Electrochemical Workstation Research Articles

Microstructure and Wear and Corrosion Resistance of CoCrFeMoNiSix (x = 0.25, 0.50, 0.75) HEACs Prepared by Plasma Cladding

CoCrFeMoNiSix (x = 0.25, 0.50, 0.75) HEACs were successfully prepared on Q235 steel substrates by the plasma cladding method. The phase structure, microstructure, element distribution, and wear and corrosion resistance of these coatings were investigated by XRD, OM, SEM, EDS, a friction and wear tester, and an electrochemical workstation. The results show that the CoCrFeMoNiSix (x = 0.25, 0.50, 0.75) coatings are composed of a major FCC phase and minor BCC phase. With an increase in Si content, the lattice constant and cell volume of both phases and the BCC phase content in these alloys gradually increase, while the enthalpy of mixing, Gibbs free energy, atomic radius difference, VEC, and phase density decrease. All the three alloys exhibit typical dendritic structures. With an increase in Si content, the enrichment of Mo and Si in the interdendrite region is significantly reduced. The friction coefficients of CoCrFeMoNiSix (x = 0.25, 0.50, 0.75) HEACs show a trend of first increasing, then decreasing, and gradually stabilizing with an increase in time, and are 0.604, 0.526, and 0.534, respectively. The wear resistance of the three alloys is mainly related to the changes in crystallinity and high-strength BCC phase content caused by different Si contents. The polarization curves of CoCrFeMoNiSix (x = 0.25, 0.50, 0.75) high-entropy alloy coatings show an obvious passivation zone, and the corrosion resistance is significantly better than that of Q235 steel substrate. The CoCrFeMoNiSi0.75 coating has the highest self-corrosion potential, smallest self-corrosion current, largest capacitive reactance arc radius, and best corrosion resistance in a 3.5% NaCl solution.

Aptamer-antibody sandwich immunosensor for electrochemical detection of FT4.

Anaptamer-antibody sandwich electrochemical immunosensor was studied. Fe3O4/MWCNTs-COOH/Nafion was modified and fixed on a glassy carbon electrode to amplify electrical signals. The antibody was coupled with AuNPs to form conjugates. It captures the target free thyroxine (FT4) and forms antibody-AuNPs/FT4 macromolecular complexes. The complex is then captured by the aptamer on the glassy carbon electrode and detected by the electrochemical workstation using differential pulse voltammetry (DPV). Under the best conditions, the prepared sensor showed a linear relationship in the concentration range 0.1 to 105 pg/mL and the detection limit (LOD) was 0.04 pg/mL. The sensor can enhance the adsorption capacity of target FT4 and detect FT4 stably and withhigh selectivity. The aptamers and antibodies are free from additional modifications. In addition, the high recovery of the proposed sensor was verified by testing the human serum samples. The immunosensor has the advantages of simple operation, rapid recognition process, and short response time. These results indicate that the immunosensor is expected to achieve rapid and effective detection of FT4 in early pregnancy and evaluate thyroid function in the future. The research ideas of this work will also be applicable to the detection of other small molecules and provide ideas for the detection of other substances.

Non-Invasive Detection of Interferon-Gamma in Sweat Using a Wearable DNA Hydrogel-Based Electrochemical Sensor

Monitoring of immune factors, including interferon-gamma (IFN-γ), holds great importance for understanding immune responses and disease diagnosis. Wearable sensors enable continuous and non-invasive detection of immune markers in sweat, drawing significant attention to their potential in real-time health monitoring and personalized medicine. Among these, electrochemical sensors are particularly advantageous, due to their excellent signal responsiveness, cost-effectiveness, miniaturization, and broad applicability, making them ideal for constructing wearable sweat sensors. In this study, we present a flexible and sensitive wearable platform for the detection of IFN-γ, utilizing a DNA hydrogel with favorable loading performance and sample collection capability, and the application of mobile software achieves immediate data analysis and processing. This platform integrates three-dimensional DNA hydrogel functionalized with IFN-γ-specific aptamers for precise target recognition and efficient sweat collection. Signal amplification is achieved through target-triggered catalytic hairpin assembly (CHA), with DNA hairpins remarkably enhancing sensitivity. Ferrocene-labeled reporting strands immobilized on a screen-printed carbon electrode are displayed via CHA-mediated strand displacement, leading to a measurable reduction in electrical signals. These changes are transmitted to a custom-developed mobile application via a portable electrochemical workstation for real-time data analysis and recording. This wearable sensor platform combines the specificity of DNA aptamers, advanced signal amplification, and the convenience of mobile data processing. It offers a high-sensitivity approach to detecting low-abundance targets in sweat, paving the way for new applications in point-of-care diagnostics and wearable health monitoring.

