The development of 2D copper branched aggregates

Abstract

2D copper branched aggregates were grown from the electrodeposition of Cu +2-ions on a small cathode in a 2D electrochemical cell with a concentrical anode — cathode arrangement at different applied voltages (ΔE). As ΔE is increased in the 9 V < ΔE < 15 V range, the number of branches in the aggregates increases leading to isotropic deposits. Under this condition, the electrodeposit mass (M) and the radius of gyration of the object (R) fit a M α R DM relationship with a mass fractal dimension, D M = 1.67±0.04, whereas R and electrodeposition time (t), fulfill a R α t proportionality. The D M value is as predicted by DLA models, in contrast to the linear R vs t dependence. The analysis of aggregate patterns and the radial velocity dependence on ΔE indicate that the growth of large branches is mainly controlled by the electric field between the cathode and the anode, whereas small branches grow under diffusion control. This fact can explain the discrepancy between the D M value which is mainly determined by the small DLA-like branches, and the radial growth rate value which is exclusively determined by the growth of the large branches.