readme_experimental_protocol.md

About

Here I provided a short-guide of experimental acquisition data. I summarized the main things you need to take into account but gcarrascohuertas is not responsible for the bad use of this guide and its consequences over materials and people involved. Please, be careful and document all steps you perform.

Electrochemical setup

First you need following materials in order to perform experiments:

• Three-electrode cell

  • Platinum mesh as counter electrode (CE)). Here I used a Planium mesh from Goodfellow
  • Ag/AgCl as reference electrode (RE). Here I used a Ag/AgCl/KCl (3 M)
  • Your working electrode (WE). Here I used a a polished Glassy carbon electrode (GC, 3 mm diameter, Geometric area 0.0706 cm², BASI).

• Electrolyte

  • K₄[Fe(CN)₆] 0.004 M (0.000004 mol/cm³) dissolved in 0.1 M KCl (D = 7.6E−6 cm²/s)

Electrochemical technique

Electrochemical techniques performed is cyclic voltammograms with a staircase profile (CV). Parameters:

• Start potential : 0.69 V.
• Upper vertex potential: 0.7 V.
• Lower vertex potential: -0.1 V.
• Stop potential: 0.69 V.
• Number of scans: 4.
• Step: 0.002 V.
• Scan rates: 5 mV/seg , 10 mV/seg , 20 mV/seg , 40 mV/seg , 60 mV/seg.

Data treatment. Randles–Ševčík Analysis

Before you obtain results from data read this website for undestand Randles–Ševčík analysis:

https://en.wikipedia.org/wiki/Randles%E2%80%93Sevcik_equation

Also, you need to know which kind of system (reversible or pseudoreversible) do you have depending on your peak separation for your lowest scan rate values.

Data treatment. Randles–Ševčík parameters

Once you understand this analysis. Following parameters were applied as Randles–Ševčík equation parameters:

• Faraday constant: 96485.33289 mol^-1
• Diffusion coeficient for K₄[Fe(CN)₆] 0.0000073 cm²/s
• Concentration of K₄[Fe(CN)₆] 0.000004 mol/cm³
• Gas constant 8.3144598 J mol^-1 K^-1
• Temperature 298 K

Experimental PStrace software routine

Once you finish setting-up all the electrochemical cell components. Create experimental sequence with the parameteres displayed in the screenshots attached in this project.

WARNING: Due to PStrace (PalmSens) software is licensed I can not upload sequence (.psmethod file). If you want PStrace (PalmSens) software sequence for ECSA measurements (.psmethod files) do no hesitate to contact me at : [email protected]

Bibliography

A Practical Beginner’s Guide to Cyclic Voltammetry. Noémie Elgrishi, Kelley J. Rountree, Brian D. McCarthy, Eric S. Rountree, Thomas T. Eisenhart, and Jillian L. Dempsey Journal of Chemical Education 2018 95 (2), 197-206. DOI: 10.1021/acs.jchemed.7b00361