scholarly journals Oxygen Diffusion and Surface Exchange Coefficients of Porous La0.6Sr0.4Co0.2Fe0.8O3-δ Decorated with Co3O4 Nanoparticles

2022 ◽  
Author(s):  
Julian Ascolani-Yael ◽  
Alejandra Montenegro-Hernandez ◽  
Laura C. Baqué ◽  
Lucía M. Toscani ◽  
Alberto Caneiro ◽  
...  
Keyword(s):  
Polarization Resistance ◽  
Surface Reaction ◽  
Electrochemical Impedance ◽  
Active Role ◽  
Co3o4 Nanoparticles ◽  
Surface Exchange ◽  
Eis Measurements ◽  
Electrochemical Model ◽  
Ion Incorporation ◽  
Tomography Data

Abstract This work presents a comparative study of the diffusion (Dchem) and surface exchange coefficients (kchem) of porous La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and Co3O4 nanoparticles decorated LSCF electrodes. The study was carried out using the 3DT-EIS method, which combines Electrochemical Impedance Spectroscopy experiments with FIB-SEM tomography data through an adapted Transmission Line - Adler Lane Steele electrochemical model. A reduction of the polarization resistance of about 60% was measured for the Co3O4 decorated LSCF respect to the reference LSCF cathode, in air at 700 °C. The Co3O4 decoration was found to modify the ORR surface reaction limiting mechanism from O2 dissociation to O-ion incorporation, whereas the diffusion coefficient was not modified by the decoration, which represents a surface diffusion process for both electrodes. After the EIS measurements, the Co3O4 particles were almost no longer visible by Field-Emission SEM on the surface of the decorated sample, but signs that these particles play an active role in Sr Segregation were observed by STEM-EDS, in particular by concentrating the segregated SrO in the surroundings of the decorated particles.

scholarly journals The effects of time-variance on impedance measurements: examples of a corroding electrode and a battery cell

2020 ◽  
Vol 10 (2) ◽  
pp. 127-140 ◽  
Author(s):  
Nicolas Murer ◽  
Jean-Paul Diard ◽  
Bogdan Petrescu
Keyword(s):  
Polarization Resistance ◽  
Electrochemical Impedance ◽  
Steel Sample ◽  
Impedance Method ◽  
Battery Cell ◽  
Low Frequencies ◽  
Impedance Measurements ◽  
Time Variance ◽  
Eis Measurements ◽  
Resistance Decrease

When performing electrochemical impedance spectroscopy (EIS) measurements on a system, we must make sure it fulfills certain conditions. One of them is that it should be stationary that is to say, steady-state and time-invariant. Commonly studied systems are time-variant, for example a corroding electrode or a battery under operation. A corroding electrode sees its polarization resistance decrease with time. A passivating electrode sees its polarization resistance increase with time. These phenomena cause a deformation of the Nyquist impedance at low frequencies. This result was first simulated and validated by experimental measurements on a corroding steel sample undergoing uniform cor­rosion. The effect of performing impedance measurements on a discharging battery was also shown. Several methods are available to check and correct time-variance. The non-stationary distortion (NSD) indicator is used to separate valid and invalid data samples and the so called “4D impedance” method can easily produce instantaneous impedance data.

scholarly journals Inhibitory Effect of Ethanolic Extract of Propolis on Corrosion of Ferritic Stainless Steel in Chloride Media

2019 ◽  
Vol 33 (2) ◽  
pp. 213-219 ◽  
Author(s):  
Luiza Marilac Pereira Dolabella ◽  
Thalys Eduardo dos Santos ◽  
Tulio Matencio ◽  
Wander Luiz Vasconcelos ◽  
Vanessa Lins
Keyword(s):  
Stainless Steel ◽  
Polarization Resistance ◽  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Ethanolic Extract ◽  
Inhibitory Effect ◽  
Aqueous Sodium Chloride Solution ◽  
Maximum Inhibition ◽  
Eis Measurements ◽  
Ethanolic Extract Of Propolis

This work evaluates the inhibitory effect of ethanolic extract of propolis (EEP) on the corrosion of AISI 409 stainless steel (SS) in chloride media. Additions of 100, 200, and 500 μL of EEP in an aqueous sodium chloride solution were performed. The inhibitory effect on the SS was evaluated using electrochemical impedance spectroscopy (EIS) measurements up to 720 hours in immersion. EEP additions of 200 μL and 500 μL increased the polarization resistance of the SS. After 720 hours of immersion, the highest impedance was identified for the SS in solution with 500 μL of EEP. The maximum inhibition efficiency observed for addition of 500 μL of EEP in solution was 98.1 %, after 360 h of immersion.

