Figure illustrates schematically the concentration profiles of the substrate and product for canonical MM mechanism in the real space and can be readily adapted to the more complex mechanisms which will be considered in the following. Since all these species diffuse in the solution their concentration profiles are linear in the appropriate transformed space: 𝜁 = 𝑟 (1 -𝑟 /𝑟) for electrodes of radius 𝑟 equivalent to hemispherical ones or 𝜁 = 𝑟 ln(𝑟/𝑟 ) for cylindrical ones . As shown in Fig. , diffusion can then be modeled through involvement of steady or quasi-steady state diffusion layers of thickness 𝛿 given by: