Electrodeposition of monodisperse copper nanoparticles on highly oriented pyrolytic graphite electrode with modulation potential method

Copper nanoparticles with size of 51 nm and R.S.D.dia of 10% can be obtained by modulation potential electrodeposition: first, a −0.8 V × 120 ms potential step was used to nucleate copper particles on highly oriented pyrolytic graphite (HOPG) electrode surface, where nuclei with a supercritical size were formed, secondly, a 0.082 V × 80 ms strip peak potential (Es) was used to strip smaller metal nuclei partly, at last, a growth potential, −0.28 V was applied to grow the nearly identical size slowly. Mechanism of copper electrodeposition on HOPG electrode from a solution of 1 mM CuSO4 and 1.0 M H2SO4 has been studied using cyclic voltammogram and chronoamperometry. In copper electrodeposition the charge-transfer step is fast and the rate of growth is controlled by the rate of mass transfer of copper ions to the growing centers. Reduction of Cu(II) ions did not undergo underpotential deposition. The initial deposition kinetics of Cu electrocrystallization corresponds to a model including progressive nucleation and diffusion controlled growth.