AC-driven interfacial electrodeposition of silver

Two-dimensional interfacial electrodeposition of silver is studied under alternating square-wave electric potential conditions, at the water/dichloromethane interface. The overall rate of growth is found to increase with frequency. The deposit's morphology also depends strongly on the frequency: at ≤ 10 Hz compact deposits are formed while at 1-10 kHz highly ramified structures develop, the branches in which tend to broaden out at higher frequencies. At∼100 Hz a highly disordered growth is observed. A novel pulsating behavior of the deposit size is observed, with alternating contractions and growth phases. The contractions are attributed to a mechanical compaction of the newly-formed deposit, driven by the fast changes in surface tension due to the voltage variation. The mechanical oscillations induce hydrodynamic stirring in the solution, affecting the mass-transport of the reacting silver ions to the electrode, and, consequently, the rate of growth and morphology of the deposit.