Efficiency Comparison of some Natural Products on Corrosion Inhibition of Al-Mg-Si Alloy

2011 ◽  
Vol 328-330 ◽  
pp. 1206-1209 ◽  
Author(s):  
R. Rosliza ◽  
W.B. Wan Nik ◽  
Sudin Izman
Keyword(s):  
Natural Products ◽  
Corrosion Inhibition ◽  
Polarization Resistance ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Tapioca Starch ◽  
Linear Polarization Resistance ◽  
Efficiency Comparison ◽  
Eis Measurements ◽  
Natural Honey

The comparison of the efficiency of some natural products (natural honey, vanillin and tapioca starch) on corrosion inhibition of Al-Mg-Si alloy is investigated in seawater solution at room temperature, using potentiodynamic polarization (PP), linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) measurements. The evolution of the corrosion potential (Ecorr) and corrosion current density (icorr) obtained from Tafel extrapolation of polarization curves, and the polarization resistance (Rp) values determined from LPR and EIS measurements indicate that the corrosion rates of Al-Mg-Si alloy decrease with the increasing the natural products concentration. In all cases, the increasing order of inhibition efficiency is: Natural honey < Vanillin < Tapioca starch.

scholarly journals Corrosion Resistance of a Plasma-Oxidized Ti6Al4V Alloy for Dental Applications

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1136
Author(s):  
N. Velazquez-Torres ◽  
J. Porcayo-Calderon ◽  
H. Martinez-Valencia ◽  
R. Lopes-Cecenes ◽  
I. Rosales-Cadena ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Polarization Resistance ◽  
Electrochemical Impedance ◽  
Artificial Saliva ◽  
Corrosion Current ◽  
Ti6al4v Alloy ◽  
Free Corrosion Potential ◽  
Density Values ◽  
Eis Measurements ◽  
Dental Applications

A Ti6Al4V alloy was plasma-oxidized at 600 °C during 1, 2, 3, 5 and 8 h and corroded in an artificial saliva solution. Electrochemical evaluation was performed by using potentiodynamic polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) measurements during 100 h. Corroded specimens were characterized by using Raman spectroscopy and scanning electronic microscopy (SEM). All tests indicated that the highest corrosion resistance was obtained for specimen oxidized during 3 h since the noblest free corrosion potential, lowest passive and corrosion current density values, as well as the highest polarization resistance values were obtained under these circumstances. EIS measurements indicated that the highest impedance and phase angle values obtained for this specimen exhibited a high capacitive behavior typical of a very compact passive film.

scholarly journals Oxidation Behavior of an Austenitic Steel (Fe, Cr and Ni), the 310 H, in a Deaerated Supercritical Water Static System

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 571
Author(s):  
Aurelia Elena Tudose ◽  
Ioana Demetrescu ◽  
Florentina Golgovici ◽  
Manuela Fulger
Keyword(s):  
Stainless Steel ◽  
Supercritical Water ◽  
Nuclear Reactor ◽  
Electrochemical Impedance ◽  
Electrochemical Methods ◽  
Metallographic Analysis ◽  
Gravimetric Analysis ◽  
Static System ◽  
Eis Measurements ◽  
Supercritical Temperature

The aim of this work was to study the corrosion behavior of a Fe-Cr-Ni alloy (310 H stainless steel) in water at a supercritical temperature of 550 °C and a pressure of 250 atm for up to 2160 h. At supercritical temperature, water is a highly aggressive environment, and the corrosion of structural materials used in a supercritical water-cooled nuclear reactor (SCWR) is a critical problem. Selecting proper candidate materials is one key issue for the development of SCWRs. After exposure to deaerated supercritical water, the oxides formed on the 310 H SS surface were characterized using a gravimetric analysis, a metallographic analysis, and electrochemical methods. Gravimetric analysis showed that, due to oxidation, all the tested samples gained weight, and oxidation of 310H stainless steel at 550 °C follows parabolic rate, indicating that it is driven by a diffusion process. The data obtained by microscopic metallography concord with those obtained by gravimetric analysis and show that the oxides layer has a growing tendency in time. At the same time, the results obtained by electrochemical impedance spectroscopy (EIS) measurements indicate the best corrosion resistance of Cr, and (Fe, Mn) Cr2O4 oxides developed on the samples surface after 2160 h of oxidation. Based on the results obtained, a strong correlation between gravimetric analysis, metallographic analysis, and electrochemical methods was found.

