Question

For a cyclic voltammetry experiment illustrating cell potentials of copper complexes:

1) Why did you scan from positive to negative voltage instead of negative to positive?

2) Elaborate on how altering the scan rate affects the voltammogram.

Answer 1

1.in  cyclic voltammetry, initial scanning direction could have a significant effect, especially in irreversible systems, or in systems that can undergo both reduction and oxidation of the starting material.  Where you begin the scan and in which direction you scan first will affect the redox chemistry of the electroactive species at the electrode surface.

its better to start in an uncharged state, then we can scan that electrode in the direction that should charge the capacitor. For instance, if you charge it by treating this electrode material as an anode (+ terminal during charging) then your CV should start by scanning in the positive direction.

2.The potential separation between cathodic and anodic peak does not change by altering the scan rate for reversible processes and increases by increasing the scan rate in irreversible processes