Improving Anti-Corrosion Property of Aluminium Alloy by Fabrication MAO Coating via Mixing Titanium Potassium Oxalate into Electrolyte.

Titanium potassium oxalate had been mixed into the electrolyte to improve the anti-corrosion property of the micro arc oxidation coating on the surface of the aluminium alloy. The surface and cross-section of the coating at different titanium potassium oxalate concentrations had been observed by scanning electron microscopy, showing that when the titanium potassium oxalate concentration was 10 g/L, the coating compactness was better. Additionally, the element content of the coating had been studied by the energy dispersive spectrometer, and results proved that the coating consisted of Al, O, Ti, Si, and P. The Ti increased with the increase in titanium potassium oxalate concentration. The X-ray diffractometer had been employed to analyze the crystalline structure of the coating. Then, it was found that after the micro arc oxidation, an alumina oxide coating was prepared on the surface of the aluminium alloy, and the Al2O3 and TiO2 characteristic peak was observed. Furthermore, the electrochemical workstation was used to test the anti-corrosion of the coating. It was proved that when the titanium potassium oxalate concentration was 10 g/L, the open circuit voltage, corrosion current, corrosion potential, and impedance of the coating were improved, and the anti-corrosion property of the aluminium alloy had been strengthened.

Investigation of Response Characteristics and Reaction Mechanisms in Nanonickel Doped Sodium Alginate/Graphene Oxide Artificial Muscles.

To address the shortcomings of traditional actuators, such as large size, high energy consumption, and slow response, this study developed a conductive and responsive artificial muscle, exploring the operational principles and performance enhancement techniques for artificial muscles made from sodium alginate and graphene oxide. Initially, the research outlined a preparation methodology using sodium alginate, graphene oxide, and nanonickel as primary materials. Subsequent adjustments in the nanonickel content optimized critical performance metrics, including output force, lifespan, and deflection displacement. Furthermore, the electrochemical properties of the artificial muscle were methodically assessed by utilizing an electrochemical workstation. Comprehensive examinations of surface and internal microstructures, as well as reaction mechanisms, were conducted through scanning electron microscopy and X-ray diffraction analysis. The findings demonstrated that nanonickel supplementation markedly improved the responsiveness and electrochemical properties of the artificial muscle under electrical stimulation, underscoring its substantial promise in biohydrogels and biomimetic technology applications.

PRODUCTION OF HIGH-PERFORMANCE SUPERCAPACITOR ELECTRODES BASED ON GRAPHENE-LIKE CARBON OBTAINED FROM TEA WASTE

This article presents the results of a study on the production of active material for supercapacitor electrodes from graphene-like carbon obtained from tea waste, carbonization at a temperature of 550°C, followed by thermochemical activation using potassium hydroxide in a ratio of 1:4 at a temperature of 850°C in a quartz tube furnace. The structure and morphology of the resulting porous graphene-like carbon based on tea waste were investigated using scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), X-ray diffraction, and Raman spectroscopy. The surface area of activated porous graphene-like carbon from tea waste was 2407 m2/g. Electrochemical characterization of the assembled supercapacitor using GLC-TW was performed on an Elins P-40X electrochemical workstation and showed high specific capacitance values of 182 F/g, as well as a Coulombic efficiency of 96% at a current density of 1 A/g and the material also demonstrated a low charge transfer resistance of about 1.5 Ohms. These results highlight the effectiveness of using graphene-like carbon derived from tea waste, demonstrating its potential as a promising material for supercapacitors.