scholarly journals Experimental, DFT and MD Assessments of Bark Extract of Tamarix aphylla as Corrosion Inhibitor for Carbon Steel Used in Desalination Plants

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3679
Author(s):  
Ismat H. Ali
Keyword(s):  
Corrosion Inhibitor ◽  
Potentiodynamic Polarization ◽  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Effect Of Temperature ◽  
Bark Extract ◽  
Plant Sample ◽  
Gravimetric Analysis ◽  
Sample Collection ◽  
Eis Measurements

This study aimed to examine the extract of barks of Tamarix aphylla as a corrosion inhibitor. The methodology briefly includes plant sample collection, extraction of the corrosion inhibitor, gravimetric analysis, plotting potentiodynamic polarization plots, electrochemical impedance spectroscopic measurements, optimization of conditions, and preparation of the inhibitor products. The results show that the values of inhibition efficiency (IE%) increased as the concentrations of the inhibitor increased, with a maximum achievable inhibition efficiency of 85.0%. Potentiodynamic polarization (PP) tests revealed that the extract acts as a dual-type inhibitor. The results obtained from electrochemical impedance spectroscopy (EIS) measurements indicate an increase in polarisation resistance, confirming the inhibitive capacity of the tested inhibitor. The adsorption of the inhibitor on the steel surface follows the Langmuir adsorption isotherm model and involves competitive physio-sorption and chemisorption mechanisms. The EIS technique was utilized to investigate the effect of temperature on corrosion inhibition within the 298–328 K temperature range. Results confirm that the inhibition efficiency (IE%) of the inhibitor decreased slightly as the temperature increased. Lastly, the thermodynamic parameters for the inhibitor were calculated.

Electrochemical Performance Optimization of Li2NixFe1−xSiO4 Cathode Materials for Lithium-Ion Batteries

2017 ◽  
Vol 14 (2) ◽  
Author(s):  
Atef Y. Shenouda ◽  
M. M. S. Sanad
Keyword(s):  
Performance Optimization ◽  
Electrochemical Impedance ◽  
Coulombic Efficiency ◽  
Sol Gel ◽  
Lithium Ion ◽  
Electrochemical Impedance Spectra ◽  
Cell Parameters ◽  
Sol Gel Process ◽  
Eis Measurements ◽  
And Function

Li2NixFe1−xSiO4 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) samples were prepared by sol–gel process. The crystal structure of prepared samples of Li2NixFe1−xSiO4 was characterized by XRD. The different crystallographic parameters such as crystallite size and lattice cell parameters have been calculated. Scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) investigations were carried out explaining the morphology and function groups of the synthesized samples. Furthermore, electrochemical impedance spectra (EIS) measurements are applied. The obtained results indicated that the highest conductivity is achieved for Li2Ni0.4Fe0.6SiO4 electrode compound. It was observed that Li/Li2Ni0.4Fe0.6SiO4 battery has initial discharge capacity of 164 mAh g−1 at 0.1 C rate. The cycle life performance of all Li2NixFe1−xSiO4 batteries was ranged between 100 and 156 mAh g−1 with coulombic efficiency range between 70.9% and 93.9%.

scholarly journals Electrochemical Impedance of Hydrogenated Phases of ZnO and CuO Nanoparticles for Electrode Applications

2020 ◽  
pp. 1-6
Author(s):  
L. I. Menegbo ◽  
J. L. Konne ◽  
N. Boisa
Keyword(s):  
Electrochemical Impedance ◽  
Sol Gel ◽  
Low Frequency ◽  
High Gain ◽  
High Frequency Region ◽  
Nyquist Plots ◽  
Eis Measurements ◽  
Xrd Patterns ◽  
Straight Lines ◽  
First Time

