Charge Transfer Coefficient Research Articles

Electro-sensing base for hazardous pesticide 2, 4-DCP and its quantification in real samples at ZnO@Cu core-shell nanoparticles in the presence of cationic surfactant

We developed a novel sensor using carbon paste electrode (CPE) modified with cationic surfactant cetyltrimethylammonium bromide (CTAB) and the core-shell nanoparticles (NPs) of zinc oxide at copper (ZnO@Cu) to study an electrochemical behavior of 2, 4 - dichlorophenol (2, 4 - DCP), a harmful molecule. The core-shell ZnO@Cu NPs/CTAB/CPE is proved to be sensitive because of its sensing features for 2, 4-DCP. The sensor showed excellent electro-catalytic behavior and elevation in peak current in the presence of phosphate buffer solution (PBS) of 0.2 M strength. Advanced techniques like transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDS), and scanning electron microscope (SEM) were employed to ZnO@Cu core-shell NPs characterization. The cyclic voltammetry (CV), as well as square wave voltammetry (SWV) techniques, were applied to study electro-kinetic parameters, including specific heterogeneous rate constant, charge transfer coefficient, accumulation time, scan rate, the effect of temperature, pH, the energy of activation, enthalpy, entropy, Gibb's free energy, and the number of electrons transferred in the 2, 4 - DCP electro-oxidation. By SWV technique, the 2, 4 - DCP molecule was analyzed in vegetables, fruits, water, and soil samples.

Elimination voltammetry as an innovative tool of electroanalysis

• Overview of principles and applications of elimination voltammetry with linear scan (EVLS). • EVLS as a promising tool for obtaining new information about electrochemical processes. • A critical look on the use of EVLS for LSV or CV experiments. • Perspectives and possibilities of EVLS for description of different electrode process mechanisms (CE, CEE). The review presents the application potential of elimination voltammetry with linear scan (EVLS) in the electroanalysis of organic and inorganic electroactive substances. This innovative method can be considered a software tool that transforms the total current-voltage records measured at different scan rates into elimination functions providing new useful information about a given electrode process. Some EVLS functions are capable of separating overlapped voltammetric signals, identifying the adsorbed state of the analyte, and detecting the preceding chemical reaction before the electron transfer. EVLS finds use in solving the mechanisms of electrode processes and determining significant physicochemical parameters, such as charge transfer coefficients and electrochemical equilibrium protonation constants. This review selects and draws attention to certain problems that may accompany EVLS in voltammetric experiments on solid electrodes.

Synthesis and characterization of graphene nanosheets for electrochemical quantification of chlorpheniramine maleate drugs using a modified glassy carbon electrode

The development of innovative sensors for the detection of analytes at extremely low concentrations with great sensitivity and selectivity has been a major focus of this study. The electrochemical activity of chlorpheniramine maleate (CPRM) in the presence of a graphene modified GCE has been investigated. Cyclic voltammograms (CV) have been obtained in the linear dynamic range 3.5- 156 μM while the optimum pH range and the maximum peak current (IPa) have been measured at pH 7.3. The process on the electrode's surface, diffusion regulated, heterogeneous rate constant, charge transfer coefficient, and the number of electrons transferred among the physicochemical properties have been obtained. Differential pulse voltammetry (DPV) of CPRM at the modified has electrode revealed a good linear calibration curve with a linear range of 10 to 60 μM and limit of detection of 0.062 μM. The suggested sensor has been fabricated and utilized to determine CPRM in medicines as well as serum samples.

Determination of Kinetic Parameters for the Oxygen Reduction Reaction on Platinum in an AEMFC

To promote the development of anion exchange membrane fuel cells (AEMFC), an understanding of the oxygen reduction reaction (ORR) kinetics in porous gas diffusion electrodes is essential. In this work, experimental polarisation curves for electrodes with different platinum catalyst loadings and oxygen partial pressures at the cathode are fitted to a physics-based porous electrode model in the voltage range from open circuit voltage (OCV) to 0.7 V. Polarisation curves measured with different anode catalyst loadings, and hydrogen partial pressures, were used to verify the model. The reactions are described using a two-step Tafel-Volmer pathway at the anode and concentration-dependent Butler-Volmer kinetics at the cathode. A good fit to experimental data in the kinetic region is obtained with an exchange current density of a first order dependency on oxygen partial pressure, and a charge transfer coefficient of 0.8 for the ORR. For lower oxygen partial pressure, hydrogen crossover is needed to explain the downward shift of the polarisation curves in the kinetic region. In the experimental data, the polarisation curves show an apparent limiting current density at lower hydrogen partial pressures, explained by the lower rate of the Tafel step at these conditions.

