scholarly journals Cyclic voltammetry of samarium ions in the molten LiCl-KCl eutectic for diffusion coefficient analysis

2019 ◽  
Author(s):  
Vickram Singh ◽  
Christopher Bruneau ◽  
Dev Chidambaram
Keyword(s):  
Cyclic Voltammetry ◽  
Diffusion Coefficient ◽  
Surface Area ◽  
Electrode Surface ◽  
Measurement Errors ◽  
Current Response ◽  
High Concentration ◽  
Melt Temperature ◽  
Peak Current ◽  
Working Electrode

Cyclic voltammetry (CV) was used to investigate the electrochemical behavior of SmCl3 when it is solvated in the molten LiCl-KCl eutectic at 773 K. An experimental method obtained from the literature was adjusted to produce repeatable current responses attributed to the Sm3+/Sm2+ reaction couple and to determine working electrode surface area. The effect of solvating SmCl3 at high concentration was investigated as it relates to electrochemical reversibility and diffusion coefficient analysis. An electrochemically reversible region was identified using correlations between the current response and the scan rate along with peak current ratio measurements. In these, the reversibility was unaffected by increasing concentration. The correlation between current response and concentration was less linear than expected, suggesting the effects of additional modes of diffusion, solution resistance, and charge transfer kinetics may be contributing more at high concentrations. The measurement errors associated with peak current response, working electrode surface area, and melt temperature were used to estimate the associated uncertainties of the reported diffusion coefficients of Sm3+ in the molten LiCl-KCl eutectic. These diffusion coefficient values were found to be relatively consistent with values for Sm3+ reported in the literature for lower concentrations.

scholarly journals Homogeneous electron-transfer of chlorophyll and its derivative chlorophyllin at gold electrode

2019 ◽  
Vol 7 (1) ◽  
pp. 1-17
Author(s):  
Alhasan H ◽  
Alahmadi N ◽  
Wadhawan J
Keyword(s):  
Electron Transfer ◽  
Cyclic Voltammetry ◽  
Electrode Surface ◽  
Gold Electrode ◽  
Reference Electrode ◽  
Surface Preparation ◽  
Active Species ◽  
Bulk Solution ◽  
Photovoltaic Properties ◽  
Working Electrode

Introduction: Chlorophyll is a light harvesting pigment, which absorbs light in the visible spectrum of sunlight and promotes electron transfer, Chlorophyllin (CHL) is One of the most important derivative molecules of chlorophyll. Nowadays, chlorophyll pigment and its derivatives are utilised in organic photosynthetic solar cells for their desirable photovoltaic properties. Cyclic voltammetry (CV) is an essential technique. It is extensively used to study electroactive species to interpret the intermediates of reactions, supply information about the thermodynamics of oxidation-reduction reactions and elucidate the kinetics of electron transfer reactions. Materials and Methods: Prior to the electrochemical study, the working gold (Au) electrode surface was prepared by immersing it in the various concentrations of chlorophyllin for a period time. The electrolyte was degassed by using N2 for approximately 30 minutes inside a Faraday cage before any electrochemical experiment was performed. A three electrode system was used with, Ag/AgCl as a reference electrode, graphiteas a counter and the working electrode (Au). Results and Discussion: As a route to develop new chemical systems for artificial photosynthesis, this work reports the effectiveness of different parameters in transferring electrons between chlorophyllin (CHL) pigment and the working electrode surface (gold). These parameters such as the adsorption time, the electrolyte nature and concentration and chlorophyllin concentration are investigated. The use of chlorophyllin as a redox mediator is examined, with a gold electrode being employed. The importance of gold electrode surface preparation in determining the mechanism of redox is described, and the environment of adsorption process of the different concentrations of chlorophyllin on the surface of the gold electrode has been elucidated in this study. Conclusiones: The electrochemical method showed that the cyclic voltammetry responses of studied adsorption chlorophyllin pigment on the gold electrode were more efficient. In addition, the redox reaction was successful electrochemically in aqueous solution thanthe organic solution. It was suggested that electrons reduce to the chlorophyllin pigment by adding active species in the bulk solution homogeneous transfer. Finally, detections of chl on spinach leaves using various methods are reported.

scholarly journals Elektroplating Grafena-Polianilina pada Stainless Steel sebagai Elektroda pada Elektrolisis Air untuk Produksi Hidrogen

KOVALEN ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 109-120
Author(s):  
Rahmiani Gani ◽  
Syarifah Rabiatul Adawiah ◽  
Arfiani Nur
Keyword(s):  
Stainless Steel ◽  
Cyclic Voltammetry ◽  
Hydrogen Production ◽  
Reference Electrode ◽  
Water Electrolysis ◽  
Potential Difference ◽  
Peak Current ◽  
Working Electrode ◽  
Average Potential ◽  
Cyclic Voltammetry Method

