scholarly journals Developing Activated Carbon Veil Electrode for Sensing Salivary Uric Acid

Biosensors ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 287
Author(s):  
Maria A. Bukharinova ◽  
Natalia Yu. Stozhko ◽  
Elizaveta A. Novakovskaya ◽  
Ekaterina I. Khamzina ◽  
Aleksey V. Tarasov ◽  
...  
Keyword(s):  
Uric Acid ◽  
Electrochemical Impedance ◽  
Linear Sweep Voltammetry ◽  
Cost Effective ◽  
Human Saliva ◽  
Charge Transfer Resistance ◽  
Oxidation Potential ◽  
Transfer Resistance ◽  
Highly Sensitive

The paper describes the development of a carbon veil-based electrode (CVE) for determining uric acid (UA) in saliva. The electrode was manufactured by lamination technology, electrochemically activated and used as a highly sensitive voltammetric sensor (CVEact). Potentiostatic polarization of the electrode at 2.0 V in H2SO4 solution resulted in a higher number of oxygen and nitrogen-containing groups on the electrode surface; lower charge transfer resistance; a 1.5 times increase in the effective surface area and a decrease in the UA oxidation potential by over 0.4 V, compared with the non-activated CVE, which was confirmed by energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, chronoamperometry and linear sweep voltammetry. The developed sensor is characterized by a low detection limit of 0.05 µM and a wide linear range (0.09–700 µM). The results suggest that the sensor has perspective applications for quick determination of UA in artificial and human saliva. RSD does not exceed 3.9%, and recovery is 96–105%. UA makes a significant contribution to the antioxidant activity (AOA) of saliva (≈60%). In addition to its high analytical characteristics, the important advantages of the proposed CVEact are the simple, scalable, and cost-effective manufacturing technology and the absence of additional complex and time-consuming modification operations.

scholarly journals Electrodeposition Kinetics of Ni/Nano-Y2O3 Composite Coatings

Metals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 669
Author(s):  
Xinyu Zhou ◽  
Yiyong Wang ◽  
Xianglin Liu ◽  
Zhipeng Liang ◽  
Hui Jin
Keyword(s):  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Composite Films ◽  
Linear Sweep Voltammetry ◽  
Electrochemical Measurement ◽  
Charge Transfer Resistance ◽  
Solid Particles ◽  
Kinetics Parameters ◽  
Transfer Resistance ◽  
Composite Deposition

Ni/nano-Y2O3 composite films were successfully prepared by electrochemical deposition using an acid sulfamate bath. The influence of solid particles added to electrolyte on electrodeposition was investigated by electrochemical measurement methods. The linear sweep voltammetry test showed that the composite deposition took place at a greater potential than that of nickel, and the presence of nano-Y2O3 decreased cathodic polarization. Chronoamperometry studies indicated that the nucleation model of both deposits similarly approached the theoretical instantaneous nucleation mode based on the Scharifker–Hills model. The Y2O3 particles adsorbed on the cathodic surface were shown to facilitate the nucleation/growth of the nickel matrix which is consistent with the deposition kinetics parameters calculated by non-linear fitting experimental curves. The results of electrochemical impedance spectroscopy showed that the presence of Y2O3 particles in a bath is beneficial for the decrease in charge transfer resistance in the deposition. The atomic force microscopy observations of both deposits obtained in the initial electrodeposition stage confirmed that the Ni-Y2O3 composite had a higher grain number and finer mean grain size.

scholarly journals Electrochemical properties and thermal stability of epoxy coatings electrodeposited on aluminium and modified aluminium surfaces

2001 ◽  
Vol 66 (11-12) ◽  
pp. 871-880 ◽  
Author(s):  
Vesna Miskovic-Stankovic ◽  
Zorica Lazarevic ◽  
Zorica Kacarevic-Popovic
Keyword(s):  
Thermal Stability ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Charge Transfer Resistance ◽  
Epoxy Coatings ◽  
Transfer Resistance ◽  
Protective Properties ◽  
Chemically Modified ◽  
Thermal Stability Of

The corrosion behaviour of epoxy coatings electrodeposited on aluminium, as well as on electrochemically and chemically modified aluminium were investigated during exposure to 3 % NaCl. Electrochemical impedance spectroscopy (EIS) and thermogravimetric analysis (TGA) were used for the determination of the protective properties of epoxy coatings on aluminium, anodized aluminium, phosphatized and chromatized-phosphatized aluminium. The protective properties of epoxy coatings on anodized and chromatized-phosphatized aluminium are significantly improved with respect to the same epoxy coatings on aluminium and phosphatized aluminium: higher values of the pore resitance and charge-transfer resistance, lower values of the coating capacitance, double-layer capacitance and relative permittivity (from EIS) smaller amount of absorbed water inside the coating (From TGA). On the other hand, the lower values of the ipdt temperature indicate a lower thermal stability of the epoxy coatings on anodized and chromatized-phosphatized aluminium.

