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

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.

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Electrodeposition Kinetics of Ni/Nano-Y2O3 Composite Coatings

Metals ◽

10.3390/met8090669 ◽

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.

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

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2021-0065 ◽

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.

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Developing Activated Carbon Veil Electrode for Sensing Salivary Uric Acid

Biosensors ◽

10.3390/bios11080287 ◽

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.

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

Main Group Metal Chemistry ◽

10.1515/mgmc-2021-0008 ◽

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.

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A Combinatorial Electrochemical Biosensor for Sweat Biomarker Benchmarking

SLAS TECHNOLOGY Translating Life Sciences Innovation ◽

10.1177/2472630319882003 ◽

2019 ◽

Vol 25 (1) ◽

pp. 25-32 ◽

Cited By ~ 2

Author(s):

Antra Ganguly ◽

Paul Rice ◽

Kai-Chun Lin ◽

Sriram Muthukumar ◽

Shalini Prasad

Keyword(s):

Electrochemical Sensors ◽

Electrochemical Impedance ◽

Flexible Substrate ◽

Chloride Ion ◽

Charge Transfer Resistance ◽

Open Circuit ◽

Label Free ◽

Transfer Resistance ◽

Disease Biomarker ◽

Sweat Chloride

Misclassification of an acute disease condition as chronic and vice versa by electrochemical sweat biomarker sensors can cause significant psychological, emotional, and financial stress among patients. To achieve higher accuracy in distinguishing between a chronic condition and an acute condition, there is a need to establish a reference biomarker to index the actual chronic disease biomarker of interest by combinatorial sensing. This work provides the first technological proof of leveraging the chloride ion content in sweat for a combinatorial sweat biomarker benchmarking scheme. In this scheme, the sweat chloride ion has been demonstrated as the reference/indexing biomarker, while sweat cortisol has been studied as the disease biomarker of interest. Label-free affinity biosensing is achieved by using a two-electrode electrochemical system on a flexible substrate suitable for wearable applications. The electrochemical stability of the fabricated electrodes for biosensing applications was studied by open-circuit potential measurements. Attenuated total reflectance–Fourier transform infrared spectroscopy spectra validate the crosslinker–antibody binding chemistry. Concentration-dependent analyte–capture probe binding induces a modulation in the electrical properties (charge transfer resistance and double-layer capacitance) at the electrode–sweat buffer interface, which are transduced by nonfaradaic electrochemical impedance spectroscopy (EIS). Calibration dose responses for the sensor for cortisol (5–200 ng/mL) and chloride (10–100 mM) detection were evaluated in synthetic (pH 6) and pooled human sweat ( R2 > 0.95). The variation in the cortisol sensor response due to fluctuations in sweat chloride levels and the significance of reporting normalized biomarker levels were demonstrated to further emphasize the need for biomarker benchmarking in electrochemical sensors.

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

Global NEST Journal ◽

10.30955/gnj.002996 ◽

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

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.

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Improvement of Ti/RuO2–IrO2 Anode Lifetime and Electrocatalytical Properties by Using an Eco-Friendly Thermal Decomposition Method Using Polyvinyl Alcohol as Solvent

10.26434/chemrxiv.7991129 ◽

2019 ◽

Author(s):

Charlys Bezerra ◽

Géssica Santos ◽

Marilia Pupo ◽

Maria Gomes ◽

Ronaldo Silva ◽

...

Keyword(s):

Thermal Decomposition ◽

Polyvinyl Alcohol ◽

High Efficiency ◽

Electrochemical Impedance ◽

Pechini Method ◽

Low Cost ◽

Charge Transfer Resistance ◽

Transfer Resistance ◽

Calcination Temperatures ◽

Service Lifetime

Electrochemical oxidation processes are promising solutions for wastewater treatment due to their high efficiency, easy control and versatility. Mixed metal oxides (MMO) anodes are particularly attractive due to their low cost and specific catalytic properties. Here, we propose an innovative thermal decomposition methodology using <a>polyvinyl alcohol (PVA)</a> as a solvent to prepare Ti/RuO2–IrO2 anodes. Comparative anodes were prepared by conventional method employing a polymeric precursor solvent (Pechini method). The calcination temperatures studied were 300, 400 and 500 °C. The physical characterisation of all materials was performed by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy, while electrochemical characterisation was done by cyclic voltammetry, accelerated service lifetime and electrochemical impedance spectroscopy. Both RuO2 and IrO2 have rutile-type structures for all anodes. Rougher and more compact surfaces are formed for the anodes prepared using PVA. Amongst temperatures studied, 300 °C using PVA as solvent is the most suitable one to produce anodes with expressive increase in voltammetric charge (250%) and accelerated service lifetime (4.3 times longer) besides reducing charge-transfer resistance (8 times lower). Moreover, the electrocatalytic activity of the anodes synthesised with PVA toward the Reactive Blue 21 dye removal in chloride medium (100 % in 30 min) is higher than that prepared by Pechini method (60 min). Additionally, the removal total organic carbon point out improved mineralisation potential of PVA anodes. Finally, this study reports a novel methodology using PVA as solvent to synthesise Ti/RuO2–IrO2 anodes with improved properties that can be further extended to synthesise other MMO compositions.

