Evaluation of model and dispersion parameters and their effects on the formation of constant-phase elements in equivalent circuits

Flower-like Superhydrophobic Surfaces Fabricated on Stainless Steel as a Barrier against Corrosion in Simulated Acid Rain

Functionalisation of the metal surface of low-carbon ferritic stainless steel (from hydrophilic to hydrophobic properties) was achieved by flower-like hierarchical structures on a steel substrate prepared by a low-cost immersion method. The flower-like structured hydrophobic layers on the steel substrate were obtained by immersing the samples in an ethanolic solution of stearic acid with the addition of various concentrations of expired vitamin E ((+)α-tocopherol). The stability and corrosion-inhibiting effect of the hierarchically structured (such as natural cornflower) hydrophobic layers were studied systematically during short and long immersion tests, 120 h (five days) in an acidic environment (pH = 3) using potentiodynamic measurements, electrochemical impedance spectroscopy and chronopotentiometry. The surfaces of the samples, their wettability, surface morphology and chemical composition were characterised by contact angle measurements, SEM, ATR-FTIR and EDAX. After 120 h of immersion, the inhibition efficiency of the flower-like structured hydrophobic layers on the steel substrate in the selected corrosion medium remained above 99%, and the hierarchical structure (flower-like structure) was also retained on the surface.

Effect of a Magnetic Field on the Electrode Process of Al Electrodeposition in a [Emim]Cl-AlCl3 Ionic Liquid

The magnetohydrodynamic (MHD) effect was usually used to improve the mass transport during electrodeposition in a solution electrolyte. Herein, we reported the effect of a magnetic field on the electrode process of Al electrodeposition in a [Emim]Cl-AlCl₃ ionic liquid composed of pure ions. Under a uniform and perpendicular magnetic field to the Cu electrode plane, electrochemical impedance spectroscopy (EIS) of the circuit, the cyclic voltammetry (CV) curves, and the different capacitances at the potential of zero charge (PZC) were measured, and the electrodeposition of aluminum was carried out at a constant current density. The results indicated that a vertical magnetic field significantly reduced the resistance (activation energy) for charge transfer of electrochemical reduction of Al₂Cl₇^-; meanwhile, the capacitance of an electric double layer (EDL) and the density of the electrodeposited aluminum layer were increased.

Electrochemical DNA Sensor Based on Poly(Azure A) Obtained from the Buffer Saturated with Chloroform

Electropolymerized redox polymers offer broad opportunities in detection of biospecific interactions of DNA. In this work, Azure A was electrochemically polymerized by multiple cycling of the potential in phosphate buffer saturated with chloroform and applied for discrimination of the DNA damage. The influence of organic solvent on electrochemical properties of the coating was quantified and conditions for implementation of DNA in the growing polymer film were assessed using cyclic voltammetry, quartz crystal microbalance, and electrochemical impedance spectroscopy. As shown, both chloroform and DNA affected the morphology of the polymer surface and electropolymerization efficiency. The electrochemical DNA sensor developed made it possible to distinguish native and thermally and chemically damaged DNA by changes in the charge transfer resistance and capacitance.

An investigation on cavitation-corrosion behavior of Ni/β-SiC nanocomposite coatings under ultrasonic field

Ni/β-SiC nanocomposite coating was electroplated on the 17-4 PH SS (precipitation-hardening stainless steel) in modified Watt's bath. The role of cyclic-cavitation (Duty cycle: 50%) on corrosion behavior of Ni/β-SiC nanocomposite coating in 3.5 wt% NaCl solution was investigated using open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The results of OCP tests demonstrated that cavitation led to positive shifts in the potential for Ni composite coating, while it caused the potential negative shifts in the case of 17-4 PH SS. The results of the polarization tests under cavitation condition exhibited positive shifts in potential and an increase in current density up to a specific anodic potential. In higher anodic potentials, the cavitation had a reverse effect on potential and current density. Moreover, it increased the overall corrosion current density. EIS measurements illustrated a severe reduction in electrochemical resistance of both 17-4 PH SS (from 228.15 kΩ.cm² to 14.85 kΩ.cm²) and Ni composite coating (from 20.19 kΩ.cm² to 5.00 kΩ.cm²) after 20 h of the cavitation tests. The cumulative mass loss measurements showed that the mass loss for the substrate (10.3 mg.cm^-2) was about five times more than that of Ni composite coating (2.3 mg.cm^-2). Also, in the coated specimen, the incubation time is increased and the growth slop of the accelerating period decreased under cavitation condition.

