Experimental corroboration of the theory of chronoamperometry at high roughness electrode for reversible charge transfer

An asymptotic theory for the single potential step chronoamperometry is validated for ferrocene in 1-Butyl-3-methylimidazolium tetrafluoroborate ([bmim] [BF4]) room temperature ionic liquid (RTIL) at nano-particles deposited mesoporous gold wires. The elegance of asymptotic equation arises due to minimal need of (only two) morphological surface characteristics, viz. roughness factor (R*) and width of roughness of mesoporous layer (h). It also accounts for the contribution from unequal diffusion coefficient of electro-active species and uncompensated solution resistance. Theory is also corrected for electric double layer contribution. Mesoporous electrodes are created (with R* >10) over mechanically roughened gold wires by depositing electrochemically synthesized gold nano-particles. Morphological parameters, R* and h, are determined using cyclic voltammetry (CV) and scanning electron microscopy (SEM), viz. CV and SEM method (see S.Dhillon and R.Kant, 2013). Asymptotic equation shows quantitative agreement with the experimental data over a broad time scale (between 0.2 ms and 100 s). Finally, this asymptotic equation can be used for the extraction of statistical roughness along with usual electrochemical quantities.