Microstructure and Corrosion Resistance of Laser-Cladded FeCo1.5CrNi1.5Ti0.5 High-Entropy Alloy Coatings

Due to their excellent mechanical properties and corrosion resistance, high-entropy alloys (HEAs) have the potential to be used as new engineering structures and functional materials. In this study, an FeCo1.5CrNi1.5Ti0.5HEA coating was prepared on the surface of a 1Cr18Ni9Ti alloy by laser cladding technology. Phase structure and microstructure were characterized by XRD and using an SEM. The corrosion resistance was evaluated by an electrochemical workstation, and the polarization curves were obtained in simulated seawater and 3.5 wt.% NaCl and 5% HCl solutions. The corrosion morphology of the Fe-based HEA coating was further characterized using the SEM, super depth of field observation, and 3D topological images. The results showed that the Fe-based HEA coating had a single-phase FCC structure with a grain size of about 10.7 ± 0.25 μM. Electrochemical analysis results showed that the corrosion resistance of the current Fe-based HEA coating was poor in HCl solutions. However, it exhibited good corrosion properties in simulated seawater and 3.5 wt.% NaCl solutions. Further analysis of the corrosion morphology revealed that in simulated seawater and the 3.5 wt.% NaCl solution, the surface of the current Fe-based HEA coating exhibited a preferential corrosion tendency between dendrites, while in the 5% HCl solution, it exhibited more obvious pitting characteristics. The results indicate that the current Fe-based HEA coating exhibits good comprehensive performance, especially in an acidic Cl− corrosion environment. These findings provide a reference for the application of laser cladding prepared Fe HEA coatings.

One‐Step Hydrothermal Process to Fabricate Hydrophobic Mg–Al Layered Double Hydroxide Coating on MAO–Coated AZ31 Magnesium Alloy and Its Durability

In order to improve the corrosion resistance of micro‐arc oxidation (MAO) ceramic layer of AZ31 magnesium alloy, a hydrophobic Mg–Al layered double hydroxide (LDH) coating was prepared on its surface by a one‐step hydrothermal method. The microstructure of the coating was characterized by scanning electron microscope, energy disperse spectroscopy, X‐ray diffractometer, and Fourier transform infrared spectrometer. The wettability and corrosion resistance of the coating were studied by contact angle (CA) measuring instrument and electrochemical workstation. Meanwhile, the durability of the coating was evaluated by sandpaper abrasion, tape peeling and immersion test. The results showed that the hydrophobic Mg–Al LDH coating can be successfully prepared on the surface of MAO ceramic layer by one‐step hydrothermal treatment with alkaline aluminum nitrate solution containing sodium laurate. The hydrophobic Mg–Al LDH coating sealed the inherent defects of MAO ceramic coating, resulting in significantly improved corrosion resistance. With the extension of sandpaper abrasion distance, tape peeling times, and immersion time, the CA of the coating shows a downward trend, and the coating gradually changed from hydrophobic to hydrophilic. However, after the durability test, the coating still has good corrosion resistance, and its corrosion current density was still lower than that of MAO ceramic layer.

A Simple Surface Treatment for Improving the Adhesive Bonding Properties and Durability of an AlMg3 Alloy.

The structural adhesive bonding of aluminum is widely used in the aircraft and automotive industries. The surface preparation of aluminum prior to adhesive bonding plays a significant role in improving the bonding strength. Surface cleanliness, surface roughness, and surface chemistry can be controlled, primarily, by proper surface treatment methods. In this study, the effect of varying the chemical treatment period on the adhesive bonding characteristics was investigated. An epoxy adhesive was used to join the treated surfaces, and the bond strengths were evaluated via single lap-shear (SLS) tests in pristine, as well as degraded, conditions. The surface morphology, chemistry, and corrosion properties of the surfaces with chemical treatments were characterized using various surface analytical tools, such as scanning electron microscopy, an energy dispersive spectrometer (SEM/EDX), and an electrochemical workstation. Excellent adhesion characteristics, with the complete cohesive failure of the adhesive, were encountered on the surfaces of the H2O2-treated samples. The H2O2-treated samples exhibited the highest initial bond strength, reaching 22.5 ± 0.5 MPa, and showed a decrease of only 10% (to 18.1 ± 0.2 MPa) after aging under extreme humidity and temperature conditions (70 °C and 100% R.H. for 4 weeks). The chemical treatment reported in this work is a very simple method to produce durable joints.

DNA Reaction Network Central Controller for Dynamic Spatiotemporal Logical Assembly and Its Application for Rational Design of Fluorometric/Electrical Biosensing.

