EIS Methods Research Articles

Sustainable development of an effective anti-corrosion film over the St12-steel surface against seawater attacks using Ce(III) ions/tri-sodium phosphate anions

One application of organic compounds is to utilize them as corrosion inhibitors in acidic environments to diminish steel corrosion. These inhibitors do not show very good inhibition properties in saline (NaCl) environments. There have been many studies on boosting these inhibitors’ performance in such environments (especially Cl− containing media). One of the ways that have been proposed is the use of organic and inorganic inhibitors, simultaneously. The synergistic effect of these inhibitors has shown promising results in reducing steel corrosion. In this study, cerium(III) nitrate and tri-sodium phosphate (TSP) was used as organic and inorganic inhibitors to control the corrosion of steel in a 3.5 wt.% NaCl environment. The corrosion measurements were conducted in the 3.5 wt.% NaCl environment by EIS and polarization methods. Surface studies were done by SEM, Raman, GIXRD, and EDS methods. Corrosion studies (EIS and polarization) have revealed that when 500 ppm of Ce(NO3)3 and 500 ppm of TSP are added to the 3.5 wt.% NaCl medium, the highest synergism index (1.27) and inhibition efficiency (73.7%) are achieved. Also, by adding 500Ce-500TPS to the solution, icorr and Rct of steel decreased by about 80% and increased approximately 4-fold, respectively. This improvement in the steel performance against corrosion in the presence of an equal ratio of Ce(NO3)3 and TSP is the outcome of the formation of a hydrophobic dense film (consisting of Ce(OH)3, Ce/Fe-phosphate complexes) on the metal surface. This claim has been proven by SEM/EDS, contact angel, FT-IR, and XRD analysis.

Investigation of Hexylamine Adsorption on Gold in Perchloric Acid

The adsorption of hexylamine at the solution–gold interface in 1 M HClO4 in the presence of 0.1 M Fe2+ and 0.1 Fe3+ was studied by potentiodynamic, chronoamperometric and EIS methods. The main kinetic characteristics of the oxidation-reduction reaction iron ions (exchange current density, transfer coefficient, diffusion coefficients of iron ions) were determined. It was shown that the physical adsorption of hexylamine on gold can be described by the Dhar–Flory–Huggins isotherm. The values of the adsorption constant and the Gibbs free adsorption energy were obtained. A comparison of the free adsorption energy at these interfaces with the interaction energies of hexylamine and water molecules, and hexylamine molecules with each other was carried out. It was shown that hexylamine adsorption at all of these interfaces is due mainly to the hydrophobic effect of the interaction of hexylamine and water molecules.

Investigation of corrosive and mechanical behaviour of Ni-P doped coating by utilizing electroless method

Corrosion is a major concern for steel structures, requiring significant investments for corrosion resistance. This study focused on applying Ni-P and Ni-P with surfactant electroless coatings to TMT steel rebar. The deposition rate of the electroless bath was investigated at different stirrer rotation speeds, with 300 rpm identified as optimal. Morphological and structural analyses were conducted using FESEM and XRD techniques. The average coating thickness reached 131.47 µm at 300 rpm. The addition of admixtures like lactic acid, succinic acid, and citric acid improved coating efficiency. The corrosion behavior of TMT rebar with Ni-P coating and Ni-P with surfactants was examined using EIS and polarization methods. Corrosion current densities were measured as 3.82µA cm-2, 3.91µA cm-2, and 4.1µA cm-2 for TMT steel, Ni-P coated, and Ni-P with surfactant-coated rebars, respectively.

