Study of the electropolymerization of tetrakis (3-aminophenyl) porphyrin Fe(III) chloride on Au electrodes by cyclic voltammetry and STM

Conducting tetrakis (3-aminophenyl) porphyrin Fe(III) chloride films are prepared by electropolymerization on Au(1 1 1) electrodes in DMF + TBAP solutions by cycling the potential between −1.6 and 1.5 V vs. SCE at 0.2 V s−1. The film thickness is controlled through the number of cycles and the voltammetric response of the modified electrode is stable and reproducible. STM images show that during the first 20 cycles only 2D islands 0.35 nm high and up to 50 nm long are formed. These islands grow laterally by the incorporation of new oligomers on their borders. When the electrode surface is almost fully covered a transition from 2D to 3D growth is observed. This transition in the growth mode can be followed through the anodic charge of the cyclic voltammograms.