Enhanced Performance of Bioelectrodes Made with Amination-Modified Glucose Oxidase Immobilized on Carboxyl-Functionalized Ordered Mesoporous Carbon.

This research reveals the improved performance of bioelectrodes made with amination-modified glucose oxidase (GOx-NH2) and carboxyl-functionalized mesoporous carbon (OMC-COOH). Results showed that when applied with 10 mM EDC amination, the functional groups of NH2 were successfully added to GOx, according to the analysis of 1H-NMR, elemental composition, and FTIR spectra. Moreover, after the aminated modification, increased enzyme immobilization (124.01 ± 1.49 mg GOx-NH2/g OMC-COOH; 2.77-fold increase) and enzyme activity (1.17-fold increase) were achieved, compared with those of non-modified GOx. Electrochemical analysis showed that aminated modification enhanced the peak current intensity of Nafion/GOx-NH2/OMC-COOH (1.32-fold increase), with increases in the charge transfer coefficient α (0.54), the apparent electron transfer rate constant ks (2.54 s−1), and the surface coverage Γ (2.91 × 10−9 mol·cm−2). Results showed that GOx-NH2/OMC-COOH exhibited impressive electro-activity and a favorable anodic reaction.

Modelling of self-sustainable microbial fuel cell type oil sensors based on restricted oxygen transfer and two-population competition

Oil leaks during oil industrial chain pose threats to the ecosystem. The microbial fuel cell-type oil sensor has been developed for early warning of such issues. Oil contacting with the sensor restricts oxygen availability and triggers correlative signal anomaly which serves as indicative of the oil presence. To extend its application for the real world, modelling of the sensor is required to pre-describe the signal behavior under unknown conditions. Therefore, by integrating Butler-Volmer, restricted oxygen transfer (ROT) and Monod equations, a dynamic ROT-MFC model with sufficient substrate precondition was developed. The ROT-MFC model was trained on the experimental single-oil-shock test (R 2 = 0.996) and validated by the experimental sequential-shocktest (R 2 = 0.998). Numerical analysis of the trained ROT-MFC model indicates that the single-shock detection has higher sensitivity (≥40.6 mV/detection) and the sequential-shocks detection spends a shorter response time (≤2.2 h). Besides, the sequential-shocks detection with proper strategy is more applicable due to flexible options on detection limit and working range. The model was further evolved into the TPC-ROT-MFC model by introducing a two-population competition (TPC) theory to describe performance under limited substrate conditions. Results indicate a critical substrate concentration range (42.1 to 62.8 mg-COD/L) for dividing baseline steadiness, and that the impact of substrate concentration on anodic charge transfer coefficient soars when the substrate concentration lessens furtherly. This sensor model is relatively easy to implement and may enhance practical use for design and operation.

A potential and pH inclusive microkinetic model for hydrogen reactions on Pt surface

The Pt surface-based hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) are the two most basic electrochemical reactions. However, an accurate quantitative microkinetic model of HER and HOR on Pt surface is still missing. In the current work, the charge transfer coefficient and potential-dependent reaction barriers are obtained via grand canonical fixed-potential calculations to predict such polarization curves. Excellent agreements between the prediction and experiments have been obtained. We found that the common practice of relating a Tafel slope to one specific prominent reaction channel is not reliable. Instead, the balance of several pathways might determine the Tafel slope. Our work demonstrated the important roles of the fixed-potential approach, the explicit water layer structure, and the cations in predicting the Pt-HER/HOR accurately. The proposed computational framework can be generally applied to other electrochemical processes.