This work introduces a fluorometric/electrical dual-biosensing logic system based on a DNA reaction network (DRN). This system was used to spatiotemporally modulate the kinetic behavior of DNA nanostructures. The system, acting as a programmable and modulative central controller introduced to implement, enabled the monitoring of the target gliotoxin. The DRN encompasses multiple pathways and provides a potential mechanistic way to develop dynamic networks that can evolve under directional controllable conditions. We demonstrated the implementation of a DRN to control the assembly and disassembly of a DNA conveyor belt. By exposing the responsive switches of the DNA conveyor belt, the DRN activates the operation of fluorescent DNA-driving axes based on the aggregation-induced emission effect, enabling signal generation and collection through continuous rolling on the surface of the DNA conveyor belt. The biosensor was employed to monitor gliotoxin, and under optimal conditions, dual-signal detection was achieved at 1.14 × 10-7 and 2.45 × 10-7 μg·mL-1. The biosensor was integrated with a handheld electrochemical workstation, which enabled the successful monitoring of gliotoxin. This strategy enables self-tuning control and the multilayer hierarchical assembly of kinetic behaviors and is applicable to diverse fields such as biometric systems, medical diagnosis, and logic computing.

Analysis of a fitting model based on polarization characteristics of solid oxide fuel cells

Reliability and long life are the keys to the large-scale commercialization of solid oxide fuel cells (SOFCs), so many studies have focused on how to diagnose SOFC degradation mechanisms. Electrochemical tests have been widely used to study SOFC degradation. The SOFC overpotential can be obtained by measuring the current-voltage (I–V) curves, but these measurements do not show the cause of the SOFC performance attenuation. Electrochemical impedance spectroscopy (EIS) measurements can measure various types of SOFC impedances, but this method is difficult to apply to the high-power stack due to the limited output power of the electrochemical workstation. This paper presents a resistance fitting model based on the I-V measurements for large SOFCs that can determine various electrochemical parameters and resistances by fitting the voltages for different regions of the current densities. The model accuracy is verified by EIS measurements at various current densities with the mean absolute percentage error for each type of resistance given by the fitting model being within 10 % of the EIS measurements which shows that the model can accurately identify the SOFC degradation mechanisms.

Preparation and properties of Ni-SiO2 superhydrophobic coating by brush plating on inner wall of pipeline

Coal is easy to stay on the inner wall of the pipeline during transportation. In order to solve this problem, it is usually necessary to improve the hydrophobicity of the inner wall of the pipeline. In this study, 45 # steel, which is wear-resistant and has good machinability, is used as the matrix for coal pipeline. Ni-SiO2 composite coatings were prepared on the inner surface of 45 # steel pipelines using a novel brush plating tool, and the hydrophobicity of the coatings were evaluated. Firstly, a series of four-factor and three-level orthogonal tests were conducted to investigate the impact of brush plating working voltage (12V, 14V, 16V), nanoparticle concentration (1g/L, 2g/L, 3g/L), brush plating duration (2min, 3.5min, 5min), and bath temperature (25 ℃, 35 ℃, 45 ℃) on the hydrophobicity of the composite coating. Subsequently, optimum process parameters were determined. Then 1H, 1H, 2H, 2H- perfluorodecyltrimethoxysilane was used to modify the coating surface in order to further improve its hydrophobicity. Scanning electron microscope (SEM), energy spectrum analyzer (EDS), optical contact angle measuring instrument, white light interferometer, Vickers hardness tester, scratch tester, friction and wear meter and electrochemical workstation were used to evaluate the coating's related properties. The experimental results show that the Ni-SiO2 nano-composite coating has a higher angle (135°) when the operational voltage of brush plating is 14V, the amount of nanoparticles is 3g/L, the brush plating time is 2min, and the bath temperature is 35 ℃. The concentration of nanoparticles is the biggest factor affecting the hydrophobicity through orthogonal test analysis, so the control variable method is used to further study the influence of the concentration of nanoparticles on the comprehensive performance of the coating. It was found that with the increase of nanoparticle concentration, surface quality and comprehensive performance of the coating showed a trend of increasing first and then decreasing, and the surface of the coating was rougher when the nanoparticles were added at 4g/L, and the maximum porosity was 31.34%. At this time, the contact angle of the super hydrophobic coating has reached 150.1°, which has reached the super hydrophobicity, and the coating has good hardness, wear resistance and corrosion resistance.

