Bipolar Effects in Hetero Electrodepositions in ZnSO$_4$ Solution

Electrodeposition is a popular method to grow materials. Normally, both electrodes and solutions consist of the same type of element, such as zinc electrodes in zinc sulfate. While depositing zinc ions onto copper electrodes, we have found a drop in the voltage across the cell. This drop is due to two competing reactions: Zn$^{2+}$ + Cu$\to $ Cu$^{2+}$ +Zn and Cu$^{2+}$ +2e$\to $ Cu. Upon further investigation we have found that the time drop is dependent on the voltage applied across the cell. We propose this could be used to build a solution diode.