The influence of membrane electrode assembly’s pressing on PEM fuel cell’s performance

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Federico Perdomo ◽  
Matilde Abboud ◽  
Erika Teliz ◽  
Fernando Zinola ◽  
Verónica Díaz
Keyword(s):  
Electrochemical Impedance ◽  
Linear Sweep Voltammetry ◽  
Membrane Electrode Assembly ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Polymeric Membrane ◽  
Membrane Electrode ◽  
Transfer Resistance ◽  
Supported Platinum Catalysts ◽  
Different Temperatures

Abstract The performance of a fuel cell depends on multiple factors, one of the most important being the preparation of the membrane electrode assembly (MEA). In the present work, MEAs constituted by gas diffuser electrodes (GDE) were pressed with carbon supported platinum catalysts. As solid electrolyte, a commercial polymeric membrane from Nafion was used, which was pressed at two GDE with loads of 5 and 1.5 mg/cm2 of catalyst at different temperatures and pressures for a fixed period of time. The assembly was characterized electrochemically using linear sweep voltammetry and electrochemical impedance spectroscopy at three different potentials. Also, the behavior when reversing the supply of hydrogen and oxygen to the GDE was studied. The results of the study showed a great dependence of the charge transfer resistance with the temperature, being secondary the dependence with the pressure in the range of temperature and pressure analyzed. Likewise, changes were observed in the open circuit potential after varying the temperature, pressure and catalyst load, hence affecting its maximum power and efficiency at that point.

Quantitative Determination of Triiodothyronine by Electrochemical Impedance Spectroscopic Biosensor Using Gold Nanoparticle-Modified Electrode

2020 ◽  
Vol 20 (11) ◽  
pp. 7163-7168
Author(s):  
Huynh Vu Nguyen ◽  
Anna Go ◽  
Min-Ho Lee
Keyword(s):  
Quantitative Determination ◽  
Gold Nanoparticle ◽  
Modified Electrode ◽  
Electrochemical Impedance ◽  
Low Cost ◽  
Charge Transfer Resistance ◽  
Impedance Change ◽  
Label Free ◽  
Transfer Resistance

A label-free electrochemical impedimetric immunosensor for the detection of Triiodothyronine—a thyroid hormone that functions as the biomarker for monitoring for thyroid dysfunction was developed. The gold nanoparticle-modified electrode was employed to achieve the sensitive determination of Triiodothyronine at a low concentration level. The gold nanoparticle layer on the gold electrode was generated by chronoamperometry method and its resulting characteristics were investigated by scanning electron microscopy. Redox probe [Fe(CN)6]3−/4− and electrochemical impedance spec-troscopy was used for both evaluation of the immobilization of anti-Triiodothyronine antibody on the electrode surface and quantitative determination of target Triiodothyronine in different concentrations. The electrode with absorbed antibodies showed significant changes in charge transfer resistance upon binding the antigen, which resulted in an increase in normalized impedance change as the addition of antigen concentrations over a dynamic linear range of 0.01–100 ng/ml. These results indicated that the proposed immunosensor could be a potential alternative method for determination of Triiodothyronine in clinics with the advantage of low cost and less time-consuming.

scholarly journals Impedimetric Determination of Kanamycin in Milk with Aptasensor Based on Carbon Black-Oligolactide Composite

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4738 ◽  
Author(s):  
Tatiana Kulikova ◽  
Vladimir Gorbatchuk ◽  
Ivan Stoikov ◽  
Alexey Rogov ◽  
Gennady Evtugyn ◽  
...  
Keyword(s):  
Carbon Black ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
3D Structure ◽  
Cationic Polyelectrolyte ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Chitosan Matrix ◽  
Negative Effect

