Electrode reactions

Faradays law

  • The amount (moles) of any substance produces or consumed in an electrode reaction is proportional to the quantity of charge passed.
  • Non-faradaic currents:
    • Capacitive currents
    • Electronic conduction
    • Competing reactions

Coulometry

  • Analysis of concentration c\(_i\) of a reactant species \(i\) in a finite volume V at fixed well-selected voltage
  • The total charge converted is Q = -nFVc\(_i\)/\(\nu_i\)
    • n av \(\nu_i\) are te number of electrons and molecules, respectively, involved in the reaction
  • Charge Q is current \(I\) integrated over time t:
  • Flowing coloumetry
    • Limiting current at given flow and fixed voltage.

Butler-Volmer equation

Example:

  • Butler-Volmer:
    • \(k^{\circ}\) is a formal rate constant
    • Positive term says
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