Kinetics of V5+/V4+ Redox Reaction—Butler-Volmer and Marcus Models

Kinetics of the V5+/V4+ redox reaction on Vulcan XC-72 modified glassy carbon disk electrode is investigated in a three-electrode configuration. Cyclic voltammograms of V5+/V4+ redox couple suggest that the overpotential range for the kinetic analysis is limited to ±300 mV, after excluding V4+/V3+ redox reaction at the negative overpotential and the oxygen evolution reaction at the positive overpotential. The linear sweep-voltammograms (LSVs) are corrected for potential drop due to solution resistance (iR s ), mass-transfer resistance, and most importantly, for the back reaction current. These corrections are imperative to estimate the Tafel slope in the limited range of overpotential for V5+/V4+ redox reaction. The charge-transfer coefficient (α) estimated from the Tafel slope deviates significantly from the expected value of 0.5 for the single electron-transfer reaction. Moreover, the instantaneous slope of the Tafel plot suggests that the α is overpotential dependent. Therefore, Marcus theory of electrochemical kinetics is applied to estimate the α. The reorganization energy (λ) calculated from the Arrhenius plots is in the range of values reported in the literature for the other redox couples.

Void fraction in vertical intermediate and inlet headers of microchannel heat exchangers: Experiments and models

The void fraction in headers of microchannel heat exchangers (MCHEs) affects the refrigerant charge, distribution, pressure drop, and heat transfer coefficient of MCHEs. However, due to the complex geometries of headers, experimental measurements of void fraction in headers with refrigerant are still missing in the open literature. A model that predicts local void fraction between microchannel tubes in headers is also widely needed when predicting the refrigerant charge and the performance of MCHEs. This paper first presents experimentally measured void fraction between microchannel tubes in a intermediate (five inlets and five outlets) and inlet headers (ten or five outlets) with R134a by calibrated capacitive sensors. For the intermediate header, the ranges of inlet mass flow rate and quality are 3.2 g s−1 to 5.2 g s−1 and 0.2 to 0.8, respectively. The inlet mass flow rates vary from 3.2 g s−1 to 7.2 g s−1 and qualities range from 0.1 to 0.82 for the inlet headers. As the inlet quality increases, the average void fraction in headers becomes larger. Other local parameters in the headers, such as mass flux, quality, superficial velocity together with the visualization results are also obtained. Void fraction shows a strong relation to the local quality in headers and the refrigerant distribution in microchannel tubes. A drift-flux void fraction model based on the local variables is proposed in this paper. The local void fraction predicted by the model agrees well with the experimentally measured values, with most of the predictions falling into ± 15% deviations. The proposed model has better accuracy when predicting void fraction in headers comparing to some widely used correlations.

Spectroscopic and Electrochemical Investigation of Adsorbed Nitroxide Radicals

Deep eutectic solvents (DESs) have gained interest as electrolytes for grid-scale energy storage applications such as flow batteries. Here, we report on processes that govern the charge-transfer kinetics involving a redox-active organic (4-hydroxy-TEMPO, HT) species in chloride containing aqueous and DES electrolytes. Using polarization measurements, we show that the apparent anodic charge transfer coefficient α for a one–electron oxidation of HT approaches 1.1 This is a significant deviation from the expected value of α ≈ 0.5 for a symmetric one–electron transfer reaction involving a soluble – soluble redox transition. To explain this unusual value of α, a two–step adsorption – desorption mechanism is proposed, wherein HT undergoes fast charge transfer and adsorption at the electrode surface, followed by slow desorption of the adsorbed oxoammonium cation. Evidence collected using in situ surface enhanced Raman spectroscopy, combined with density functional theory simulations, suggests the presence of the adsorbed oxoammonium on the electrode surface. Additional evidence of adsorption, collected using a novel electrochemical approach, is presented.[1] N. A. Shaheen, M. Ijjada, M. B. Vukmirovic, and R. Akolkar, J. Electrochem. Soc., 167, 143505 (2020).

The prediction of the polarization curves of a solid oxide fuel cell anode with an artificial neural network supported numerical simulation

The presented study focuses on a numerical simulation of the transport phenomena inside a solid oxide fuel cell anode. The classical mathematical model leads to a notable discrepancy between measured and predicted overpotentials. One of the possible reasons is the assumption of the constant values of electrochemical reaction charge transfer coefficients. A modified formulation of the problem includes data-driven correction of reaction charge transfer coefficients in the electrochemical reaction model. Here we show a dedicated computational scheme in which an artificial neural network updates the charge transfer coefficients depending on the operational conditions and the available datasets. The neural network was trained on twelve experimental data points of an anode's polarization curve obtained from the literature. The training set contained data for the anode operating in two different temperatures - 800 °C and 900 °C. The test set contained additional six data points for an anode operating at 1000 °C. Charge transfer coefficients were proposed by the Artificial Neural Network as a functional relation of the temperature and withdrawn current. The results of the predictions are juxtaposed with the experimental data from the literature. It was shown that an Artificial Neural Network could improve an electrochemical reaction model in Solid Oxide Fuel Cell modeling.