The determination of antibiotics in food is important due to their negative effect on human health related to antimicrobial resistance problem, renal toxicity, and allergic effects. We propose an impedimetric aptasensor for the determination of kanamycin A (KANA), which was assembled on the glassy carbon electrode by the deposition of carbon black in a chitosan matrix followed by carbodiimide binding of aminated aptamer mixed with oligolactide derivative of thiacalix[4]arene in a cone configuration. The assembling was monitored by cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. In the presence of the KANA, the charge transfer resistance of the inner interface surprisingly decreased with the analyte concentration within 0.7 and 50 nM (limit of detection 0.3 nM). This was attributed to the partial shielding of the negative charge of the aptamer and of its support, a highly porous 3D structure of the surface layer caused by a macrocyclic core of the carrier. The use of electrostatic assembling in the presence of cationic polyelectrolyte decreased tenfold the detectable concentration of KANA. The aptasensor was successfully tested in the determination of KANA in spiked milk and yogurt with recoveries within 95% and 115%.

Study on Cu Passivation Film’s Forming Condition in HEDP Electrolyte with BTA and Chloride Ion

2013 ◽  
Vol 274 ◽  
pp. 471-474 ◽  
Author(s):  
Jin Hu Wang ◽  
Wen Jie Zhai
Keyword(s):  
Electrochemical Impedance ◽  
Processing Condition ◽  
Linear Sweep Voltammetry ◽  
Chloride Ion ◽  
Charge Transfer Resistance ◽  
Threshold Potential ◽  
Transfer Resistance ◽  
Passivation Film ◽  
Anodic Potential ◽  
Cu Passivation

The influence of corrosion inhibitor BTA, chloride ion and anodic potential on the formation of copper passivation film was studied in the electrolyte of 18wt% HEDP by using Linear Sweep Voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The results show that the increase of BTA concentration contributes to the formation of surface passivation film, and the chloride ion can promote the formation of the Cu passivation film at low concentrations but break it down when its concentration exceeds a certain limit. For each electrolyte there is a threshold anodic potential maintaining good passivation: the interfacial charge transfer resistance increases with the anodic potential when it is below the threshold potential and decreases when it is above the threshold potential. Smooth surface can be obtained by ECMP at the optimal processing condition.

scholarly journals Fabrication, characterization, and photocatalytic performance of ternary cadmium chalcogenides CdIn2S4 and Cd7.23Zn2.77S10-ZnS thin films

2020 ◽  
Vol 44 (1) ◽  
pp. 39-50
Author(s):  
Umar Daraz ◽  
Tariq Mahmood Ansari ◽  
Shafique Ahmad Arain ◽  
Muhammad Adil Mansoor ◽  
Muhammad Mazhar ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Chemical Vapor ◽  
Linear Sweep Voltammetry ◽  
Photocurrent Density ◽  
Charge Transfer Resistance ◽  
Single Step ◽  
Transfer Resistance ◽  
X Ray ◽  
Dual Source

Abstract Dithiocarbamate complexes [Cd(S2CNCy2)2(py)] (1), [In(S2CNCy2)3]·2py (2) and [Zn(S2CNCy2)2(py)] (3) were synthesized and toluene solution of (1) and (2) was used as dual source precursor for the synthesis of CdIn2S4 (CIS), while that of (1) and (3) was applied for the deposition of Cd7.23Zn2.77S10–ZnS composite (CZS-ZS) thin film photoan-odes by employing single step aerosol assisted chemical vapor deposition (AACVD) technique. Deposition experiments were performed at 500°C under an inert ambient of argon gas. The structural properties of deposited films were evaluated by using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The field emission scanning electron microscopy (FESEM) exposed surface morphologies while UV-Visible spectrophotometry revealed that CIS is low band gap photoanode in comparison to CZS-ZS. The comparison of photoelectrochemical (PEC) responses measured in identical conditions in terms of linear sweep voltammetry (LSV) depicts photocurrent density of 4.4 mA /cm2 and 2.9 mA/cm2 at applied potential of 0.7 V under solar light intensity of 100 mW/cm2 for CIS and CZS-ZS respectively. Further, electrochemical impedance spectroscopy (EIS) confirms that PEC properties of CIS are superior to CZS-ZS photoanode as the former offer less charge transfer resistance (Rct) 0.03 MΩ in comparison to CZS-ZS having Rct value of 0.06 MΩ.