Hydrogen production by water electrolysis can be optimalized by improve the working electrode. Stainless steel as working electrode was coated with graphene and polyaniline by using cyclic voltammetry method with Ag/AgCl as reference electrode and Pt as counter electrode. Coated electrodes were characterized by SEM-EDS and cyclic voltammetry method. Furthermore, the synthesized electrode was applied for water electrolysis by adding 1- 5 g/L NaHCO3. The characterization data showed that Stainless steel/Graphene-Polyaniline electrode can be synthesized by using cyclic voltammetry. The coating process was conducted at sweeping rate 10 mV/s on voltage -0.2 to 0.8 V for 10 cycles. The voltammograms showed that the highest cathodic peak current of electrolysis obtained at 0.491 mA by addition 2 g NaHCO3 on SS/G-PANi0,5 electrode, and the highest anodic peak current obtained at 0.191 mA by addition 2 g NaHCO3 on SS/G-PANi0,5 electrode. Based on the overpotential data, the smallest average potential difference of H+ adsorption obtained by SS/G-PANi1,0 electrode, and the smallest average potential difference of H+ desorption obtained by SS/G-PANi0,5 electrode. Keywords: Stainless steel, hydrogen production, electroplating, electrocatalyst, electrolysis

Tenacious Mass Transfer Limitations Drive Catalytic Selectivity during Electrochemical Carbon Dioxide Reduction

2019 ◽  
Author(s):  
Kailun Yang ◽  
Recep Kas ◽  
Wilson A. Smith
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Catalyst Layer ◽  
Active Surface ◽  
Active Surface Area ◽  
High Concentration ◽  
Copper Electrodes ◽  
Surface Enhanced ◽  
Local Current

<p>This study evaluated the performance of the commonly used strong buffer electrolytes, i.e. phosphate buffers, during CO<sub>2</sub> electroreduction in neutral pH conditions by using in-situ surface enhanced infrared absorption spectroscopy (SEIRAS). Unfortunately, the buffers break down a lot faster than anticipated which has serious implications on many studies in the literature such as selectivity and kinetic analysis of the electrocatalysts. Increasing electrolyte concentration, surprisingly, did not extend the potential window of the phosphate buffers due to dramatic increase in hydrogen evolution reaction. Even high concentration phosphate buffers (1 M) break down within the potentials (-1 V vs RHE) where hydrocarbons are formed on copper electrodes. We have extended the discussion to high surface area electrodes by evaluating electrodes composed of copper nanowires. We would like highlight that it is not possible to cope with high local current densities on these high surface area electrodes by using high buffer capacity solutions and the CO<sub>2</sub> electrocatalysts are needed to be evaluated by casting thin nanoparticle films onto inert substrates as commonly employed in fuel cell reactions and up to now scarcely employed in CO<sub>2</sub> electroreduction. In addition, we underscore that normalization of the electrocatalytic activity to the electrochemical active surface area is not the ultimate solution due to concentration gradient along the catalyst layer.This will “underestimate” the activity of high surface electrocatalyst and the degree of underestimation will depend on the thickness, porosity and morphology of the catalyst layer. </p> <p> </p>

scholarly journals Cyclic Voltammetric Investigations of Thiazine Dyes on Modified Electrodes

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Amitabha Chakraborty ◽  
Shamsuzzaman Ahamed ◽  
Subrata Pal ◽  
Swapan K. Saha
Keyword(s):  
Diffusion Coefficient ◽  
Modified Electrode ◽  
Glassy Carbon ◽  
Electrochemical Behavior ◽  
Modified Electrodes ◽  
Electron Hopping ◽  
Cyclic Voltammetric ◽  
Peak Current ◽  
Quantitative Characteristics ◽  
Thiazine Dyes

Electrochemical behavior of five progressively alkylated thiazine dyes has been investigated at glassy carbon/montmorillonite and glassy carbon/zeolite electrodes. Quantitative characteristics, associated with the positions of peak potentials (Ea and Ec) and current ratios (ia/ic), are measured with scan rates. The peak current observed in the modified electrodes is dependent on both the porosity and nature and number of sites involved in partitioning the complex into film. The values of diffusion coefficient for different dyes have been calculated from electrochemical data. It is suggested that in clay-modified electrode along with physical diffusion the process of electron hopping seems to be most likely.

scholarly journals Electrochemical Study on MgO as an Additive in Molten Li2CO3-Na2CO3 for Molten Carbonate Fuel Cells

2021 ◽  
Author(s):  
Chan Mi Kim ◽  
In Ui Kim ◽  
S. P. Yoon ◽  
Sung Ki Cho
Keyword(s):  
Diffusion Coefficient ◽  
Fuel Cells ◽  
Electrochemical Impedance ◽  
Oxygen Solubility ◽  
Cyclic Voltammograms ◽  
Cyclic Voltammogram ◽  
Molten Carbonate ◽  
High Concentration ◽  
Electrochemical Response ◽  
Molten Carbonate Fuel Cells

