Open AccessEstimating the Electrochemically Active Area: Revisiting a Basic Concept in Electrochemistry
Author(s) -
Dyovani Coelho,
Giuliana M. Luiz,
Sérgio Antônio Spínola Machado
Publication year - 2021
Publication title -
journal of the brazilian chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.337
H-Index - 70
eISSN - 1678-4790
pISSN - 0103-5053
DOI - 10.21577/0103-5053.20210080
Subject(s) - chronoamperometry , cyclic voltammetry , electrochemistry , monolayer , platinum , electrode , redox , analytical chemistry (journal) , desorption , materials science , surface roughness , chemistry , surface finish , voltammetry , inorganic chemistry , nanotechnology , chemical engineering , composite material , adsorption , catalysis , organic chemistry , engineering
The well-known electrochemical probe Fe(CN)63-/Fe(CN)64- is widely used for estimating the electrochemically active area of electrodes modified with carbon nanotubes, conductive polymers, enzymes, etc. In this study, we used the platinum electrode, smooth or platinized with different roughness factors, to demonstrate that such a redox couple fails to respond to a surface roughness variation. We determined the roughness factors of the Pt surfaces by atomic force microscopy (AFM) images, which yielded values between 2.72 and 25.91. Almost the same values were found by using the charge of the hydrogen monolayer desorption obtained from steady-state cyclic voltammetry experiments performed in an acid medium. They were then compared with those provided by peak current in voltammetry or chronoamperometry with Fe(CN)6 3-/Fe(CN)64- which all yielded values nearly to one. Such comparison demonstrates that the electrochemical behavior of the redox probe is an outer sphere reaction with a quite small interaction with the electrode surface, thus not being suitable to be related with active areas.