scholarly journals Scanning Electrochemical Microscopy of Electrically Heated Wire Substrates

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1169
Author(s):  
Stefan Wert ◽  
Alexander Fußstetter ◽  
Christian Iffelsberger ◽  
Frank-Michael Matysik
Keyword(s):  
Room Temperature ◽  
Open Circuit Potential ◽  
Scanning Electrochemical Microscopy ◽  
Open Circuit ◽  
Bulk Solution ◽  
Wire Surface ◽  
Competition Mode ◽  
Heated Wire ◽  
The Wire ◽  
Electrochemical Microscopy

We report a new configuration for enhancing the performance of scanning electrochemical microscopy (SECM) via heating of the substrate electrode. A flattened Pt microwire was employed as the substrate electrode. The substrate was heated by an alternating current (AC), resulting in an increased mass transfer between the wire surface and the bulk solution. The electrochemical response of the Pt wire during heating was investigated by means of cyclic voltammetry (CV). The open circuit potential (OCP) of the wire was recorded over time, while varied heating currents were applied to investigate the time needed for establishing steady-state conditions. Diffusion layer studies were carried out by performing probe approach curves (PACs) for various measuring modes of SECM. Finally, imaging studies of a heated substrate electrode surface, applying feedback, substrate generation/tip collection (SG/TC), and the competition mode of SECM, were performed and compared with room temperature results.

Investigation of Ion Transport in Polypyrrole Modified Ultra-Microelectrodes During Scanning Electrochemical Microscopy

2016 ◽  
Author(s):  
Vinithra Venugopal ◽  
Vijay Venkatesh ◽  
Vishnu Baba Sundaresan
Keyword(s):  
Scanning Electrochemical Microscopy ◽  
Redox Mediator ◽  
Electrochemical Measurements ◽  
Bulk Solution ◽  
Electrochemical Technique ◽  
Diffusion Field ◽  
Faradaic Current ◽  
Constant Height ◽  
Electrolyte Bulk ◽  
Electrochemical Microscopy

Scanning electrochemical microscopy (SECM) is an electrochemical technique used to measure faradaic current changes local to the surface of a sample. The incorporation of shear force (SF) feedback in SECM enables the concurrent acquisition of topographical data of substrates along with electrochemical measurements. Contemporary SECM measurements require a redox mediator such as ferrocene methanol (FcMeOH) for electrochemical measurements; however, this could prove detrimental in the imaging of biological cells. In this article, nanoscale polypyrrole membranes doped with dodecylbenzene sulfonate (PPy(DBS)) are deposited at the tip of an ultra-microelectrode (UME) to demonstrate a novel modification of the contemporary SECM-SF imaging technique that operates in the absence of a redox mediator. The effect of distance from an insulating substrate and bulk electrolyte concentration on sensor response are examined to validate this technique as a tool for correlated topographical imaging and cation flux mapping. Varying the distance of the PPy(DBS) tipped probe from the substrate in a solution containing NaCl causes a localized change in cation concentration within the vicinity of the membrane due to hindered diffusion of ions from the bulk solution to the diffusion field. The cation transport into the membrane in close proximity to the substrate is low as compared to that in the electrolyte bulk and asymptotically approaches the bulk value at the sense length. At a constant height from the base, changing the bulk NaCl concentration from 5 mM to 10 mM increases the filling efficiency from 35% to 70%. Further, the sense length of this modified electrode in NaCl is about 440 nm which is significantly lower as compared to that of a bare electrode in ferrocene methanol (5–20 μm). It is postulated that this novel technique will be capable of producing high resolution maps of surface cation concentrations, thus having a significant impact in the field of biological imaging.

Evaluation of Enzymatic Kinetics of GOx-based Electrodes by Scanning Electrochemical Microscopy at Redox Competition Mode

2017 ◽  
Vol 29 (6) ◽  
pp. 1532-1542 ◽  
Author(s):  
Inga Morkvenaite-Vilkonciene ◽  
Almira Ramanaviciene ◽  
Povilas Genys ◽  
Arunas Ramanavicius
Keyword(s):  
Scanning Electrochemical Microscopy ◽  
Enzymatic Kinetics ◽  
Competition Mode ◽  
Kinetics Of ◽  
Electrochemical Microscopy

