Electrodeposition of pyrocatechol based films: Influence of potential scan rate, pyrocatechol concentration and pH

Abstract

Films based on catechols constitute a novel class of surface functionalization methods. Those films are produced by a complexation mechanism with metal cations. The deposition of films is accompagnied with the formation of colloids in solution. As an alternative, herein an electrochemical method is proposed and validated to produce films impermeable to hexacyanoferrate anions from pyrocatechol solutions at pH 5 and pH 7.4 in the absence of metallic cations. In such conditions the film deposition is slower from dopamine solutions in the same experimental conditions, most probably owing to the presence of a protonated ethylamine at pH=5. Based on the pH influence of cyclic voltammetry curves, a possible mechanism for the formation of the pyrocatechol based film is proposed. This electrochemical deposition method even if it can be applied only on conductive substrates is surface specific with no apparent change in the pyrocatechol solution. Electrochemical impedance spectroscopy shows the formation of conformal and insulating films.