the anodic peak and the cathodic peak are shied to higher voltage and lower voltage with increasing scan rates, respectively in CV during the measurement on potentiostat. Why ??
The curent you measure îs limited by the diffusion rate and also by the redox reacțion rates. În your case, at higher scanning rate you observe that the reacțion rate îs not high enough to to instantly deplete the concentrațion near the electrode (a higher potențial îs needed).
The CV is diffusion-limited or kinetically limited. in a diffusion-controlled process, the positions of peak voltage do not alter as a function of voltage scan rate. However, if the reaction is kinetically-controlled then voltage peaks alter with increased scan rates, revealing a quasi-reversible reaction for different values of the reduction and oxidation rate constants since the equilibrium at the surface is no longer establishing so rapidly at high scan rates, yet half-wave potential (E1/2) is independent of sweep rate.
an IR drop would also produce the same effect. If your potentiostat has IR compensation, you can reduce this effect.
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