FD simulations of the CV response require input of the diffusivities (D) of the various species. D for C2O4 2-in an aqueous 0.1 M K2SO4 solution was reported by Compton and coworkers to be 1.03 x 10 -5 cm 2 /s. The same value was assumed for C2O4 •-. The diffusivity of CO2 has been measured from CO2 reduction at a Hg electrode in a DMF solution by Savéant and coworkers and reported to be 2.2 x 10 -5 cm 2 /s. This value was adjusted to 2.5 x 10 -6 cm 2 /s using the Stokes-Einstein equation and the dynamic viscosities (𝜂) of H2O and DMF (see Supporting