Abstract This study investigates the effect of MgO as an additive in molten Li2CO3-Na2CO3 electrolyte for molten carbonate fuel cells through electrochemical analyses. Addition of MgO (1~5 mol%) increased the electrochemical response in cyclic voltammogram of peroxide in molten Li2CO3-Na2CO3. The diffusion coefficient of peroxide in molten Li2CO3-Na2CO3 containing MgO was determined via the comparison between the peak currents of cyclic voltammograms from microwire electrode and macrowire electrode. The addition of MgO did not impact the diffusion coefficient, indicating that the increase in the electrochemical response with the addition of MgO might be attributed to the increase in the peroxide concentration. The change in peroxide concentration was also confirmed by electrochemical impedance analyses, which exhibited a decrease in the exchange current density. The increase in the concentration of peroxide with the addition of MgO might be associated with the high thermal decomposition constant of MgCO3, implying the high concentration of oxide ion in the molten Li2CO3-Na2CO3. This study suggests that MgO might be an effective additive for increasing the oxygen solubility in the molten Li2CO3-Na2CO3, and subsequently for enhancing the performance of molten carbonate fuel cells.

Preliminary dielectrophoresis study: Manipulation of protein albumin and electrical quantification by using cyclic voltammetry technique

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nur Shahira Abdul Nasir ◽  
Revathy Deivasigamani ◽  
Muhammad Khairulanwar Abdul Rahim ◽  
Siti Nur Ashakirin Mohd Nashruddin ◽  
Azrul Azlan Hamzah ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Design Methodology ◽  
Future Prospect ◽  
Electrochemical Technique ◽  
Polystyrene Particle ◽  
Peak Current ◽  
Content Type ◽  
Screen Printed Carbon Electrode ◽  
A New Technique ◽  
Haemodialysis Treatment

Purpose The purpose of this paper is to visualize protein manipulation using dielectrophoresis (DEP) as a substantial perspective on being an effective protein analysis and biosensor method as DEP is able to be used as a means for manipulation, fractionation, pre-concentration and separation. This research aims to quantify DEP using an electrochemical technique known as cyclic voltammetry (CV), as albumin is non-visible without any fluorescent probe or dye. Design/methodology/approach The principles of DEP were generated by an electric field on tapered DEP microelectrodes. The principle of CV was analysed using different concentrations of albumin on a screen-printed carbon electrode. Using preliminary data from both DEP and CV methods as a future prospect for the integration of both techniques to do electrical quantification of DEP forces. Findings The size of the albumin is known to be 0.027 µm. Engineered polystyrene particle of size 0.05 µm was selected to mimic the DEP actuation of albumin. Positive DEP of the sample engineered polystyrene particle was able to be visualized clearly at 10 MHz supplied with 20 Vpp. However, negative DEP was not able to be visualized because of the limitation of the apparatus. However, albumin was not able to be visualized under the fluorescent microscope because of its translucent properties. Thus, a method of electrical quantification known as the CV technique is used. The detection of bovine serum albumin (BSA) using the CV method is successful. As the concentration of BSA increases, the peak current obtained from the voltammogram decreases. The peak current can be an indicator of DEP response as it correlates to the adsorption of the protein onto the electrodes. The importance of the results from both CV and DEP shows that the integration of both techniques is possible. Originality/value The integration of both methods could give rise to a new technique with precision to be implemented into the dialyzers used in renal haemodialysis treatment for manipulation and sensing of protein albumin.

Technical and Practical Aspects of Invasive Recordings and Brain Stimulation

2018 ◽  
pp. 26-37
Author(s):  
Gholam K. Motamedi ◽  
Jean Gotman ◽  
Ronald P. Lesser
Keyword(s):  
Charge Density ◽  
Surface Area ◽  
Brain Stimulation ◽  
Electrode Surface ◽  
Cortical Stimulation ◽  
Basic Principles ◽  
Depth Electrodes ◽  
Cortical Stimulation Mapping ◽  
Drug Resistant Epilepsy ◽  
Intracranial Electrodes

This chapter discusses the technical and practical issues involved in invasive recording and cortical stimulation mapping in patients with drug-resistant epilepsy. It reviews the way in which EEG signals are generated, circumstances when intracranial electrodes are needed, and how such electrodes operate. It also discusses the basic principles of cortical stimulation mapping and different methods of using intracranial electrodes for stimulation purposes, and relevant concepts involved in the process such as charge density and electrode surface area. It reviews different electrodes used for mapping including subdural surface electrodes and depth electrodes.

Sign in / Sign up

Export Citation Format

Share Document