Electrodeposition Kinetics of Ni/Nano-Y2O3 Composite Coatings

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.

Download Full-text

Deciphering the Disaggregation Mechanism of Amyloid Beta Aggregate by 4-(2-Hydroxyethyl)-1-Piperazinepropanesulfonic Acid Using Electrochemical Impedance Spectroscopy

Sensors ◽

10.3390/s21030788 ◽

2021 ◽

Vol 21 (3) ◽

pp. 788

Author(s):

Hien T. Ngoc Le ◽

Sungbo Cho

Keyword(s):

Electrochemical Impedance Spectroscopy ◽

Impedance Spectroscopy ◽

Electrochemical Impedance ◽

Specific Binding ◽

Amyloid Β ◽

Electrochemical Measurement ◽

Charge Transfer Resistance ◽

Chemical Agent ◽

Transfer Resistance ◽

K Value

Aggregation of amyloid-β (aβ) peptides into toxic oligomers, fibrils, and plaques is central in the molecular pathogenesis of Alzheimer’s disease (AD) and is the primary focus of AD diagnostics. Disaggregation or elimination of toxic aβ aggregates in patients is important for delaying the progression of neurodegenerative disorders in AD. Recently, 4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid (EPPS) was introduced as a chemical agent that binds with toxic aβ aggregates and transforms them into monomers to reduce the negative effects of aβ aggregates in the brain. However, the mechanism of aβ disaggregation by EPPS has not yet been completely clarified. In this study, an electrochemical impedimetric immunosensor for aβ diagnostics was developed by immobilizing a specific anti-amyloid-β (aβ) antibody onto a self-assembled monolayer functionalized with a new interdigitated chain-shaped electrode (anti-aβ/SAM/ICE). To investigate the ability of EPPS in recognizing AD by extricating aβ aggregation, commercially available aβ aggregates (aβagg) were used. Electrochemical impedance spectroscopy was used to probe the changes in charge transfer resistance (Rct) of the immunosensor after the specific binding of biosensor with aβagg. The subsequent incubation of the aβagg complex with a specific concentration of EPPS at different time intervals divulged AD progression. The decline in the Rct of the immunosensor started at 10 min of EPPS incubation and continued to decrease gradually from 20 min, indicating that the accumulation of aβagg on the surface of the anti-aβ/SAM/ICE sensor has been extricated. Here, the kinetic disaggregation rate k value of aβagg was found to be 0.038. This innovative study using electrochemical measurement to investigate the mechanism of aβagg disaggregation by EPPS could provide a new perspective in monitoring the disaggregation periods of aβagg from oligomeric to monomeric form, and then support for the prediction and handling AD symptoms at different stages after treatment by a drug, EPPS.

Download Full-text

PREPARATION AND INVESTIGATION OF ELECTRODEPOSITED Ni–NANO-Cr2O3 COMPOSITE COATINGS

Surface Review and Letters ◽

10.1142/s0218625x15501115 ◽

2016 ◽

Vol 23 (02) ◽

pp. 1550111 ◽

Cited By ~ 3

Author(s):

JIBO JIANG ◽

CHENQI FENG ◽

WEI QIAN ◽

LIBIN YU ◽

FENGYING YE ◽

...

Keyword(s):

Electrochemical Impedance ◽

Composite Coatings ◽

Charge Transfer Resistance ◽

X Ray Diffraction ◽

Transfer Resistance ◽

X Ray ◽

Potentiodynamic Polarization Curves ◽

Nucleation Sites ◽

Passive Transition ◽

Steel Surfaces

The electrodeposition of Ni–nano-Cr2O3 composite coatings was studied in electrolyte containing different contents of Cr2O3 nanoparticles (Cr2O3 NPs) on mild steel surfaces. Some techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness, the potentiodynamic polarization curves (Tafel) and electrochemical impedance spectroscopy (EIS) were used to compare pure Ni coatings and Ni–nano-Cr2O3 composite coatings. The results show that the incorporation of Cr2O3 NPs resulted in an increase of hardness and corrosion resistance, and the maximum microhardness of Ni-nano-Cr2O3 composite coatings reaches about 495 HV. The coatings exhibit an active-passive transition and relatively large impedance values. Moreover, the effect of Cr2O3 NPs on Ni electrocrystallization is also investigated by cyclic voltammetry (CV) and EIS spectroscopy, which demonstrates that the nature of Ni-based composite coatings changes attributes to Cr2O3 NPs by offering more nucleation sites and less charge transfer resistance.