Study on the dissolving performance of the Mg-(5, 8, 10wt.%)Sn-1.5wt.%Al alloys

Abstract A metallographic microscope and a scanning microscope were used to observe the extruded and corroded microstructure of the Mg-(5, 8, 10wt.%)Sn-1.5wt.%Al alloys. An electrochemical workstation was used to test the electrochemical performance of these samples. It shows that the Mg-Sn-Al alloys have good plasticity and dissolving properties after extrusion. Among them, the Mg-8wt.%Sn-1.5 wt.%Al alloy has the best plasticity, which is 22.5%. At the same time, it has the best-dissolving properties, with a double-layer capacitance in a solution of 9.448*10−6 F·cm−2. The dissolution process in the 3% kcl solution is a uniform intergranular corrosion.

Evaluation of Ni-Co/TiO2-CeO2 nanocomposite coatings fabricated by electro-co-deposition

Multiarticulate metal matrix composites have recently attracted the attention of many researchers. In this study, the efficacy of two reinforcement particles, TiO2 and CeO2, on the Ni-Co alloy coating was investigated. This coating is formed via the electro-co-deposition method on the copper substrate. The coated copper was examined and identified using field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) system, an electrochemical workstation, surface roughness measuring instruments, and a microhardness machine. Findings showed that adding TiO2 and CeO2 nanoparticles into Ni-Co makes better the morphology of the surface, decreases the crystalline size, and improves the corrosion resistance, wear resistance and microhardness of the Ni-Co alloy coating. For Ni-Co /TiO2-CeO2 coating, the average surface roughness value was estimated at 85 nm, which is almost twice the roughness of Ni-Co alloy coating.

Linear NiCo2O4 modified by CuO nanoparticles with wide range and high sensitivity for glucose detection and excellent ultracapacitor performance

To develop materials that can meet the sensing and capacitive performance of glucose. Hydrothermal and electroplating procedures were used to prepare linear NiCo2O4 and nano-CuO particles, respectively. The sensor's sensitivity was 1174.57 μA mM-1 cm-1, with a low detection limit of 0.024 μM (S/N=3), and its detection range was 0.3-12.6 mM, with good stability as verified using an electrochemical workstation. In addition, at a current density of 2 A g-1, this material exhibits a specific capacitance of up to 2140.0F g-1 in supercapacitors. After 5000 cycles, its stability remained at 93.89%. Similarly, asymmetric supercapacitor devices based on nickel foam exhibit A high specific capacitance of 605.5 F g-1 at a current density of 2 A g-1. It is demonstrated that linear NiCo2O4 modified with CuO nanoparticles can be employed not only as a sensitive material for glucose sensors but also for the production of supercapacitors.

Performance of xMg3Al1-LDH@ZIF-8 in High Efficiency Electrocatalytic Reduction of CO2 to CO.

This study involves the preparation of the precursor of magnesium aluminum layered double hydroxide (Mg3Al1-LDH) through a hydrothermal synthesis method. Subsequently, altering the loading amount of the precursor to synthesize a series of nanomaterials (xMg3Al1-LDH@ZIF-8, x = 0.2, 0.5, and 0.8) composite with zeolitic imidazolate framework-8 (ZIF-8). The investigation delves into the electrocatalytic performance of the material in the electrochemical reduction of CO2 (CO2RR) for the production of CO. The electrocatalyst is subjected to analysis through various techniques such as XRD, XPS, Raman, FTIR, SEM, EDS, TEM, BET, etc., to examine the elemental composition, microscopic morphology, and surface area with pore size. The electrochemical performance of the materials is tested and analyzed using an electrochemical workstation and gas chromatograph. The research findings reveal that the electrocatalyst with a loading amount of 0.5 g, denoted as 0.5Mg3Al1-LDH@ZIF-8, exhibits a well-defined rhombic dodecahedral morphology with a surface-attached layered structure. This structure, characterized by relatively strong interactions, provides abundant active sites for the reaction, consequently demonstrating superior electrochemical performance. The Faradaic efficiency (CO FE) for CO2RR to produce CO reaches a maximum of 88.08% at -1.5 V vs. RHE. Maintaining a constant applied voltage at -1.4 V vs. RHE ensures stability for up to 4 h.