Aluminium corrosion studies. IV. Pitting corrosion

1978 ◽  
Vol 31 (5) ◽  
pp. 943 ◽  
Author(s):  
RT Lowson
Keyword(s):  
Open Circuit Potential ◽  
Chloride Concentration ◽  
Open Circuit ◽  
Aluminium Chloride ◽  
Bulk Solution ◽  
Pitting Potential ◽  
Functional Relationships ◽  
Corrosion Studies ◽  
Thermodynamic Equilibrium Condition ◽  
Chloride Activity

Measurements are reported for the variation of the open-circuit potential, Er, of aluminium in oxygen-saturated sodium salt solutions. The value of Er was independent of SO42- and NO3- concentrations and similar to the value obtained for water (0.04 (s.h.e.)). Er was a function of chloride concentration given by ������������������� Er = -0.475-0.060log[Cl-] V (s.h.e.) at 25�C. There was a less well defined relationship between Er and NO2-, I- and Br-, and a complex relationship with F-. ��� The potentiodynamic characteristics are reported for aluminium in 1-0.01 mol l-1 Cl- oxygen-saturated solutions. Functional relationships were found for E0, Ep, Es and E0' with chloride activity at 5, 25, 50 and 75°C. Hysteresis effects are reported. ��� The experimental results are interpreted in terms of a thermodynamic equilibrium condition between the surface oxide and soluble aluminium chloride. As the system oscillates across the equilibrium conditions the surface will passivate or pit. A critical bulk solution chloride concentration is necessary to maintain the growth of the pit; the experimental value was 1.6 mol l-1 Cl- and the corresponding open-circuit potential was Ecrit = -0.48 V (s.h.e.). The pitting potential, Ev, was interpreted as an overpotential, ηp, given by η = Ep,- Ep-Ecrit.

Modelling of Scanning Electrochemical Microscopy at Redox Competition Mode Using Diffusion and Reaction Equations

2016 ◽  
Vol 222 ◽  
pp. 347-354 ◽  
Author(s):  
Feliksas Ivanauskas ◽  
Inga Morkvenaite-Vilkonciene ◽  
Rokas Astrauskas ◽  
Arunas Ramanavicius
Keyword(s):  
Scanning Electrochemical Microscopy ◽  
Competition Mode ◽  
Reaction Equations ◽  
Electrochemical Microscopy

scholarly journals SYNTHESIS AND EVALUATION OF ETHYL (4-(N-(THIAZOL-2-YL) SULFAMOYL) PHENYL)CARBAMATE (TSPC) AS A CORROSION INHIBITOR FOR MILD STEEL IN 0.1M HCL

2016 ◽  
Vol 11 (2) ◽  
pp. 3441-3451 ◽  
Author(s):  
A. M. El-Shamy ◽  
M. F. Shehata ◽  
Samir T. Gaballah ◽  
Eman A. Elhefny
Keyword(s):  
Mild Steel ◽  
Corrosion Inhibitor ◽  
Room Temperature ◽  
Open Circuit Potential ◽  
Inhibition Efficiency ◽  
Electrochemical Techniques ◽  
Open Circuit ◽  
Free Energy Of Adsorption ◽  
Langmuir Adsorption ◽  
Gibb’S Free Energy

Laboratory synthesized ethyl (4-(N-(thiazol-2-yl)sulfamoyl)phenyl)carbamate (TSPC), characterized by 1H NMR spectroscopy, was evaluated as corrosion inhibitor of mild steel in 0.1M HCl using electrochemical techniques. Open circuit potential, potentiodynamic polarization and impedance spectroscopy were used to evaluate the inhibition efficiency of (TSPC) at various concentrations. The obtained electrochemical data indicated that (TSPC) acts as moderate corrosion inhibitor for mild steel in acidic media. It is found that the inhibition efficiency increases with the concentration of the inhibitor till 400ppm. The adsorption isotherm involving physisorption of (TSPC) at room temperature and the experimental data complied to the Langmuir adsorption isotherms and the negative values of the Gibb’s free energy of adsorption obtained suggested that inhibitor molecules have been spontaneously adsorbed onto the mild steel surface.

