Voltage-Dependent Copper Electrodeposition and Apparent Faradaic Efficiency in a Copper Sulfate Electroplating Cell
Arav Jain
Abstract
Electroplating is an electrochemical process in which metal ions are reduced onto a conductive surface; its practical usefulness is dependent on the amount of metal deposited and the efficiency of with which electrical charges produce the desired reactions. This study investigated how applied voltage affects copper electrodeposition and calculated Faradaic efficiency in a copper sulfate electroplating cell. Copper electrodeposition was conducted using a copper anode, nickel cathode, and 250 cm3 of 0.50 mol dm-3 aqueous copper (II) sulfate. The applied voltage varied from 1.00 V to 5.00 V, in 1.00 V increments, while electrolysis time (300 s), electrode spacing (2.0 cm), submerged electrode area, solution volume, and electrode preparation were held constant. The mean copper mass deposited had increased from the initial 0.020 g at 1.00 V to 0.050 g at 4.00; however, it then remained similar at 5.00 V within the measurement’s precision. Under the idealized model used in this study, calculated Faradaic efficiency decreased from approximately 101% at 1.00 V to 47% at 5.00 V. The apparent efficiency above 100% at the lowest voltage is attributed to the small, measured mass relative to balance resolution. These results are indicative that higher voltages can increase deposition rate but may reduce electrochemical efficiency because of side reactions, heating, polarization, and non-idealistic current behavior.