Download Full-text

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.

Download Full-text

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.

Download Full-text

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

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.274.471 ◽

2013 ◽

Vol 274 ◽

pp. 471-474 ◽

Cited By ~ 1

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.

Download Full-text

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.

Download Full-text

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.

Download Full-text

EFFECT OF NI DOPING ON SOME PROPERTIES OF ELECTRODEPOSITED ZINC ALLOY COATINGS

Acta Metallurgica Slovaca ◽

10.12776/ams.v21i3.472 ◽

2015 ◽

Vol 21 (3) ◽

pp. 226 ◽

Cited By ~ 3

Author(s):

Malika DIAFI ◽

Nadjette Belhamra ◽

Hachemi Ben Temam ◽

Brahim Gasmi ◽

Said Benramache

Keyword(s):

Electrochemical Impedance ◽

Composite Coatings ◽

Charge Transfer Resistance ◽

Zinc Alloy ◽

Diffraction Measurement ◽

Micro Hardness ◽

Ni Doping ◽

Corrosion Properties ◽

Transfer Resistance ◽

Characterization Methods

In this work an experimental study Zinc- nickel composite coatings was conducted. For this, the influence of the concentration of Ni is the principal object in order to improve the corrosion resistance of the deposit, which has been made by electroplating on steel substrates previously treated, have been studied by several characterization methods, as the X-ray diffraction, measurement of micro hardness and scanning electron microscopy (SEM), protection against corrosion properties studied in a solution of 3 % NaCl in the potentiodynamic polarization measurements (Tafel), electrochemical impedance spectroscopy (EIS) to the potential of corrosion free. The parameters that characterize the corrosion behavior can be determined from the plots and Nyquist plots. Trends of increasing the charge transfer resistance and the decrease of capacitance values. XRD and SEM results and identify any coatings Zn-Ni alloy composition have similar phase (simple cubic γ-phase structure) and the addition of Ni in the zinc matrix increases the micro-hardness, and we note the maximum hardness is obtained for 0.2M Ni.

Download Full-text

Correlating the Layer Properties of Ni-alumina Composite Coatings and the Mechanism of Codeposition

International Journal of Chemistry ◽

10.5539/ijc.v8n2p110 ◽

2016 ◽

Vol 8 (2) ◽

pp. 110 ◽

Cited By ~ 1

Author(s):

Amir Sadeghi ◽

Maximilian Sieber ◽

Hosein Hasannejad ◽

Ingolf Scharf ◽

Thomas Lampke

Keyword(s):

Double Layer ◽

Electrochemical Impedance ◽

Composite Coatings ◽

Charge Transfer Resistance ◽

Nano Particles ◽

Submicron Particles ◽

Transfer Resistance ◽

Alumina Particles ◽

Alumina Composite ◽

The Impact

Ni-Al2O3 composite coatings electrodeposited from Watt’s electrolyte include Al2O3 nano-and submicron particles. The effect of particle size and concentration of the particles in the electrolyte were investigated on the morphology and incorporation value of particles into the deposits. The influence of alumina particles on the electrodeposition behavior of Ni was also studied by means of electrochemical impedance spectroscopy. The results achieved from the impedance measurements and the correlation with the layer characterization could help to better understand the codeposition mechanism derived from the impact of different particle characteristics including size and concentration on the nature of the double-layer. The increase in the concentration of particles from 1 to 20 g/l resulted in an increase of the double-layer capacity and decrease of the charge transfer resistance, while the addition of submicron particles had a higher influence on the characteristics of the double-layer compared to the nano particles. Although the alumina particles with submicron size could stimulate the incorporation of particles faster than those with nano size, the strengthening performance of the layers not only depended on the incorporation value of the particles, but also on the microstructure of the deposits.

Download Full-text

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.

Download Full-text