In cyclic voltammograms (like the one in the attached image) what exactly is the horizontal axis' voltage refering to? Is it the measured voltage between the reference electrode and working electrode? If so, and assuming the measurements are made with a standard voltmeter, which electrode is considered the cathode and which is considered the anode (as in, which is attached to the positive lead and which is attached to the negative lead)?

I was also wondering if these voltages would represent standard electrode potentials or would that depend on the conditions of the data collection

cyclic voltammogram example

  • $\begingroup$ The best is to review the context of the chart in the original source, as we can just guess. $\endgroup$ – Poutnik Apr 30 at 8:37
  • $\begingroup$ Of course is the potential at which the working electrode is kept at that moment of the swap. What else it could/shall be? The working electrode can be the cathode or anode, depending on the process going on. The voltages are those against your reference, it can be a standard or a quasi standard or whatever, electrode calibrated versus a well known redox system. For the actual values plotted, one can choose ref. and state it. Figures have usually captions, and are rarely appended to vacuum but comes with a text. I do not think this deserves an answer other than this comment. $\endgroup$ – Alchimista Apr 30 at 9:24
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    $\begingroup$ Please look at my potentiostat answer here. The working electrode is clamped at virtual ground, i.e., held to less than a millivolt or so of ground (circuit zero potential reference). A voltmeter would not be attached between the reference and working electrodes! So the abscissa is the potential relevant to the electrochemically active species, i.e, going more positive is the oxidative direction and going more negative is the reductive direction. $\endgroup$ – Ed V Apr 30 at 12:05
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    $\begingroup$ You may find many helpful information in the handy primer «A Practical Beginner’s Guide to Cyclic Voltammetry» by Elgrishi et al. (e.g. experimental set up, IUPAC vs. US convention to plot a CV, etc) in 2018JChemEduc197. It is one of the journal's most read publications and open access / available without institutional subscription. $\endgroup$ – Buttonwood Apr 30 at 16:09

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