Electroanalytical Determination of Cysteine Using the Electrodes Based on Ternary Silver-Copper Sulfides

The amperometric determination of cysteine, using an electrode based on ternary silver-copper sulfide, is presented. Electrochemical characterizations (using cyclic voltammetry) of three electrode materials revealed that the electrode based on the material that consists of jalpaite (Ag₃CuS₂), doped with a small amount of metallic silver, has the best electrocatalytical performance for cysteine oxidation. For the amperometric determination, 0.142 V at pH 5 and 0.04 V at pH 7 vs. Ag/AgCl, related to the electrocatalytical oxidation of thiol group, were chosen. Electrochemical impedance spectroscopy together with Fourier transform infrared spectroscopy (FTIR) revealed that oxidation takes place on the electrode surface with fouling effect, which does not affect a wide linear working range between 1 μM and 100 μM. Sensitivities, at pH 5 and pH 7, are calculated to be 0.11 μA μM-1 and 0.10 μA μM-1, respectively. The detection limits were determined to be 0.036 μM and 0.024 μM for pH 5 and pH 7, respectively. In the presence of uric acid, folic acid, ascorbic acid, and glucose no interference was noticed. This electrode showed remarkable stability and excellent reproducibility. The electrode was exploited for the determination of cysteine in a dietary supplement with the excellent recoveries.

Investigation of myrrh extract as a new corrosion inhibitor for α-brass in 3.5% NaCl solution polluted by 16 ppm sulfide

The performance of extract of myrrh plant as corrosion inhibitor for Cu–Zn alloy in 3.5 wt% NaCl solution polluted by 16 ppm sulfide. The results demonstrated that the corrosion rate of Cu–Zn alloy was decreased in the presence of myrrh extract.

Investigation of the corrosion inhibition of carbon steel in hydrochloric acid solution by using ginger roots extract

The inhibitive effect and adsorption behavior of ginger roots extract (GRE) on the corrosion of carbon steel in 1.0 M HCl solution at different temperatures were investigated.

The role of passive potential in ultrasonic cavitation erosion of titanium in 1 M HCl solution

The influence of the applied passive potential on the ultrasonic cavitation erosion of Ti specimen in 1 M HCl solution was investigated by mass loss experiment, scanning electron microscopy (SEM), electrochemical impedance spectra (EIS) and Mott-Schottky plot. The results showed that Ti was in the passive state within the potential region from -0.3 VSCE to 1.5 VSCE under ultrasonic cavitation erosion. The applied passive potential can obviously decrease the mass loss of Ti caused by ultrasonic cavitation erosion in 1 M HCl solution. The resistance of the passive film increased, the flat band potential moved to positive direction, and the donor density of the passive film decreased with increasing the passive potential. Finally, a physical model was provided to explain the experimental results based on energy band and semi-conductive theories.

Corrosion inhibition of mild steel by an imidazolium ionic liquid compound: the effect of pH and surface pre-corrosion

The corrosion inhibition performance of 1-decyl-3-methylimidazolium chloride (DMICL) on mild steel was investigated in a carbon dioxide-saturated NaCl solution at pH 3.8 and 6.8.

Biomembrane disruption by silica-core nanoparticles: effect of surface functional group measured using a tethered bilayer lipid membrane

Engineered nanomaterials (ENM) have desirable properties that make them well suited for many commercial applications. However, a limited understanding of how ENM's properties influence their molecular interactions with biomembranes hampers efforts to design ENM that are both safe and effective. This paper describes the use of a tethered bilayer lipid membrane (tBLM) to characterize biomembrane disruption by functionalized silica-core nanoparticles. Electrochemical impedance spectroscopy was used to measure the time trajectory of tBLM resistance following nanoparticle exposure. Statistical analysis of parameters from an exponential resistance decay model was then used to quantify and analyze differences between the impedance profiles of nanoparticles that were unfunctionalized, amine-functionalized, or carboxyl-functionalized. All of the nanoparticles triggered a decrease in membrane resistance, indicating nanoparticle-induced disruption of the tBLM. Hierarchical clustering allowed the potency of nanoparticles for reducing tBLM resistance to be ranked in the order amine>carboxyl~bare silica. Dynamic light scattering analysis revealed that tBLM exposure triggered minor coalescence for bare and amine-functionalized silica nanoparticles but not for carboxyl-functionalized silica nanoparticles. These results indicate that the tBLM method can reproducibly characterize ENM-induced biomembrane disruption and can distinguish the BLM-disruption patterns of nanoparticles that are identical except for their surface functional groups. The method provides insight into mechanisms of molecular interaction involving biomembranes and is suitable for miniaturization and automation for high-throughput applications to help assess the health risk of nanomaterial exposure or identify ENM having a desired mode of interaction with biomembranes.