Effect of Pb(II) on the morphology of platinum electrodeposited on highly oriented pyrolytic graphite

Platinum films electrodeposited from 10 mM H2PtCl6 have been probed using s canning electron microscopy (SEM) and ex situ scanning tunneling microscopy (STM) to examine morphological changes produced when Pb(II) is added to th e deposition solution. Deposition was carried out potentiostatically at -25 0 and -1000 mV (vs Ag/AgCl) from solutions containing three different Pb(II ) concentrations: 0, 0.05, and 0.4 mM. The presence of Pb(II) produced an e xtremely rough, spiky morphology on the nanometer scale and suppressed dend ritic aggregation on the micrometer scale. These observations are interpret ed in terms of Pb(II) counteracting enhanced surface diffusion of Pt atoms resulting from interaction between them and chloride ions at the solution/e lectrode interface.