Experimental and computational exploration of synergistic effect of Laurus nobilis extract:Zinc cation on mild steel corrosion inhibition in saline solution

According to the literature, the effectiveness of green corrosion inhibitors in chloride-containing solutions is not acceptable. To improve the anti-corrosion efficiency, a mixture of metal cations and green corrosion inhibitors can be used. In the current study, the synergistic corrosion mitigation effect of Laurus nobilis (LN) extract: Zn mixture on the mild steel (MS) in 3.5% NaCl solution was comprehensively studied by aiding various electrochemical and morphological techniques, as well as molecular-electronic scale modeling approaches (Molecular Dynamics coupled with Monte Carlo, and DFT). The observations from the EIS and polarization methods confirmed 90% inhibition degree using 200–600 ppm LN:Zn mixture along with mixed protection mechanism. Also, EIS results displayed maximum corrosion resistance achievement in the presence of 200–600 ppm LN:Zn mixture (about 10,000 Ω cm2 at 24 h of immersion). The MS surface characterizations via FE-SEM (equipped with EDS) technique disclosed the production of a smooth protective film composed of the LN molecules, Zn oxide/hydroxide species as well as LN/Zn chelation. Additionally, the outcome of the contact angle (CA) analysis clarified the hydrophilic nature of the sample surface protected by LN:Zn mixtures. FT-IR and UV–Visible analyses illustrated the successful LN molecules and Zn cations adsorption over the metal surface. The detailed findings proposed by computational studies (Molecular Dynamics (MD), Monte Carlo (MC), and Density Functional Theory (DFT)) revealed that the LN:Zn+2 complexes interfacially adsorbed onto the metal-based adsorbents through local/global atomic regions, further affirming their strong anti-corrosion propensity.

Glassy Carbon Electrode Modified with CB/TiO2 Layer for Sensitive Determination of Sumatriptan by Means of Voltammetry and Flow Injection Analysis

Sumatriptan is an organic chemical compound from the tryptamine group. It is used as a medicine for migraine attacks and in the treatment of cluster headaches. In this work, a new voltammetric method is proposed for highly sensitive SUM determination, using glassy carbon electrodes modified with carbon black and titanium dioxide suspension. The novelty of the presented work is the usage of the mixture of carbon black and TiO2 as glassy carbon electrode modifier for the first time for SUM determination. The mentioned sensor was characterized by great repeatability and sensitivity of measurements, which resulted in the obtention of a wide range of linearity and a low detection limit. The electrochemical properties of the CB-TiO2/GC sensor was characterized using the LSV and EIS method. The effect of different factors on the SUM peak, such as supporting electrolyte type, preconcentration time and potential, or influence of interferents, were tested using the square wave voltammetry technique. The linear voltammetric response for the analyte was obtained in the concentration range of 5 nmol L−1 to 150 μmol L−1 with a detection limit of 2.9 nmol L−1 for a preconcentration time of 150 s in the 0.1 mol L−1 phosphate buffer pH 6.0. The proposed method was successfully applied for highly sensitive sumatriptan determination in complex matrices, such as tablets, urine, and plasma, with a good recovery parameter (94–105%). The presented CB-TiO2/GC electrode is characterized by great stability, it was used for 6 weeks without significant changes in the SUM peak current. Amperometric and voltammetric measurements of SUM under the flow injection conditions were also performed to indicate the possibility of its fast and accurate determination with a time of single analysis of approx. 30 s.

Electrochemical Activation and NAP-XPS As Well As EIS Characterization of La0.31Sr0.58Ti0.97Ni0.03O3-δ Thin Film Electrode

To improve catalytic activity of LaxSr0.9-xTiyM1-yO3-δ, La1-xSrxCryM1-yO3-δ based materials, doping of perovskite B-site with metals (M) like Ni, Co, Mo or Cu has been proposed. It has been demonstrated, that at elevated temperatures and in reducing atmosphere these dopants exsolve to perovskite surface and form nanometer scale catalyst particles. Exsolution process could be accelerated by using electrochemical polarization. In the present study thin film La0.31Sr0.58Ti0.97Ni0.03O3-δ electrodes was prepared using pulsed laser deposition (PLD) technique. Current collectors were made from Pt (using magnetron sputtering) and placed under the thin film electrode layer. Electrodes were characterized using XPS and EIS method at near ambient pressure conditions (1-5 mbar) at 650 °C, activated electrochemically and characterized again to see the effect of activation. Changes on the electrochemical performance as well as on XPS data caused by electrochemical activation were observed and analyzed.

