scholarly journals Formation and reduction of anodic film on polycrystalline Bi electrode in pure methanol solutions

2019 ◽  
Vol 9 (4) ◽  
pp. 223-230
Author(s):  
Anastos George Anastopoulos ◽  
Athanasios A. Papaderakis
Keyword(s):  
Electrochemical Impedance ◽  
Film Formation ◽  
Anodic Film ◽  
Potential Range ◽  
Current Profile ◽  
Electrode Potentials ◽  
Methanol Solutions ◽  
Phase Sensitive ◽  
Pure Methanol ◽  
Gradual Variation

The processes of film formation and reduction of bismuth in pure methanol are phenomenologically studied by means of cyclic, ac voltammetric and electrochemical impedance spectroscopic methods. Film formation takes place under low electrode potentials within the potential range from -0.1 to about 0.2 V vs. Ag|AgCl resulting in the development of Bi(CH3O)ads layer. The scan rate effect on the anodic current profile is interpreted in terms of a gradual variation of uncompensated resistance, accompanying the processes of film formation and reduction. Phase sensitive ac voltammetry measurements suggest leaky insulating character of a thin anodic film in agreement with the results of electrochemical impedance experiments.

scholarly journals Spilanthes acmella Leaves Extract for Corrosion Inhibition in Acid Medium

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 106
Author(s):  
Akbar Ali Samsath Begum ◽  
Raja Mohamed Abdul Vahith ◽  
Vijay Kotra ◽  
Mohammed Rafi Shaik ◽  
Abdelatty Abdelgawad ◽  
...  
Keyword(s):  
Mild Steel ◽  
Corrosion Inhibition ◽  
Active Sites ◽  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Film Formation ◽  
Protective Film ◽  
Surface Protection ◽  
Tafel Polarization ◽  
Spilanthes Acmella

In the present study, the corrosion inhibition effect of Spilanthes acmella aqueous leaves extract (SA-LE) on mild steel was investigated in 1.0 M HCl solution at different temperature using weight loss, Tafel polarization, linear polarization resistance (LPR), and electrochemical impedance (EIS) measurements. Adsorption of inhibitor on the surface of the mild steel obeyed both Langmuir and Temkin adsorption isotherms. The thermodynamic and kinetic parameters were also calculated to determine the mechanism of corrosion inhibition. The inhibition efficiency was found to increase with an increase in the inhibitor concentration i.e., Spilanthes acmella aqueous leaves extract, however, the inhibition efficiency decreased with an increase in the temperature. The phytochemical constituents with functional groups including electronegative hetero atoms such as N, O, and S in the extract adsorbed on the metal surface are found responsible for the effective performance of the inhibitor, which was confirmed by Fourier-transform infrared spectroscopy (FT-IR) and ultraviolet–visible spectroscopic (UV-Vis) studies. Protective film formation against corrosion was confirmed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle studies. The result shows that the leaves extract acts as corrosion inhibitor and is able to promote surface protection by blocking active sites on the metal.

Nature and mechanism of anodic film formation on Cu in alkaline phosphate media

1981 ◽  
Vol 125 (2) ◽  
pp. 321-331 ◽  
Author(s):  
Y.A. El-Tantawy ◽  
F.M. Al-Kharafi ◽  
A. Katrib
Keyword(s):  
Film Formation ◽  
Anodic Film ◽  
Alkaline Phosphate

Ferrous Nitrate–Nickel Oxide (Fe(NO3)2–NiO) Nanospheres Incorporated With Carbon Black and Polyvinylidenefluoride for Supercapacitor Applications

2019 ◽  
Vol 16 (3) ◽  
Author(s):  
Aqib Muzaffar ◽  
Keerthana Muthusamy ◽  
M. Basheer Ahamed
Keyword(s):  
Nickel Oxide ◽  
Specific Capacitance ◽  
Double Layer ◽  
Electrochemical Impedance ◽  
Maximum Efficiency ◽  
Potential Range ◽  
Double Layer Capacitance ◽  
Hydrothermal Route ◽  
Sem Images ◽  
Charge Discharge

Ferrous nitrate/nickel oxide {Fe(NO3)2–NiO} nanocomposite was synthesized via two-step facile hydrothermal route. The nanocomposite exhibits crystalline structure as unveiled by X-ray diffraction (XRD) pattern, while as the scanning electron microscope (SEM) images divulge spherical morphologies for both Fe(NO3)2 as well as NiO nanoparticles differentiating from each other in size. Cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques were used to investigate supercapacitive behavior of the symmetrically fabricated nanocomposite electrode configuration using aqueous KOH as the electrolyte. The CV analyses demonstrate dominant electrical double layer capacitance (EDLC) behavior in the potential range of 0–1 V. From charge–discharge curves, the maximum specific capacitance calculated was 460 F g−1 corresponding to the energy density of 16 W h kg−1 at a high power density of 250 W kg−1. EIS data affiliate well with the CV and GCD results justifying the maximum contribution of specific capacitance due to double layer capacitance. The nanocomposite retained 84% of its original capacitance after 1000 cycles and yielded maximum efficiency of 78%.

