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Thứ Tư, 13 tháng 11, 2024

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https://thongke.cesti.gov.vn/dich-vu-thong-ke/tai-lieu-phan-tich-thong-ke/845-thong-ke-mo-ta-trong-nghien-cuu-dai-luong-do-phan-tan

https://nghiencuugiaoduc.com.vn/bai-7-thong-ke-mo-ta-descriptive-statistics/2/

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Thứ Năm, 7 tháng 11, 2024

Cyclic Voltammetry . Ferro/Ferri

Duck shape:

Duck-shaped cyclic voltammogram of ferrocene 

cyclic voltammogram for ferrocene

Nguồn: Electrochemical Sensing of Oxygen Gas in Ionic Liquids on Screen Printed Electrodes

3. A comparison of cyclic voltammetric wave-shapes for reversible, quasireversible, and irreversible electron transfer process with the same formal potential, E f 0 , on a macrodisk electrode (where planar diffusion dominates). The inset shows the triangular potential "ramp" applied to the working electrode during measurements. 

 More: https://en.wikipedia.org/wiki/Cyclic_voltammetry 


depicts the CV curves of the Fe 2+ /Fe 3+ redox couple using a GC electrode with various scan rates between À0.5 and 1.2 V (vs. Ag/AgCl) at room temperature. The current density was normalized to the geometrical area of the working electrode. As shown in the gure, increasing the scan rate from 10 to 70 mV s À1 results in an increase in the anodic and cathodic peak current densities. Moreover, the anodic peak potential that appears at about 0.68-0.78 V corresponds to the oxidation of Fe 2+ to Fe 3+. The corresponding cathodic peak potential occurs at about 0.23-0.33 V during the reverse scan. The redox peak potential separation related to the redox couple Fe 2+ /Fe 3+ is around 0.4 V, indicating that the Fe 2+ /Fe 3+ redox couple has sufficient reversibility to be used as the positive electrolyte for the proposed redox ow battery system. To determine the potential region of the redox reactions, the CV curves of 1.8 M CuCl in 2.4 M HCl/2.4 M CaCl 2 electrolyte solution were performed using a GC working electrode at different scan rates, as shown in Fig. 3, in which the potential window for Cu + /Cu 0 and Cu 2+ /Cu + was over 1.6 V. As observed, peak (a) displays the oxidation of Cu + to Cu 2+ and peak (b) shows the reduction of Cu 2+ to Cu +. Peak (c) suggests the solid Cu formation on the GC electrode surface on the negative side. The sharp decrease in current indicates the typical nucleation loop related to the Cu metal electrodeposition onto the GC electrode. Once nucleation occurs, no difference is apparent between the various scan rates used. The nal peak (d), suggests the dissolution of Cu 0 that is electrodeposited onto the GC electrode, which oxidizes back to Cu +. To compare the electrochemical activities, a CV test was performed with and without the addition of Bi 2 O 3. Fig. 4 presents the CV curves of the Fe 2+ /Fe 3+ redox couple on a GC working electrode with and without the addition of Bi 3+ at a scan rate of 50 mV s À1. The matching reactions of oxidationreduction couples are marked in the gure. The standard potential of Bi 3+ /Bi 0 (46 mV vs. Ag/AgCl) is detected in the CV  

CV curves of 1.5 M FeCl 2 in a 3 M HCl using GC electrode with and without 0.01 M Bi 3+ at a scan rate of 50 mV s À1 . 

Nguồn: The effect of adding Bi 3+ on the performance of a newly developed iron–copper redox flow battery (DOI:10.1039/C7RA12926B)

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Cyclic voltammetry 

Cyclic voltammetry 

Cyclic voltammetry 

where: Em is midpoint potential, Epa is peak anodic potential,
Epc is peak cathodic potential and E0 is standard reduction potential.

Fig. 2-3-1 Time change of sweep potential.

Fig. 2-3-2 Cyclic voltammetry.

 https://www.als-japan.com/1822.html

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1.- Eaton, W. A.; George, P.; Hanania, G. I. Thermodynamic Aspects of the Potassium Hexacyanoferrate(III)-(II) System. I. Ion Association. J. Phys. Chem. 1967, 71 (7), 2016–2021. https://doi.org/10.1021/j100866a007.
2.- Hanania, G. I.; Irvine, D. H.; Eaton, W. A.; George, P. Thermodynamic Aspects of the Potassium Hexacyanoferrate(III)-(II) System. II. Reduction Potential. J. Phys. Chem. 1967, 71 (7), 2022–2030. https://doi.org/10.1021/j100866a008.

 

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