Y3+ doping and electrochemical properties of LiFe0.5Mn0.5PO4@C cathode material for lithium-ion batteries

LiFe0.5Mn0.5−xYxPO4@C (x = 0, 0.005, 0.01, 0.02, and 0.03) cathode materials were synthesized by a carbothermal solid-state reaction method, and the microstructure and the surface morphology were investigated by XRD, XPS, TEM and SEM technologies. The results show that Y3+ ions are successfully doped into the olivine structure, leading to cell volume shrinkage and an amorphous carbon coating on the particle surface, while the size and dispersion of the particles are also improved. The electrochemical properties of the preferred LiFe0.5Mn0.49Y0.01PO4@C sample were measured by galvanostatic charge-discharge, CV, EIS and GITT methods. The results show that Y3+ doping can significantly decrease its potential polarization, promotes the reduction kinetics of Mn3+ ions and effectively enhances the Li+ diffusion coefficient at 4.1 V. It can provide a discharge specific capacity of 160 mAh g−1 at 0.1 C with an initial coulombic efficiency of 90.1%, 122.93 mAh g−1 at 1 C with a capacity retention of 87.74% after 300 cycles, and 44.89 mAh g−1 at 10 C.

EIS and LEIS Study on In Vitro Corrosion Resistance of Anodic Oxide Nanotubes on Ti–13Zr–13Nb Alloy in Saline Solution

This work concerns the search for new ways to modify the surface of the biomedical Ti–13Zr–13Nb alloy for applications in regenerative medicine and personalized medicine. Obtained for the first time, oxide nanotubes (ONTs) layers of first-generation (1G) on a Ti–13Zr–13Nb alloy were produced by anodizing in 0.5% HF electrolyte at 20 V for 120 min. The physico-chemical characterization of the obtained bamboo-inspired 1G ONTs was conducted using TEM and ATR-FTIR methods. In vitro corrosion resistance of the 1G ONTs and comparative Ti–13Zr–13Nb substrate in saline solution at 37 °C was conducted by open-circuit potential, Tafel curves, anodic polarization curves, and EIS methods. LEIS and SVET study of local corrosion resistance was also carried out. It was found that surface modification by anodizing of the Ti–13Zr–13Nb alloy under proposed conditions allowed to obtain porous ONTs highly resistant to pitting corrosion. The obtained results give a new insight into the relationship between the morphological parameters of first-generation oxide nanotubes and in vitro corrosion resistance of the Ti–13Zr–13Nb alloy in saline solution at the macro- and microscale.

Recrystallization effect on mechanical parameters and increasing of Ag+ ionic conductivity in Ag7(Si1-xGex)S5I ceramic materials

This paper presents the preparation and investigation of Ag7(Si1-xGex)S5I (х = 0.2; 0.4; 0.6; 0.8) ceramic materials. Powder patterns of Ag7(Si1-xGex)S5I indicate the formation of a continuous series of solid solutions with the F-43m cubic cell. Ag7(Si1-xGex)S5I ceramic discs with a porosity of 10 ± 1% were obtained by cold pressing followed by annealing at 700°С. Fabricated ceramics were studied by the SEM, EDS, EIS methods and microhardness measurement. The obtained ceramics are characterized by chemical homogeneity and close values of the average crystallite size in the range of 2.52–2.70 μm. Frequency and temperature dependences of electrical conductivity were analyzed by Nyquist plots. The compositional behavior of ionic conductivity is non-linear and is characterized by a conductivity maximum (8.10 × 10−2 S/cm) at x = 0.6. The temperature dependence of the ionic component obeys to Arrhenius law. The influence of the recrystallization process on the electrical parameters of Ag7(Si1-xGex)S5I solid solution microceramics is discussed.

