AN IN-SITU SCANNING PROBE MICROSCOPY STUDY OF COPPER ELECTRODEPOSITION ON CONDUCTIVE POLYPYRROLE

The initial stages of copper electrodeposition onto conductive polypyrrole have been directly examined with in situ scanning probe microscopy (SPM). The deposition of copper onto polypyrrole is compared with the deposition of copper onto gold. We have examined copper deposition from additive-free electrolytes and also electrolytes containing an organic additive (a benzothiazole derivative, BTD). Copper electrodeposition in the absence of additives is characterised by an instantaneous nucleation and 3-dimensional growth of the copper deposit on both polypyrrole and gold substrates. In the latter case the growth mode is Stranski-Krastanov, since 3-D growth centres are formed directly on-top of the underpotentially deposited copper monolayer. The morphology of the copper growth on polypyrrole is similar both in the presence or absence of BTD. In both cases the growth is Volmer-Weber. By contrast, the morphology of the copper growth on gold is dramatically affected by this additive. in this case the copper deposit exhibits a quasi-2-D growth (quasi-Frank van der Merwe growth), with layer deposition occurring by a ''birth-and-spread'' mechanism. Possible reasons for the differences in the additive's influence upon the copper growth on gold and polypyrrole are discussed.