CVsim

cvsim is a Python package for cyclic voltammogram (CV) simulation via a semi-analytical method developed by Oldham and Myland¹. It is valid for CV experiments performed on disk macroelectrodes, and uses a semi-integration algorithm. In the limit of infinitely small potential steps, this algorithm is an exact solution. Due to the precision of standard potentiostats, simulations that use a potential step of 1-5 mV typically provide a reasonable accuracy-computing time trade-off, where accuracy sanity checks (e.g. Randles-Sevcik relationship for E_r and E_q mechanisms) have been performed.

Currently available mechanisms:

• One-electron process: E_r , E_q , and E_qC
• Two-electron process: E_qE_q and Square scheme

Installation

cvsim can be installed from PyPI using pip:

pip install cvsim

See Getting started with cvsim.py for instructions on simulating CVs.

Dependencies

cvsim requires:

• Python (>=3.10)
• SciPy

Package Structure

• mechanisms.py: Specifies one-/two-electron process mechanisms to be simulated.
• fit_curve.py: Performs fitting of experimental CV data according to a desired mechanism.

Example

To simulate a reversible (Nernstian) CV:

from cvsim.mechanisms import E_rev

potential, current = E_rev(
    start_potential=0.3,       # V vs. reference
    switch_potential=-0.5,     # V vs. reference
    reduction_potential=-0.1,  # V vs. reference
    scan_rate=0.1,             # V/s
    c_bulk=1.0,                # mM (mol/m^3)
    diffusion_reactant=1e-6,   # cm^2/s
    diffusion_product=2e-6,    # cm^2/s
).simulate()

Input Parameters

• E_start/E_switch/E^o' = V vs ref.
• Scanrate = V/s
• Active species concentration = mM (mol/m³)
• Diffusion coefficients = cm²/s

Optional Parameters

• Potential step size = mV
• Disk radius = mm
• Temperature = K

and if needed

• Standard rate constant, k_o = cm/s
• 1^st order chemical rate constants (k_forward, k_backward) = s^-1

[1] Oldham, K. B.; Myland, J. C. Modelling cyclic voltammetry without digital simulation, Electrochimica Acta, 56, 2011, 10612-10625.

*The schemes for CE_r , catalytic C'E_q , and E_rCE_r need development, PRs welcome!

License

MIT