Sensitive detection of PARP-1 activity by electrochemical impedance spectroscopy based on biomineralization

Poly(ADP)ribose polymerase-1 (PARP-1) has attracted much attention as a tumor marker in recent years. Based on the large negative charge and hyperbranched structure of PARP-1 amplified products (PAR), many detection methods have been established. Herein, we proposed a label-free electrochemical impedance detection method based on the large amount of phosphate groups (PO43−) on the surface of PAR. Although EIS method has high sensitivity, it is not sensitive enough to discern PAR effectively. Therefore, biomineralization was incorporated to increase the resistance value (Rct) distinctly because of the poor electrical conductivity of CaP. During biomineralization process, plentiful Ca2+ was captured by PO43− of PAR through electrostatic interaction, resulting in an increasing Rct of modified ITO electrode. In contrast, when PRAP-1 was absent, only a little Ca2+ was adsorbed on the phosphate backbone of the activating dsDNA. As a result, the biomineralization effect was slight and only a negligible Rct change occurred. Experiment results showed that Rct was associated closely with the activity of PARP-1. There was a linear correlation between them when the activity value was in the range of 0.005–1.0 U. The calculated detection limit was 0.003 U. Results of real samples detection and the recovery experiments were satisfactory, indicating the method has an excellent application prospect.

Simulated EIS and Trukhan model to study the ion transport parameters associated with Li+ ion dynamics in CS based polymer blends inserted with lithium nitrate salt

In the current work electrical and ion transport parameters of polymer electrolyte (PE) system of chitosan (Ch)/poly(2-oxazoline) (POZ)loaded with various concentrations of lithium nitrate (LiNO3) salt were studied. The EIS analysis shows that the load of LiNO3 improves the conductivity of the PE. The depressed semicircle of EIS which its center is below the Zr-axis and the distribution of relaxation time (τ) of the electrolytes verify the non-Debye behavior of the electrolytes. The maximum conducting system (CSPZLI5) shows the highest conductivity of 1.46 × 10−3 S/cm. Transport parameters (number density (n), mobility (μ), viscosity (η), and diffusion coefficient (D) of ions) are measured by Trukhan and EIS methods and compared agreeably and it is also consistent with the conductivity results. The determined n value from EIS was found to increase from 1.69 × 1016cm−3 to 9.5 × 1019 cm−3. Distinguished areas of stability attributed to DC involvement were marked from AC spectra. Dielectric parameters (i.e. ε' and ε'') are high at the low-frequency (fr) window due to electrode polarization (EP). The loss tangent (tan δ) is used to measure the relaxation time (τ) and ion transport parameters. The τ for the PEs is set off to decrease with increase of LiNO3 amount. The minimum τ of 4.08 × 10−7 s confirms the LiNO3 role in increasing ion migration. The transport parameters (n, μ, D, and η) are also in relationship with the dielectric and impedance analyses. From electric modulus examination it is found that the EP contribution can be minimized and relaxation attributing to bulk effects can be highlighted.

Structure and properties of the TiN/ZnO coating obtained by the hybrid method combining PVD and ALD technologies on austenitic Cr-Ni-Mo steel substrate

TiN/ZnO hybrid coatings (combining PVD and ALD technologies) were applied on an AISI 316L steel substrate in the work presented here. For the ALD process, the number of cycles was changed to 500, 1000, and 1500, respectively. This work qualitative analysis using a scanning electron microscope, SEM, elemental analysis using an EDS spectrometer, and morphology studies using an atomic force microscope, AFM. Furthermore, mechanical properties including adhesion, abrasive wear resistance, and roughness were also investigated. Adhesion tests revealed the presence of fine cracks in the TiN/ZnO coating (number of ALD cycles 500) and no delamination. Corrosion tests were conducted in Ringer's solution simulating human body fluids by potentiodynamic and EIS methods. The Pe corrosion protection effectiveness of the tested coatings ranges from 86% to 48%. The hybrid TiN/ZnO hybrid coating produced by the PVD and ALD processes was shown to cause a significant increase in the corrosion resistance of samples made of 316L stainless steel.

Determination of the Dielectric Constant of Niobium Oxide by Using Combined EIS and Ellipsometric Methods.

Combining ellipsometric and EIS methods, the dielectric constant ε for the oxide Nb2O5 at room temperature was determined. At first, the linear dependence between anodization voltage and oxide thickness was established in the form d = 2.14 (± 0.05) · U + 12.2 (± 1.7) nm in the range of anodizing potentials 0-50 V. Next, assuming the equivalent circuit corresponds to one, the capacitance C of the dense oxide layer was measured. All results taken together gave the value of dielectric constant ε = 93 ± 5.