scholarly journals The Experimental Verification of a Generalized Model of Equivalent Circuits

2021 ◽  
Vol 49 (1) ◽  
pp. 1-8
Author(s):  
Zoltán Lukács ◽  
Dávid Baccilieri ◽  
Tamás Kristóf
Keyword(s):  
Charge Transfer ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Mathematical Treatment ◽  
Frequency Range ◽  
Transfer Resistance ◽  
Generalized Model ◽  
Fitting In ◽  
Adsorption Desorption

The determination of typical parameters of electrochemical systems, e.g. the polarization or charge transfer resistances, can be critical with regard to the application of Electrochemical Impedance Spectroscopy (EIS) if the lower frequency range is biased as a result of transport and/or adsorption/desorption processes. In such cases, the charge transfer resistance should be assessed from the higher frequency range which is typically inadequate in itself as an input for nonlinear parameter fitting. In earlier publications, an alternative mathematical treatment of both the Equivalent Circuit (EC) and of the parameter dispersion was provided using a generalized model of ECs and also a dispersion-invariant model of the electrochemical interface. In the present work, the previously presented experimental EIS results were crosschecked to verify the performance of the generalized model against a series of redox and corrosion systems. The results proved that the applied method is consistent and provides a fairly good correlation between the principal resistance data assessed by different methods.

scholarly journals Operation and Electro(chemical) characterization of a microbial fuel cell stack fed with fermentable household waste extract

2019 ◽  
Keyword(s):  
Microbial Fuel Cells ◽  
Electrochemical Impedance ◽  
Voltage Drop ◽  
Chemical Characterization ◽  
Linear Sweep Voltammetry ◽  
Charge Transfer Resistance ◽  
Household Waste ◽  
Transfer Resistance ◽  
In Series ◽  
Waste Extract

<p>Two identical four air-cathode single chamber membrane-less microbial fuel cells were stacked and tested under in series and in parallel electrical configurations. Fermentable household waste extract (FORBI; 0.8 g COD/L) was used as substrate, in all cases. Linear Sweep Voltammetry (LSV) was carried out for the construction of polarization curves which revealed that the highest power ouput (3.88 mW) was obtained under parallel connection as in series connection was found lower due to voltage drop phenomena. Electrochemical Impedance Spectroscopy measurements (EIS) gave an insight in the electrochemical processes occurring within the stack under both electrical connections. The contribution of the individual resistances to the overall internal resistance was defined, designating the significant role of the solution resistance (Rs) and the charge transfer resistance (RCT) under closed circuit conditions.</p>

scholarly journals A Surface Network Based on Polytyramine/ Gold Nanoparticles: Characterization, Kinetics, Thermodynamics and Selective Determination of Norepinephrine

2021 ◽  
Vol 26 (1) ◽  
pp. 8-21
Author(s):  
Emad A. Khudaish ◽  
Arwa Al-Maskari
Keyword(s):  
Gold Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Differential Pulse ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Selective Determination ◽  
Irreversible Reaction ◽  
Nanoparticles Characterization

A solid-state sensor was fabricated by a spontaneous electrochemical deposition of polytyramine (Ptyr) film onto a glassy carbon electrode (GCE) which was further peripherally supported by gold nanoparticles (AuNPs). The surface materials of the developed sensor (AuNPs.Ptyr-GCE) were characterized by X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The rate constant of charge transfers (kct) of the as-prepared sensor (8.77 × 10-4 cm/s) was evaluated by fitting the charge transfer resistance (Rct) data in the presence of ferric-ferrous hexacyanide redox couple solution, [Fe(CN)6]3-/4-. The voltammetric behavior of norepinephrine (NOR) was confirmed to follow an irreversible reaction mechanism at which the estimated diffusion coefficient value was 7.39 × 10-5 cm2/s. The sensor showed a large enhancement on NOR oxidation and comparatively lowered its detection limit (DL3s) to 0.130 mM (22 ppb). It was also applied for selective determination of NOR in the presence of high concentrations of ascorbic acid (AA) and uric acid (UA). The interference study highlighted the great stability of the proposed sensor by generating a similar sensitivity as in the pure NOR solution. The analytical performance of the proposed system was validated successfully for pharmaceutical and biological samples with tolerable recovery percentages.

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