THE INFLUENCE OF INTERMEDIATE PARTICLES ON THE NUCLEATION OF COPPER ON POLYCRYSTALLINE PLATINUM

The influences of the Cu adatoms and Cu+ ions on the initial stages of copper electrodeposition on polycrystalline Pt in acidified copper su lphate solution have been studied by cyclic voltammetry, potentiostati c current transients, rotating ring-disk electrode (rrde), and in situ scanning tunnelling microscopy (STM). It has been established that du ring the long-time polarization of the platinum electrode, at potentia ls close to the copper equilibrium potential, the concentration of Cu ions in the vicinity of the electrode increases and a Cu microdeposit if formed. The dissolution of the microdeposit occurs very slowly and takes several minutes of potential cycling in the range of 0.27-1.25 V. While the microdeposit is present on the platinum, the electrode su rface is more active with respect to upd and bulk copper deposition. T he combination of electrochemical and in situ STM results indicates th at formation of surface alloy occurs during electrodeposition of coppe r on polycrystalline platinum. (C) 1997 Elsevier Science Ltd.