehyde, which is an intermediate product of alcohol metabolism, is known to induce symptoms, including alcohol flushing, vomiting, and headaches in humans. Therefore, real-time monitoring of acetaldehyde levels is crucial to mitigating these health issues. However, current methods for detecting low-concentration gases necessitate the use of complex measurement equipment. In this study, we developed a low-cost, low-detection-limit, enzyme-based electrochemical biosensor for acetaldehyde gas detection that does not require sophisticated equipment. The sensor was constructed by screen-printing electrodes onto a porous polyimide film, using grafted MgO-templated carbon (GMgOC) as working electrode material, carbon for the counter electrode, and silver/silver chloride for the reference electrode. Pyrroloquinoline-quinone-dependent aldehyde dehydrogenase was immobilized on the working electrode, and a chamber was attached to the electrode chip and filled with 1-methoxy-5-methylphenazinium methyl sulfate solution. The sensor can be used to measure acetaldehyde gas concentrations from 0.02 to 0.1 ppm, making it suitable for monitoring human skin gas. This low detection limit was achieved by delivering the analyte through the porous polyimide film on which the electrodes were printed and accumulating acetaldehyde in the mesoporous GMgOC of the working electrode. This mechanism suggests that this sensor design can be adapted to develop other low-detection limit gas sensors, such as those for screening skin gas biomarkers.

The Effect of the Working Electrode Material Based on Pt/SnO2(Sb) on the Properties of Hydrogen and Carbon-Monoxide Sensors

The effect of the platinum content (3–10 wt %) in the Pt/SnO2(Sb)-based working-electrode material on the properties (sensitivity, high-speed performance, recovery time) of solid-state potentiometric gas sensors for hydrogen and carbon monoxide including their simultaneous presence in air is studied. Sensors with 5% Pt demonstrate the best characteristics: the efficient carbon-monoxide detection for its concentration from 0.01 to 1 vol %; no effect of hydrogen present in the CO + air mixture in concentrations comparable with the CO concentration; the shortest relaxation time (~30 s at 1% CO).

The Effect of the Working Electrode Material Based on Pt/SnO2(Sb) on the Properties of Hydrogen and Carbon-Monoxide Sensors

The Effect of the Working Electrode Material Based on Pt/SnO2(Sb) on the Properties of Hydrogen and Carbon-Monoxide Sensors

The Importance of Electrode Material in Bioelectronic Electrophoretic Ion Pumps

AbstractBioelectronic ion pumps deliver ions and biomolecules from a source to a target biological system with high spatiotemporal control for bioengineering and regenerative medicine applications. A voltage between a working electrode and a reference/counter electrode delivers the charged ions and biomolecules from a source to the desired target. The source and the target are separated by an ion exchange membrane so that only the charged molecules of interest are delivered. Future wearable and implantable applications require high efficiency of delivery to minimize power consumption. The majority of recent efforts on improving ion pump efficiency have focused on optimizing the ion exchange membrane. However, the contribution of the working electrode material to the ion pump efficiency has been mostly overlooked. This work identifies how changing the working electrode material greatly affects the efficiency of delivery in ion pumps. With an electrical circuit model analysis, voltammetry studies on silver, platinum, and palladium hydride working electrodes, and implementation of the Butler–Volmer equation, results show that the material‐dependent equilibrium potential at the working electrode surface has a large impact on ion pump efficiency. With this knowledge, a simple predictive model to optimize the working electrode material for delivering each specific ion or molecule of interest is designed.

Surfactant-assisted hydrothermal synthesis of large surface area nickel nanoparticles for electrochemical applications

A large surface area is an imperative parameter for electrocatalytic materials applied in electrochemical devices. In the present work, Ni nanoparticles were synthesized by hydrothermal method using three surfactants: sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and polyvinyl pyrrolidone (PVP) and two base media, i.e., sodium hydroxide (NaOH) and ammonium hydroxide (NH4OH). We investigated the effects of different surfactants and base mediums on Ni nanoparticles' crystallite size, particle size, and surface area. Experimental results revealed that Ni nanoparticles with smaller particle sizes (50–90 nm) and large surface area (28.4–64 m2/g) were obtained when NaOH was used as the base medium with all surfactants. Further, a high specific capacitance of 417 F/g, minimum charge transfer resistance of 490 Ω, and 91 % capacitance retention demonstrated that Ni nanoparticles obtained using PVP in NaOH could be applied as potential working electrode material in enhancing the performance of supercapacitor devices.

Electrochemical catalyst 4-Acetamido-TEMPO oxidation degumming of scutched flax tow (SFT): Promoting of lignin depolymerization and restraining of cellulose degradation

Bast fiber degumming can be achieved in TEMPO/NaClO/NaBr, TEMPO/laccase system, however, large amounts of harmful chemicals and/or expensive enzymes used in these systems caused high pressure on the environment and economic cost. To solve this problem, electrochemical catalyst TEMPO system (ECTS) was established for the degumming of scutched flax tow. Results showed that successful degumming could be achieved under the assisting method which could provide shearing force to the system (e.g., stirring, shaking, etc.), but could not be achieved with assisting method providing other kinds of force (e.g., ultrasound, electrode covering, etc.). The use of proton exchange membrane could improve the degumming efficiency. The reaction efficiency of ECTS decreased in the order of NHPI > 4- Acetamido -TEMPO > TEMPO; working electrode material of titanium ruthenium iridium > graphite > glassy carbon; and the rising of working electrode area. Under the optimal reaction condition (5 × 5 cm2 graphite flake working electrode, shaking speed 700 rpm, 0.2 mol/L 4- Acetamido -TEMPO, 0.25 mol/L electrolyte, pH 11.0, 2.1 V, 120 min, 85 °C), the cellulose content, lignin content, tenacity of the resulted SFT reached 82.3%, 1.8% and 1200 N/g, respectively. The waste water COD value of ECTS was 61.7% lower than that of TEMPO/NaClO/NaBr degumming, and similar with that of TEMPO/laccase degumming.

Interleaved Electroactive Molecules into LDH Working on Both Electrodes of an Aqueous Battery-Type Device.

By selecting two electroactive species immobilized in a layered double hydroxide backbone (LDH) host, one able to act as a positive electrode material and the other as a negative one, it was possible to match their capacity to design an innovative energy storage device. Each electrode material is based on electroactive species, riboflavin phosphate (RF) on one side and ferrocene carboxylate (FCm) on the other, both interleaved into a layered double hydroxide (LDH) host structure to avoid any possible molecule migration and instability. The intercalation of the electroactive guest molecules is demonstrated by X-ray diffraction with the observation of an interlayer LDH spacing of about 2 nm in each case. When successfully hosted into LDH interlayer space, the electrochemical behavior of each hybrid assembly was scrutinized separately in aqueous electrolyte to characterize the redox reaction occurring upon cycling and found to be a rapid faradic type. Both electrode materials were placed face to face to achieve a new aqueous battery (16C rate) that provides a first cycle-capacity of about 7 mAh per gram of working electrode material LDH/FCm at 10 mV/s over a voltage window of 2.2 V in 1M sodium acetate, thus validating the hybrid LDH host approach on both electrode materials even if the cyclability of the assembly has not yet been met.