Synthesis of 2-Aryloxy-2,4,4,6,6-pentachlorocyclotriphosphazenes (N3P3Cl5(OAr)): Monoaryloxylatioin of Hexachlorocyclotriphosphazene (N3P3Cl6) and Mass Spectra of Chlorocyclotriphosphazene Derivatives. Difference between EI vs. ESI Methods

Synthesis of 2-Aryloxy-2,4,4,6,6-pentachlorocyclotriphosphazenes (N3P3Cl5(OAr)): Monoaryloxylatioin of Hexachlorocyclotriphosphazene (N3P3Cl6) and Mass Spectra of Chlorocyclotriphosphazene Derivatives. Difference between EI vs. ESI Methods

A facile one-step electrosynthesis of polypyrrole/nano-SbOx composite for supercapacitors

The study depicts a one-step electrochemical synthesis of composite based on polypyrrole (PPy) and SbOx (Sb2O3, Sb2O5) on the graphite surface for the supercapacitor electrode in an acetonitrile solution including pyrrole monomer and Sb(BF4)3. PPy/SbOx composite on graphite plate is characterized using XPS, XRD, TEM, BET, and FESEM by comparing it with PPy homopolymer prepared in the same way. SbOx forms in nano-size and homogeneously encapsulates in PPy due to their simultaneous synthesis. The average pore size of the composite coating is 23.9 nm. The coated PG electrodes are tested in an H2SO4 electrolyte using CV, EIS, and GCD methods. SbOx nanoparticles enhance the capacitive performance of PPy due to the contribution of its catalytic and pseudocapacitive properties. The specific capacitance of the PPy/SbOx-coated PG electrode is 389.5 F g−1 at 5 A g−1 for 1.0 mg cm−2 loading. PPy/SbOx is synthesized in the presence of carboxymethyl cellulose (CMC) to provide stability to the coating. An asymmetric supercapacitor cell is fabricated by assembling the PPy/SbOx/CMC-coated and activated carbon-based graphite paper electrodes (10 mg cm−2 loading). While the potential window expands to 1.4 V, it delivers an energy density of 8.3 Wh kg−1, a power density of 3.5 kW kg−1, and a coulombic efficiency of 90% at 5 A g−1. Post-mortem analysis reveals that structural degradation of PPy in the composite limits long-term stability.

Research on electrochemical characteristics and heat generating properties of power battery based on multi-time scales

A comprehensive understanding of the mechanisms of battery is essential for the design of thermal management systems. In this work, a second-order equivalent circuit model considering the hysteresis effect of the battery was developed, and a combined EIS and HPPC characterization method was used for parameter identification. The results showed that the combining EIS and HPPC parameter measurement methods could extract and analyze the parameters of the battery with different time scales and improve the accuracy of the model. It was found that the polarization internal resistance (R1 and R2) of the battery shows a stronger temperature dependence than the ohmic internal resistance at low temperatures, with R1 being about 170 times higher at low temperatures (10 °C) than high temperatures (50 °C). At the same temperature, τ2 was approximately 100 times larger than τ1, which was two orders of magnitude difference between τ1 and τ2. In addition, the dynamic heat generation results showed that the heat generation rate of the battery increases with decreasing temperature. At 3C discharge rate, the heat generation rate of the battery at low temperature (−10 °C) was about 1.5 times higher than at room temperature (25 °C).

Clarification of the dispersion mechanism of three typical chemical dispersants in lithium-ion battery (LIB) slurry

This paper mainly clarified the dispersion mechanism of three typical chemical dispersants which are polyethylene glycol octylphenyl ether (Triton X-100, T-100), polyethylene pyrrolidone (PVP) and carboxymethyl cellulose (CMC) within lithium-ion battery (LIB) slurry. Initially, the optimum amounts of T-100, PVP and CMC are selected from 0%, 0.5%, 1.5% and 2.5% by evaluating the impedance of LIB slurry in the case of adding each typical chemical dispersant with EIS method. Moreover, the impedance spectrum of three different slurry samples which are PVDF-NMP solution, LiCoO2 slurry and Carbon Black (CB) slurry with the optimum amount of each dispersant are also investigated. After using SEM and C element distribution images of LIB slurry to verify the correctness of the dispersion mechanism of each dispersant, it is concluded that the dispersion CMC with its optimum amount 1.5% is the best one to promote the formation of conductive paths and CB-coated LiCoO2 network structure within LIB slurry, which has the considerably potential to improve the performance of LIB.

