Reversible vs Irreversible Voltammetry

When analysing a voltammogram it is important to consider whether the electron transfer rate is reversible or irreversible in nature. Discuss the main features of a voltammogram that can be readily used to qualitatively decide whether a voltammogram indicates reversible or irreversible electron transfer. 

Consideration of three main features allows an experimentalist to assess if a voltammogram is exhibiting reversible electron transfer or not. These are as follows  

Further, the peak-to-peak separation for a voltammogram will vary as a function of scan rate for non-reversible electron transfer. The separation will be much larger for the irreversible case. 

Tafel analysis of the voltammetric wave will provide the same information. From Problems 2.3 and 2.4, we know that for a one-electron irreversible wave, Tafel analysis yields a line of gradient equal to aP/RT, whereas for a reversible one-electron wave the gradient is equal to F/RT, such that the exponential portion (Tafel region) of the voltammogram is steeper in the reversible case. 

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