The Electrochemical Impedance Spectroscopy (EIS) measurements of Sol-gel synthesized ZnO, CuO and their respective hydrogenated phases (ZnO:H and CuO:H) for  a proton-type battery model has been reported for the first time. The XRD patterns confirmed that CuO and ZnO were phase pure with minor impurities. However, that of CuO:H showed mixed phases of CuO and Cu2O with the later  appearing prominent. The estimated particle sizes of ZnO, ZnO:H, CuO and CuO:H obtained using Scherrers’ equation were 17.83, 17.75, 21.63 and 15.42 nm respectively, showing remarkable particle size reductions upon hydrogenation as oxygen vacancies were substituted with smaller hydrogen ions. Nyquist plots from the EIS experimental data recorded over a frequency range of 100 kHz – 5 mHz showed expected flat semicircles at the high frequency region and straight lines at the low frequency regions while resistance estimations from the intercepts of the Bode plots were 12.10, 7.80, 16.00 and 10.80 Ω for ZnO, ZnO:H, CuO and CuO:H respectively. It also indicated high gain margins suggesting impressive electrochemical properties for battery applications.

scholarly journals Electrochemical properties of Fe2O3/AB based composite electrodes in alkaline solution

2019 ◽  
Vol 35 (3) ◽  
Author(s):  
Trinh Tuan Anh ◽  
Bui Thi Hang
Keyword(s):  
Iron Oxide ◽  
Alkaline Solution ◽  
Electrochemical Impedance ◽  
Passive Layer ◽  
Composite Electrodes ◽  
Iron Oxide Particles ◽  
Electrochemical Behaviors ◽  
Suitable Material ◽  
Oxide Electrodes ◽  
Eis Measurements

To find a suitable material for Fe-air battery anode, Fe2O3 nanoparticles (nm) and microparticles (µm) were used as active materials and Acetylene Black carbon (AB) as additive to prepare Fe2O3/AB composites. The effect of grain size of iron oxide particles and additives on the electrochemical behavior of Fe2O3/AB composite electrodes in alkaline solution have been investigated using cyclic voltammetry (CV), galvanostatic cycling and electrochemical impedance spectroscopy (EIS) measurements. Iron oxide nanoparticles provided better cyclability than iron oxide microparticles. Impedance of electrode increased during cycling but the nm-Fe2O3/AB electrode gave smaller resistance than µm-Fe2O3/AB one. The additives showed strongly effects on the electrochemical behaviors of iron oxide electrodes. The AB additive enhanced the electric conductivity of Fe2O3/AB electrode and thus increased the redox reaction rate of iron oxide while K2S interacted and broke down the passive layer leading to improved cyclability and giving higher capacity for Fe2O3/AB electrodes.

scholarly journals Synthesis, Characterization and Corrosion Protective Efficiency of 2[2-Oxo-phenyl hydrazinyl ethyl] benzamide on Mild Steel in Sulphuric Acid Medium

2010 ◽  
Vol 7 (2) ◽  
pp. 331-340
Author(s):  
Rinki Goel ◽  
Weqar A. Siddiqi ◽  
V. M. Chaubey ◽  
Bahar Ahmed
Keyword(s):  
Mild Steel ◽  
Acid Medium ◽  
Electrochemical Impedance ◽  
Protective Efficiency ◽  
Inhibitor Molecule ◽  
Protection Efficiency ◽  
Langmuir Isotherm Model ◽  
Eis Measurements ◽  
Increasing Temperature ◽  
Good Agreement

2[2-Oxo-phenyl hydrazinyl ether] benzamide (2BA) was synthesized, characterized and tested effective for corrosion inhibition of mild steel in 1 N H2SO4solution using galvanodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Polarization resistances calculated from the EIS measurements are in good agreement with those obtained from alternating current (AC) polarization measurements. The mild steel samples were also analyzed by Scanning Electron Microscopy (SEM). The result showed that 2BA is an excellent inhibitor for mild steel in acid medium. The inhibition was assumed to occurviaadsorption of the inhibitor molecule on the metal surface. In the 303-323K temperature range, the 2BA adsorption follows Langmuir isotherm model. The protection efficiency increases with increasing the inhibitor concentration in the range of 250-1000 ppm but slightly decreases with increasing temperature.

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