An
accurate measure of the electrochemically active surface area
(ECSA) of an electrode is necessary to quantify electrocatalytic activity.
Herein, we develop a method to deconvolute experimental cyclic voltammograms
measured on platinum electrodes which predominately contain 111 terraces
with 110 and 100 steps. We define simple functions that can be fit
to experimental data to represent various contributions to the total
voltammogram, including hydrogen adsorption on 111 terraces and competitive
hydrogen and hydroxide adsorption on 110 and on 100 steps. We use
our prior density functional theory insight to accurately calculate
the ECSA and the proportion of 111, 100, and 110 sites. We validate
this method for experimental cyclic voltammograms measured on single-crystal
stepped platinum surfaces (with 111 terraces), where the surface area
is known, then extend to polycrystalline and nanoparticle platinum
electrodes.