MolDraw › Chemistry tools › Cyclic Voltammetry Viewer
Free Cyclic Voltammetry Viewer
Open cyclic voltammograms, pick a cycle and read Epa, Epc, E½, ΔEp and ipa/ipc in plain words. Convert reference electrodes, estimate HOMO and LUMO, and check diffusion with a scan-rate series. Your files stay on your device.
or drop them here. CSV/TXT, CH Instruments, BioLogic .txt, Gamry .DTA or Autolab ASCII. Pick several files for a scan-rate series.
· Examples are simulated and free to reuse. Download the sample .csv.
Reference and units
0.0707 cm² is a 3 mm diameter disc.
Peaks
HOMO / LUMO from onset potentials
Scan-rate analysis (Randles-Sevcik)
How to use the cyclic voltammetry viewer
- Open your file(s), or press an example button.
- Pick what the data was measured against and what you want to show. Enter your ferrocene E½ if you have it.
- Choose a cycle. Read Epa, Epc, E½, ΔEp and ipa/ipc, and the note under the table.
- For energy levels, open HOMO / LUMO. Tick the onsets you want to use.
- For a scan-rate series, open several files, check each scan rate, then open Scan-rate analysis.
- Export a PNG or CSV.
Reading a cyclic voltammogram
The potential sweeps up and back while the current is recorded. An anodic peak (Epa) shows oxidation and a cathodic peak (Epc) shows reduction. For a reversible one-electron couple, E½ = (Epa + Epc)/2 is close to the formal potential, ΔEp is about 59 mV at 25 °C and ipa/ipc is about 1. A larger ΔEp means slower electron transfer. A missing return peak means the product reacts away.
Peak current grows with √v for diffusing species (Randles-Sevcik) and with v for species fixed on the electrode. For organic semiconductors the onset potentials vs Fc/Fc+ give rough HOMO and LUMO levels.
Frequently asked questions
Is my data uploaded?
No. Files are read and drawn in your browser only.
Which files can I open?
CSV or TXT with potential and current columns (time and cycle columns are optional), CH Instruments text exports, BioLogic EC-Lab .txt exports, Gamry .DTA files and Autolab NOVA ASCII exports. Current units (A, mA, µA, nA) are read from the column header.
How are the peaks and ipa/ipc found?
The first peak is measured from the charging baseline, extended under the peak. The return peak uses Nicholson's method, which allows for the current still decaying from the first peak. ΔEp near 59 mV (one electron, 25 °C) and ipa/ipc near 1 point to a reversible couple.
How do I convert between reference electrodes?
Pick what your data was measured against and what you want to show. The tool uses SCE = +0.241 V, Ag/AgCl (sat. KCl) = +0.197 V and Ag/AgCl (3 M KCl) = +0.210 V vs SHE. For Fc/Fc+, enter the ferrocene E½ you measured in your own cell. Otherwise +0.40 V vs SCE (acetonitrile) is assumed.
How are HOMO and LUMO estimated?
From the onset potentials vs Fc/Fc+: E(HOMO) = −(E ox, onset + 4.8) eV and E(LUMO) = −(E red, onset + 4.8) eV. The 4.8 eV value is a common convention for the Fc/Fc+ level below vacuum. Some papers use 5.1 eV, so you can change it. These are estimates, not exact orbital energies.
What does the Randles-Sevcik analysis tell me?
For a species that diffuses to the electrode, the peak current grows with the square root of the scan rate. The slope of log ip against log v is then about 0.5, and the tool gives the diffusion coefficient D. A slope near 1 means the species is fixed on the surface (adsorbed or a film).