Electrografting and electropolymerization of nanoarrays of PANI filaments through silica mesochannels

Vertically aligned mesopomus silica films electrogenerated on indium-tin oxide (ITO) electrodes are used as hard templates for the electrochemical growth of polyaniline (PANI) nanofilaments. To ensure proper adhesion of PANI to the underlying ITO surface, aniline moieties are first covalently attached to the bottom of mesochannels via electrografting of aminophenyl diazonium cations, serving in a second step as precursors for PANI growth by electropolymerization of aniline through the silica mesochannels. This was achieved by cyclic voltammetry or potentiostatically at an applied potential of +0.85 V (vs. Ag/AgCl), the latter offering a better control of the nanofilaments length by tuning the electropolymerization time. PANI wires remain attached to ITO after etching of the silica membrane, confirming the importance of initial electrografting. Although PANI nanofilaments in the silica membrane remain electroactive, enhanced peak currents were observed after silica removal as PANI nanofilaments offer a larger effective surface area to the electrolyte solution.

Automated summary

In this study, vertically aligned mesoporous silica films were used as hard templates for the electrochemical growth of polyaniline nanofilaments on indium-tin oxide electrodes. Aniline moieties were first attached to the bottom of mesochannels and served as precursors for PANI growth. After removal of the silica membrane, enhanced electroactivity of PANI nanofilaments was observed due to the larger effective surface area they offer.