Insight into the Influence of Analyte Molecular Structure Targeted on MoS2-GO-Coated Electrochemical Nanosensors.

MoS2-GO composites were fabricated by an ultrasonication method at room temperature. Raman spectra, emission scanning electron microscopy (SEM), and transmission electron microscopy (TEM) images were used to study the structural characteristics, morphologies, and sizes of the synthesized materials. An MoS2-GO/SPE (screen-printed electrode) was prepared by a facile dropping method and acted as an effective electrochemical sensor toward clenbuterol (CLB) and 4-nitrophenol (4-NP) detection. Based on the obtained results, the influence of analyte molecular structure on the adsorption ability and electronic interoperability between the targeted analyte and electrode surface were investigated in detail and discussed as well, through some electrochemical kinetic parameters (electron/proton-transfer number, electron transfer rate constant (ks), charge transfer coefficient, and adsorption capacity (Γ)). In particular, it should be stressed that 4-NP molecules possess a simple molecular structure with many positive effects (electronic, conjugation, and small steric effects) and flexible functional groups, resulting in fast electron transport/charge diffusion and effective adsorption process as well as strong interactions with the electrode surface. Therefore, 4-NP molecules have been facilitated better in electrochemical reactions at the electrode surface and electrode-electrolyte interfaces, leading to improved current response and electrochemical sensing performance, compared with those of CLB.

Understanding non-linearity in electrochemical systems using multisine-based non-linear characterization

Background: With the development of advanced characterization techniques, lithium-ion battery non-linearities have recently gained increased attention which can benefit battery health diagnosis and ageing mechanism identification. In comparison to conventional single sine wave-based methods, the multisine-based non-linear characterization method has the advantage of capturing the dynamic voltage response within a short testing duration, and therefore has further development potential for on-board applications. However, understanding lithium-ion battery electrochemical processes that contribute to battery non-linearities is still unclear. Methods: In this paper, the sensitivity of the Doyle–Fuller–Newman model parameters are analysed in the frequency domain to investigate the electrochemical processes that contribute to the non-linear dynamics of the voltage response. To begin with, the non-linearities of the Doyle–Fuller–Newman model with validated parameters are characterized and compared to experimental data from a commercial cell. This demonstrated a significant difference between the mathematical model and the non-linearities determined experimentally. Then, a global sensitivity analysis is applied to determine the most sensitive parameter contributing to battery non-linearities. Finally, the appropriate value of the most sensitive parameter which results in the closest non-linear response to the commercial battery is estimated through minimizing the root mean square error. Results: The results show that the charge transfer coefficient is the most sensitive parameter contributing to battery non-linearities among the Doyle–Fuller–Newman model parameters. The non-linear response of the Doyle–Fuller–Newman model is validated with good agreement with the experimental results, when the Butler–Volmer kinetic is asymmetrical due to the unequal anodic and cathodic charge transfer coefficients.

Beyond the Laviron Method: A New Mathematical Treatment for Analyzing the Faradaic Current in Reversible, Quasi-Reversible, and Irreversible Cyclic Voltammetry of Adsorbed Redox Species.

A new algorithm that describes the faradaic current for elementary redox reactions in the cyclic voltammetric responses of persistently adsorbed species on metal electrodes at any scan rate is presented. This work does not assume electrochemical reversibility and instead demonstrates a set of equations that encapsulate how the forward and back charge-transfer rate constants influence the data as a function of the experimental time scale. The method presented here is compared against other approaches that rely on either finite-difference calculations or that require numerical approximation of improper integrals (i.e., ±infinity as a bound). The method here demonstrates that the current-potential data can be described by incomplete gamma functions, whose two arguments capture the relevant kinetic variables. Following the notation for the Butler-Volmer model of charge transfer, exact solutions are presented for the cases of the charge-transfer coefficient, α, equal to 1 or 0. A related algorithm based on these results affords calculation of current-potential data for 0 < α < 1, allowing comprehensive analysis (i.e., point by point) of voltammetric data throughout the reversible, quasi-reversible, and irreversible regimes. Accordingly, this work represents an alternative to the method of Laviron, i.e., analyzing just the peak splitting values, for experimentalists to understand and interpret their voltammetric data in totality.