(Invited) Elucidation of Degradation Mechanisms of Ni Cermet Electrode during Co-Electrolysis Using Cross-Section Model Electrodes

One of the main problems in the commercialization of solid oxide H2O/CO2 co-electrolysis cells is performance degradation during long-term operation which mainly comes from the nickel migration and carbon deposition in the fuel electrode. In order to suppress the degradation, it is essential to understand its mechanism. However, practical porous cermet electrodes have a complex three-dimensional structure, making it difficult to separate the multiple causes of degradation. Therefore, a model electrode is used to understand the degradation phenomena. While previous studies used glid pattern electrodes [1], we use comb-shaped model electrodes. We developed a comb-shaped Ni electrode on the YSZ thin film that simulate a porous Ni/YSZ into a flat surface [2]. The comb model electrode has a structure in which anode and cathode thin-film electrodes are formed on a YSZ thin-film in the form of a comb. It allows the mechanism of Ni migration and carbon deposition to be revealed in the cross-sectional direction. To further understand the degradation mechanism, the morphological change of the electrode was captured in real-time by operando evaluation using a comb-shaped model cell to evaluate the distribution of migrated nickel and deposited carbon.The model electrode was fabricated by sputtering YSZ thin film on single-crystal MgO, on which thin-film patterned electrodes of Ni and Pt were fabricated by photolithography. Ni acts as WE (working electrode) and Pt as CE (counter electrode), WE and CE are 40 mm apart. To eliminate the contribution of the counter electrode, the Pt reference electrode was deposited in the middle of the YSZ electrolyte. The measurements were done under two different conditions: 1. Water electrolysis and 2. Co-electrolysis. The measurement was carried out at 1073 K with 10% H2O + 1% H2 + 99% Ar for water electrolysis and 10% H2O + 10% H2 + 20% CO2 + 70% Ar for co-electrolysis. The long-term measurements were performed for 100 h at -0.462 V from RE (reference electrode) to WE in water electrolysis, -0.516 V from RE to WE in co-electrolysis where the impedance measurements were taken for every 5 h by electrochemical workstation (Biologic SP-300). During the measurement, a laser microscope (Keyence VK-X3000, Japan) recorded the microstructure change for 100 h.In both steam electrolysis and co-electrolysis, the tip of the Ni electrode was raised by electrolysis, suggesting that Ni was exfoliated from the YSZ by the electrolysis of water vapor and carbon dioxide. In the co-electrolysis, carbon deposition was observed at the tip of the Ni electrode by EDX and EPMA results. This carbon deposition is concentrated at the tip of the comb, suggesting that the electrode reaction is concentrated at the interface between the fuel electrode and the electrolyte. The calculated reaction area length obtained from the transmission line model (TLM) was close to the range where the electrode was delaminated and carbon deposition was observed, suggesting that more quantitative analysis would allow the comb model electrode to reveal the conditions under which degradation phenomena occur. Acknowledgement This study was supported by the New Energy and Industrial Technology Development Organization (NEDO), Japan, grant number JPNP16002.

Determination of Oxygen Reduction Reaction Process of La0.6Sr0.4CoO3- δ Porous Electrode Using Nonlinear Frequency Response Analysis

Electrochemical impedance spectroscopy (EIS) is a method to measure the performance of an electrochemical cell where linear responses are obtained when a small perturbation of current or voltage is applied to the cell. It is so often that different limiting steps of electrochemical processes give similar responses of the impedance spectrum. Therefore, the typical linear EIS measurements are not sufficient to understand the electrode reaction mechanism. On the other side, the frequency response analysis including nonlinearities can provide more information in addition to EIS, and is considered an advanced method to understand the reaction mechanism as reported by the research group of S. Adler [1,2]. In EIS, the small perturbation is applied to the cell so that the input and output can be regarded as a linear relationship. Meanwhile, in the non-linear electrochemical impedance spectroscopy (NLEIS) large perturbation is applied to the cell. In this way, NLEIS can visualize not only the fundamental waveform but also the changes in the harmonics, which is expected to enable more detailed analysis and reaction modeling. Using the above principles in potentiostatic mode, this study aims to elucidate the ORR process of La0.6Sr0.4CoO3- δ (LSC) porous electrode for SOFC cathode.A symmetrical cell was prepared by depositing LSC porous electrodes on both sides of a Gd0.1Ce0.9O1.95 electrolyte. The experiments were performed in I-V measurements and NLEIS as a function of temperature (873 – 1073 K) under various p(O2) (1 – 10-4 bar). An electrochemical workstation (Zahner Zennium, Zahner-Elektrik GmbH & Co. KG, Germany) was used for the measurement to obtain the non-linear response. The obtained harmonics are normalized by the amplitude of the fundamental wave after Fourier transformation, and data are output up to the fifth harmonic. NLEIS was performed at frequencies from 0.1 Hz to 1M Hz.The experimental results showed clear response at the second harmonic with the magnitude increasing and phase changing as the frequency decreased. Harmonic components tended to increase with decreasing p(O2) and increasing temperature. In addition to experiments, the simulation using an electric circuit simulator (LTspice, Analog Devices) was performed. As an equivalent circuit of a mixed-conducting porous electrode, a ladder circuit has been applied to analyze the nonlinear response. The currents related to ion diffusion were defined based on the Nernstian Einstein equation, and the currents related to surface reactions were defined based on an empirical model of oxygen adsorption and dissociation[3]. The result showed that the 1st harmonic and 2nd harmonic responses from the experimental result is in good agreement with the simulation results from LTspice at high p(O2) (1 – 10-2 bar) in the terms of the shape and phase of the response. At low p(O2) (10-3 – 10-4 bar), the effect of gas diffusion resistance could not be ignored.. The complete analysis on ORR process as a function of the p(O2) and temperature will be discussed after resolving technical issues related to computational convergence when gas diffusion resistance is included into the equivalent circuit.

