Nucleation and growth mechanism of electroformation of polypyrrole on a heat-treated gold/highly oriented pyrolytic graphite

Nucleation and growth mechanism of polypyrrole (PPy) films was investigated on vapor deposited gold/highly oriented pyrolytic graphite (Au/HOPG) after heat treatment by means of current-time transient (i-t) measurements and t apping mode atomic force microscopy. It was found that the nucleation and g rowth was a progressive 3-D before and after nuclei overlapping. However, t he mechanism was 2-D instantaneous before nuclei overlapping and 3-D progre ssive after nuclei overlapping on a Au/HOPG substrate without heat treatmen t. The change in mechanism was due to lower surface defects on a heat-treat ed Au/HOPG substrate than on a bare Au/HOPG substrate. Images of PPy on a h eat-treated Au/HOPG contained zig-zag and nodular structures. (C) 2001 Else vier Science Ltd. All rights reserved.