To get a better intuition for 𝜆 and 𝜇 let us look at two cases: First, at 𝜆 = 1 the electron transfer occurs outside of the EDL where also the interactions between the reductant and oxidant systems should be neglectable (Eq. 11a). Except for the explicit appearance of the activities at the formal state, per definition set to unity, Eq. 11b is identical to the B-V equation. This means, that the B-V model does not describe an electron transfer on an electrode, rather an electron transfer in the bulk solution, just outside the EDL.