scholarly journals Ordered SnO2@C Flake Array as Catalyst Support for Improved Electrocatalytic Activity and Cathode Durability in PEMFCs

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2412
Author(s):  
Zhaoyi Yang ◽  
Ming Chen ◽  
Baizeng Fang ◽  
Gaoyang Liu
Keyword(s):  
Electrochemical Impedance ◽  
Proton Exchange ◽  
Pt Catalyst ◽  
Carbon Paper ◽  
Potential Range ◽  
Active Surface Area ◽  
Reduction Peak ◽  
Electrode Structure ◽  
Positive Interaction ◽  
Supported Pt Catalyst

Pt-SnO2@C-ordered flake array was developed on carbon paper (CP) as an integrated cathode for proton exchange membrane fuel cell through a facile hydrothermal method. In the integrated cathode, Pt nanoparticles were deposited uniformly with a small particle size on the SnO2@C/CP support. Electrochemical impedance spectroscopy analysis revealed lower impedance in a potential range of 0.3–0.5 V for the ordered electrode structure. An electrochemically active surface area and oxygen reduction peak potential determined by cyclic voltammetry measurement verified the synergistic effect between Pt and SnO2, which enhanced the electrochemical catalytic activity. Besides, compared with the commercial carbon-supported Pt catalyst, the as-developed SnO2@C/CP-supported Pt catalyst demonstrated better stability, most likely due to the positive interaction between SnO2 and the carbon coating layer.

PHOSPHONIC ACID MONOLAYERS FOR CORROSION PROTECTION OF COPPER: EQCM AND EIS INVESTIGATIONS

2019 ◽  
Vol 27 (06) ◽  
pp. 1950166
Author(s):  
AYSEL YURT ◽  
ESRA SOLMAZ
Keyword(s):  
Molecular Structure ◽  
Corrosion Protection ◽  
Phosphonic Acid ◽  
Quantum Chemical ◽  
Electrochemical Impedance ◽  
Film Formation ◽  
Copper Surface ◽  
Chemical Mechanism ◽  
Frequency Change ◽  
Phosphonic Acids

Preparation, characterization and application of protective phosphonic acid monolayers formed by 1-Aminohexyl phosphonic acid (AHP), 1,4-butanediphosphonic acid (BDPA), 1-amino-1,3-dimethylbutyl phosphonic acid (ADBP) on copper surface as anticorrosive self-assembled molecular monolayers (SAMs) have been investigated by atomic force microscopy (AFM) analysis, electrochemical impedance spectroscopy (EIS) and in situ electrochemical quartz crystal microbalance (EQCM) techniques. Film formation and growth were monitored by EQCM and the step-by-step construction of monolayer was investigated through measurement of the frequency change, which corresponds to mass change due to the adsorption of molecules. Observed increase in electrode mass suggests that SAMs formed on copper surface by the adsorption of phosphonic acids. Results clearly demonstrate that adsorbed amounts of phosphonic acids were strongly influenced by immersion time and molecular structure. Quantum chemical calculations were performed by semi-empirical PM6 method, in order to explain the relationship between molecular structure and adsorption mechanism. Quantum chemical parameters of phosphonic acids propound that adsorption of molecules on copper surface has a chemical mechanism. Corrosion protection ability of SAMs against the acidic corrosion of copper has been evaluated in 0.1[Formula: see text]M H2SO4 solution. It was found that phosphonic acid SAMs act as protective barrier and the protection efficiencies increased in the following order: [Formula: see text].

scholarly journals Metal Foam Electrode as a Cathode for Copper Electrowinning

Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 822
Author(s):  
Modestas Vainoris ◽  
Henrikas Cesiulis ◽  
Natalia Tsyntsaru
Keyword(s):  
Metal Foam ◽  
Electrochemical Impedance ◽  
Copper Substrate ◽  
Double Electric Layer ◽  
Charge Transfer Resistance ◽  
Copper Deposition ◽  
Potential Range ◽  
Flat Plates ◽  
Transfer Resistance ◽  
Plate Electrode

The geometry of porous materials is complex, and the determination of the true surface area is important because it affects current density, how certain reactions will progress, their rates, etc. In this work, we have investigated the dependence of the electrochemical deposition of copper coatings on the geometry of the copper substrate (flat plates or 3D foams). Chronoamperometric measurements show that copper deposition occurs 3 times faster on copper foams than on a flat electrode with the same geometric area in the same potential range, making metal foams great electrodes for electrowinning. Using electrochemical impedance spectroscopy (EIS), the mechanism of copper deposition was determined at various concentrations and potentials, and the capacities of the double electric layer (DL) for both types of electrodes were calculated. The DL capacity on the foam electrodes is up to 14 times higher than that on the plates. From EIS data, it was determined that the charge transfer resistance on the Cu foam electrode is 1.5–1.7 times lower than that on the Cu plate electrode. Therefore, metal foam electrodes are great candidates to be used for processes that are controlled by activation polarization or by the adsorption of intermediate compounds (heterogeneous catalysis) and processes occurring on the entire surface of the electrode.

Sign in / Sign up

Export Citation Format

Share Document