Asymmetric behavior of solid oxide cells between fuel cell and electrolyzer operations

The electrochemical performance of solid oxide cells (SOCs) is investigated under both fuel cell and electrolyzer operations to understand their asymmetric behavior between the two operation modes. The current–voltage and electrochemical impedance characteristics of a hydrogen-electrode-supported cell are experimentally analyzed. Also, a numerical model is developed to reproduce the cell performance and to understand the internal resistances of the cell. Partial pressures of supplied gas and load current are varied to evaluate their effects on the cell performance. The gas partial pressures of hydrogen and steam supplied to the hydrogen electrode are kept equivalent so that the cell performance can be fairly compared between the two operation modes when the same current is applied. It is found that the origin of the asymmetry is mostly from the hydrogen electrode; both activation and concentration overpotentials show asymmetric behavior particularly at high current densities. A numerical experiment is also conducted by deliberately changing parameters in the model. Asymmetry in the activation overpotential is found to be originated from the non-identical charge-transfer coefficients in the Butler–Volmer equation and also from the non-uniform gas concentration formed in the hydrogen electrode under current-biased conditions. On the other hand, asymmetry in the concentration overpotential is associated with the non-equimolar counter diffusion of hydrogen and steam caused by the effect of Knudsen diffusion. Therefore, enhancing gas transport in the hydrogen electrode and reducing the contribution of Knudsen diffusion are effective approaches to reduce asymmetry not only in the concentration overpotential but also in the activation overpotential.

Template-free synthesis of ZnO/Fe3O4/Carbon magnetic nanocomposite: Nanotubes with hexagonal cross sections and their electrocatalytic property for simultaneous determination of oxymorphone and heroin

A new method is introduced to synthesize ZnO/Fe3O4/Carbon magnetic hexagonal nanotubes arrays named ZnO/Fe3O4/C MHNTA using a one-pot synthesis. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), BET surface area analysis, and energy dispersive X-ray spectroscopy (EDX) are used for the characterization of composition and morphology of Fe3O4/ZnO/C MHNTA, demonstrating its high specific surface area of the synthesized material. The synthesized nanotube possesses hexagonal cross-sections and wall thicknesses of about 25 nm, long lengths of around 1.2 µm and side lengths of about 100 nm. The mentioned properties provided rapid electron transfer and large electrochemically active surface area and assisted in the discrimination of analytes that reduce or oxidize under the same potentials. The enhanced electrode demonstrated appropriate sensing ability to oxymorphone and heroin after performing fixation of ZnO/Fe3O4/C MHNTA. Kinetic factors charge transfer coefficient, standard heterogeneous electron transfer rate constant and other different electrochemical factors are predicted using voltammetry methods. Low limits of detection (LODs), 3.5 nM and 4.7 nM, and broad liner ranges, 0.01–500.0 μM are obtained in the case of oxymorphone and heroin, respectively. In addition, the mentioned suggested a suitable potential for profiling of oxymorphone and heroin with appropriate long-term stability, repeatability and reproducibility. The excellent efficiency for the measurement of real samples demonstrated the most significant future perspectives of this sensor. In the last step, the feasible sensing approach is suggested.

Reduction of Cd(II) Ions in the Presence of Tetraethylammonium Cations. Adsorption Effect on the Electrode Process

The effect of the adsorption of tetraethylammonium (TEA) cations, which present both ionic and organic characteristics, on the reduction of Cd(II) ions have been studied from dc and ac measurements at the dropping mercury electrode. The resistance to the charge transfer (Rct) and Warburg coefficient (σ) parameters have been determined through impedance measurements. Thus, the global velocity constant has been obtained. The reduction process of Cd(II) in perchloric media is reversible and is affected by the adsorption of TEA cations, especially at high TEA concentrations. Values of E1/2, half wave potential, and DO, diffusion coefficient, obtained from both dc and ac measurements agree. The velocity constants show a decrease as TEA concentration increases, with values ranging from 0.6 to 0.01 cm·s−1. The inhibitory effect of TEA adsorption on the electrode process and the relationship between electrode coverage, θ, and velocity constants, K, using several isotherm equations, have been discussed. The best fit was obtained with the equation K = 0K(1 − θ)a with an a value close to three, indicating a blocking effect and electrostatic repulsion due to TEA.