Effect of Viscosity on Steady-State Voltammetry and Scanning Electrochemical Microscopy in Room Temperature Ionic Liquids

2010 ◽  
Vol 114 (13) ◽  
pp. 4442-4450 ◽  
Author(s):  
Kevin R. J. Lovelock ◽  
Frances N. Cowling ◽  
Alasdair W. Taylor ◽  
Peter Licence ◽  
Darren A. Walsh
Keyword(s):  
Ionic Liquids ◽  
Steady State ◽  
Room Temperature ◽  
Scanning Electrochemical Microscopy ◽  
Room Temperature Ionic Liquids ◽  
Electrochemical Microscopy

scholarly journals Characterization of Inherently Chiral Electrosynthesized Oligomeric Films by Voltammetry and Scanning Electrochemical Microscopy (SECM)

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5368
Author(s):  
Margherita Donnici ◽  
Rosanna Toniolo ◽  
Serena Arnaboldi ◽  
Patrizia R. Mussini ◽  
Tiziana Benincori ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Scanning Electrochemical Microscopy ◽  
Redox Mediators ◽  
Feedback Effects ◽  
Au Electrode ◽  
Competition Mode ◽  
Inherently Chiral ◽  
Discriminating Ability ◽  
Electrochemical Microscopy

A voltammetric and scanning electrochemical microscopy (SECM) investigation was performed on an inherently chiral oligomer-coated gold electrode to establish its general properties (i.e., conductivity and topography), as well as its ability to discriminate chiral electroactive probe molecules. The electroactive monomer (S)-2,2′-bis(2,2′-bithiophene-5-yl)-3,3′-bibenzothiophene ((S)-BT2T4) was employed as reagent to electrodeposit, by cyclic voltammetry, the inherently chiral oligomer film of (S)-BT2T4 (oligo-(S)-BT2T4) onto the Au electrode surface (resulting in oligo-(S)-BT2T4-Au). SECM measurements, performed in either feedback or competition mode, using the redox mediators [Fe(CN)6]4− and [Fe(CN)6]3− in aqueous solutions, and ferrocene (Fc), (S)-FcEA, (R)-FcEA and rac-FcEA (FcEA is N,N-dimethyl-1-ferrocenylethylamine) in CH3CN solutions, indicated that the oligomer film, as produced, was uncharged. The use of [Fe(CN)6]3− allowed establishing that the oligomer film behaved as a porous insulating membrane, presenting a rather rough surface. This was inferred from both the approach curves and linear and bidimensional SECM scans, which displayed negative feedback effects. The oligomer film acquired semiconducting or fully conducting properties when the Au electrode was biased at potential more positive than 0.6 V vs. Ag|AgCl|KCl. Under the latter conditions, the approach curves displayed positive feedback effects. SECM measurements, performed in competition mode, allowed verifying the discriminating ability of the oligo-(S)-BT2T4 film towards the (S)-FcEA and (R)-FcEA redox mediators, which confirmed the results obtained by cyclic voltammetry. SECM linear scans indicated that the enantiomeric discriminating ability of the oligo-(S)-BT2T4 was even across its entire surface.

scholarly journals Influence of Ultrasonic Excitation Sealing on the Corrosion Resistance of HVOF-Sprayed Nanostructured WC-CoCr Coatings under Different Corrosive Environments

Coatings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 724 ◽  
Author(s):  
Zhang ◽  
Hong ◽  
Lin ◽  
Zheng
Keyword(s):  
Corrosion Resistance ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Aluminum Phosphate ◽  
Open Circuit ◽  
Corrosive Environments ◽  
Oxygen Fuel

The corrosion behavior of unsealed and sealed high-velocity oxygen-fuel (HVOF)-sprayed nanostructured WC-CoCr cermet coatings under different corrosive environments was investigated using scanning electron microscopy (SEM), open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Ultrasonic excitation sealing with aluminum phosphate was performed in an external ultrasonic bath with the frequency of 40 kHz at atmospheric pressure and room temperature. SEM micrographs revealed that the exposed area of the coating was effectively reduced by the coverage of aluminum phosphate sealant on the majority of pores. Electrochemical measurements demonstrated that the sealant with the help of ultrasonic energy could shift the corrosion potential to a more noble direction, reduce the corrosion current density, increase the resistance of charge transfer, and effectively improve the corrosion resistance of the coating in both 3.5 wt % NaCl and 1 mol·L−1 HCl solutions.

Sign in / Sign up

Export Citation Format

Share Document