High acid content as well as high cupric/cuprous ratio alsocauses an adverse effect on electrodeposition/current efficiency.Fig. 5 shows an SEM micrograph of an electrodeposited sampleprepared from such a condition. It can be seen that surface of electrodeposit is porous and grains are not adjacent. Most of the grainsare ellipsoidal and vertically oriented. Grains are ∼ 1-3 m long,grain distribution is such that porosity can be observed throughoutthe film. Such an observation supports low current efficiency. It hasbeen already reported that electrolysis of cupric chloride causes corrosion of copper cathode and causes precipitation of CuCl [23].
Although the reduction in current efficiency associated with ferricand cupric ions is expected, it is useful to note that reasonable cur-rent efficiencies are achievable without the use of a diaphragm cellor anode bags. In an industrial application, electrolyte flow con-trol or separation of anolyte and catholyte would result in greaterefficiencies.