Corrosion Inhibition studies of poly (N-tert-amylacrylamide -co- N-phenyl acrylamide) copolymers by EIS and PDP methods

Herein, we reported the synthesis and corrosion inhibition studies of poly (N-tert- amylacrylamide-co- N-phenyl acrylamide) copolymers. The copolymers are synthesized by free radical polymerization using NTA and NPAM monomers . The synthesized copolymers are subjected to corrosion inhibition behavior by EIS and PDP methods. Both the methods showed same results of 85.0 percentage of inhibition

Benzotiyofen@Pd as an efficient and stable catalyst for the electrocatalytic oxidation of hydrazine

• New organic molecule was synthesized and investigated its anode catalyst performance. • CV, CA, and EIS methods are used to determination of the hydrazine oxidation activities. • The specific activity of organic catalyst is found as 25.811 mA/cm 2 . • Pd metal is electrochemically deposited on the organic catalyst, the catalytic activity increased the 80.930 mA/cm 2 . • This activity is higher than the current expensive metal anode catalyst. An efficient methods for the synthesis of 2-(2,5-dimethylphenyl)-3-iodobenzo[ b ]thiophene ( 4 ) is described, and investigated its anode catalyst performance by using electrochemical methods (CV, CA and EIS). When 2-(2,5-dimethylphenyl)-3-iodobenzo[ b ]thiophene ( 4 ) is applied, the specific activity is found as 25.811 mA/cm 2 . Interestingly, when Palladium (Pd) is electrochemically deposited on the benzothiophene derivative, the catalytic activity increased the 80.930 mA/cm 2 . This result is highest than the current metal based anode catalyst. Moreover, EIS and CA measurements display that Pd doped benzothiophene organic catalyst have high stability, and give the low charge transfer resistance. Energy dispersive X-ray (SEM-EDX), electron microscopy, TEM are used for the determination of its surface morphology. As a result, 2-(2,5-dimethylphenyl)-3-iodobenzo[ b ]thiophene ( 4 ) may be alternative electro-catalysts in fuel cell applications.

Proton-Ion Conductivity in Hexagonal Wurtzite-Nanostructured ZnO Particles When Exposed to a Reducing Atmosphere

Zinc oxide (ZnO), a direct wide band gap semiconductor (≥3.30 eV), has widespread potential for applications in energy devices and related industries. The initial physical demonstration of ZnO in ceramic fuel cells (CFCs) gave a new view of developing high ionic conductivity for multifunctional semiconductor technology. However, in the present work, we successfully synthesized highly textured nanoparticles of ZnO using a hydrothermal method followed by sintering in a reducing atmosphere. The resultant ZnO materials as electrolytes showed efficient ionic conductivity (5.28 × 10−2 S cm−1) and an excellent power density of 520 mW cm−2 ± 5% at 550 °C for low-temperature ceramic fuel cells (LT-CFCs). The achievement of enhanced ionic conductivity without any external ions or cation doping in the CFC was anticipated, since there was a rare possibility of vacancies in the bulk ZnO structure to conduct oxygen ions or protons. Therefore, we found that laterally the surfaces of the ZnO nanoparticles could be textured to become oxygen-deficient when sintered in an H2 atmosphere, which suggests a special mechanism for effective ionic transport. Furthermore, experimental analyses such as SEM, XPS, UV–visible, and EIS methods were performed to analyze the changes in the structural properties and mechanism of ionic transport in ZnO nanoparticles. The presented work provides insights into a novel approach for developing high ionic conductivity in electrolytes in low-cost semiconductor oxides such as ZnO for energy storage and conversion devices.