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Electrochemical Immunosensor for the Quantification of S100B at Clinically Relevant Levels Using a Cysteamine Modified Surface

Sensors ◽

10.3390/s21061929 ◽

2021 ◽

Vol 21 (6) ◽

pp. 1929

Author(s):

Alexander Rodríguez ◽

Francisco Burgos-Flórez ◽

José D. Posada ◽

Eliana Cervera ◽

Valtencir Zucolotto ◽

...

Keyword(s):

Frequency Analysis ◽

Surface Characterization ◽

Electrochemical Impedance ◽

Limit Of Detection ◽

Neuronal Damage ◽

Charge Transfer Resistance ◽

Single Frequency ◽

Response Analysis ◽

Transfer Resistance ◽

Therapeutic Decisions

Neuronal damage secondary to traumatic brain injury (TBI) is a rapidly evolving condition, which requires therapeutic decisions based on the timely identification of clinical deterioration. Changes in S100B biomarker levels are associated with TBI severity and patient outcome. The S100B quantification is often difficult since standard immunoassays are time-consuming, costly, and require extensive expertise. A zero-length cross-linking approach on a cysteamine self-assembled monolayer (SAM) was performed to immobilize anti-S100B monoclonal antibodies onto both planar (AuEs) and interdigitated (AuIDEs) gold electrodes via carbonyl-bond. Surface characterization was performed by atomic force microscopy (AFM) and specular-reflectance FTIR for each functionalization step. Biosensor response was studied using the change in charge-transfer resistance (Rct) from electrochemical impedance spectroscopy (EIS) in potassium ferrocyanide, with [S100B] ranging 10–1000 pg/mL. A single-frequency analysis for capacitances was also performed in AuIDEs. Full factorial designs were applied to assess biosensor sensitivity, specificity, and limit-of-detection (LOD). Higher Rct values were found with increased S100B concentration in both platforms. LODs were 18 pg/mL(AuES) and 6 pg/mL(AuIDEs). AuIDEs provide a simpler manufacturing protocol, with reduced fabrication time and possibly costs, simpler electrochemical response analysis, and could be used for single-frequency analysis for monitoring capacitance changes related to S100B levels.

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Influence of HAP on the Morpho-Structural Properties and Corrosion Resistance of ZrO2-Based Composites for Biomedical Applications

Crystals ◽

10.3390/cryst11020202 ◽

2021 ◽

Vol 11 (2) ◽

pp. 202

Author(s):

Réka Barabás ◽

Carmen Ioana Fort ◽

Graziella Liana Turdean ◽

Liliana Bizo

Keyword(s):

Electrochemical Impedance ◽

Artificial Saliva ◽

Synergetic Effect ◽

Composite Layer ◽

Charge Transfer Resistance ◽

Processing Route ◽

Dental Alloys ◽

Metallic Electrode ◽

Transfer Resistance ◽

X Ray

In the present work, ZrO2-based composites were prepared by adding different amounts of antibacterial magnesium oxide and bioactive and biocompatible hydroxyapatite (HAP) to the inert zirconia. The composites were synthesized by the conventional ceramic processing route and morpho-structurally analyzed by X-ray powder diffraction (XRPD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Two metallic dental alloys (i.e., Ni–Cr and Co–Cr) coated with a chitosan (Chit) membrane containing the prepared composites were exposed to aerated artificial saliva solutions of different pHs (i.e., 4.3, 5, 6) and the corrosion resistances were investigated by electrochemical impedance spectroscopy technique. The obtained results using the two investigated metallic dental alloys shown quasi-similar anticorrosive properties, having quasi-similar charge transfer resistance, when coated with different ZrO2-based composites. This behavior could be explained by the synergetic effect between the diffusion process through the Chit-composite layer and the roughness of the metallic electrode surface.

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