Synthesis and characterizations of structural and electrochemical properties of CeTi2Ni4.5Al0.2Mn0.3Cr4 AB3 type compound

The structural and hydrogen absorption/desorption properties of the new AB3- type compound CeTi2Ni4.5Al0.2Mn0.3Cr4 used as material for negative electrode in Ni – MH batteries were investigated. The elaboration of the CeTi2Ni4.5Al0.2Mn0.3Cr4 was carried by mechanical alloying process starting from CeNi4.5Al0.2Mn0.3 and TiCr2 compounds. The abundance of the CeTi2Ni4.5Al0.2Mn0.3Cr4 phase increases with the milling duration and reaches its maximum of 61 wt% after 8 h and then undergoes a decrease to 40 wt% after 20 h. The electrochemical characterization shows that the discharge capacity reaches a maximum of 138 mAh g−1 and remains stable at an average value of 130 mAh g−1 after 30 cycles. The values of the hydrogen diffusion coefficient DH and the charge transfer coefficient α of CeTi2Ni4.5Al0.2Mn0.3Cr4 –based alloy show that the electrochemical reaction has good kinetics in terms of diffusibility of hydrogen. The chronoamperometry shows that the material particles act in the electrochemical reaction as clusters of 1–2 µm size.

(General Student Poster Session Winner - 1st Place) An Algorithm for Fitting Tafel Data and Determining Kinetic Parameters

Tafel analysis is widely used to characterize electrochemical kinetics and assess the properties of electrocatalysts for use in fuel cells, electrolyzers, and other applications. Conventional Tafel analysis is an extension of the Butler-Volmer equation at high overpotentials under conditions where mass transport is not significant and the reverse reaction rate is negligible compared to the studied half-reaction. Determination of kinetic parameters from a Tafel plot involves linear regression in regions of large overpotential. This method is limited in part by the subjective determination of linearity, as the kinetic parameters obtained by the regression may vary significantly depending on the chosen linear region.In an effort to increase measurement quality and decrease subjectivity, an algorithm has been developed that generates a Tafel plot from a linear sweep voltammogram (LSV) and determines the exchange current density j 0, charge transfer coefficient α, and Tafel slope of closest fit. Comparisons of kinetic parameters between conventional and algorithmic Tafel analysis are made for the hydrogen evolution reaction (HER, 2H+ + 2e- → H2) on different metal electrodes and Nafion® composite electrodes. The algorithmic Tafel analysis parameters correlate well with conventional methods. Similar agreement is observed between literature and algorithmically fitted kinetic parameters for different electrochemical systems. The developed algorithm allows for straightforward, rapid, and user bias independent Tafel analysis and can be easily used to increase measurement quality.

Electrochemical Sensor for Choline Based on Iron (III) Oxide and Functionalized Multi-Walled Carbon Nanotube at the Glassy Carbon Electrode Surface

Iron (III) oxide nanoparticle (Fe3O4NP) was synthesized via green route using Callistemon viminalis leaf extract. A composite of Fe3O4NP with functionalized multi-walled carbon nanotube (f-MWCNT) was then applied as glassy carbon electrode modifier to develop a choline sensor. Electrocatalytic oxidation of choline on nanocomposite modified electrode (GCE/f-MWCNT/Fe3O4NP) was studied by cyclic voltammetry while mechanism of electron transfer process during choline electrocatalytic oxidation was monitored by electrochemical impedance spectroscopy at fixed potential 0.5 V with frequencies between 100 kHz and 0.01 Hz. Active surface coverage area of choline, charge transfer coefficient and number of electron transferred were reported. Square wave voltammetry (SWV) was employed for the determination of choline over a linear concentration range of 24.3 - 215.6 μM. A sensitivity of 0.0244 μA/μM and 9.9 μM detection limit was found. The sensor was selective to choline (0.1 mM) in the presence of 100 mM and 0.1 mM ascorbic acid (AA) and dopamine (DA) respectively using SWV and chronoamperometry. The designed electrode was reproducible and stable. The sensor was successfully used for choline detection in choline dietary supplements with resultant good recoveries. The fabrication of the sensor was simple and cost-effective. Figure 1