Nickel foam supported CuO/Co3O4/r-GO is used as electrode material for non-enzymatic glucose sensors and high performance supercapacitors

In order to solve the problem of glucose detection in medical development and meet the urgent demand for new energy storage devices, this paper proposes a new material suitable for glucose sensing and capacitive properties. The sensor was fabricated by depositing Co3O4 nanoparticles onto nickel foam with integrated r-GO via the hydrothermal method, followed by the synthesis of CuO nanoparticles using electroplating. The detection range of the sensor is 0.3–11.3 mM. The sensor's sensitivity is 1000.3 μA mM−1 cm−2, indicating its responsiveness to changes in analyte concentration. In electrochemical test systems, Signal-to-Noise Ratio (SNR) usually represents the relative intensity of the effective current signal and the background noise, reflecting the accuracy and reliability of the measurement. When the SNR is three, the minimum detection limit is 0.431 μM, highlighting its ability to reliably detect analytes at low concentrations amidst background noise. According to electrochemical workstation tests, the sensor demonstrates robust stability. Furthermore, the electrode material proves suitable for asymmetric supercapacitor devices, when the current density is 2 Ag−1, the specific capacitance is 660.5 Fg−1. At the same time, we also explore the cyclic stability of the device, which can retain 92.3 % of its initial specific capacitance after 5000 cycles, showing its remarkable long-term stability. In addition, the prepared nanocomposites can also light the red LED light. The results show that the synthesized CuO/Co3O4/r-GO/NF electrode can be used for electrochemical glucose sensing and supercapacitors, and plays an important role as a multi-functional material in the fields of medical, food, electronics, transportation and energy, providing key technical support for a variety of applications.

A reliable, practical and cost-effective portable wireless potentiostat for mobile chemical sensing and biosensing

Abstract Traditional electrochemical workstations are costly, complex, bulky, and primarily used in laboratories. This study develops a reliable, practical, and cost-effective portable wireless potentiostat to achieve real-time detection on-site and overcome the limitations of traditional electrochemical workstations. The system employs a general-purpose microcontroller unit (MCU), a dual-mode Bluetooth module and cost-effective multi-analog-to-digital converter (multi-ADC) to achieve differential sampling of the LMP91000. The system is equipped with buttons and OLEDs, enabling connection to mobile phones and computers for in-depth data analysis or independent operation. The system was successfully tested with [Fe(CN)6]3-, C6H12O6, and C3H6O3 solutions at concentrations ranging from 0 to 20 mM. The goodness-of-fit (R²) values are 0.984, 0.996, and 0.998, respectively. The average relative standard deviation of the three blank solutions is approximately 3.22%. The detection limits measured (0.003, 0.009, and 0.005 mM) are all lower than the minimum detection concentration (0.2, 0.1, and 0.1 mM). The coefficient of variation for repetitive experiments is less than 5.53%. The device accurately executed chronoamperometry (applied voltage range is ± 1.2 V, current range is ± 882 μA, accuracy is ± 1 %) with high sensitivity and good repeatability. Based on this circuit, a lactic acid detector and a urine glucose detector were developed, which work stably and support long-term operation, proving the stability and reliability of the circuit. Compared to commercial electrochemical workstations, PWES offers remarkable advantages in cost (< $6.4), size (41.5 mm × 76.5 mm), and practicality, making it suitable for a range of applications, including biomedical analysis, food safety, environmental monitoring, and smart wearables.