Effect of current density on morphology of silver thin film recovered from crystalline silicon solar cell by electrochemical process

Highlights: • Various current densities were applied in electrochemical recovery of silver. • Silver deposits were obtained from experiments with high cathodic efficiency. • Silver deposits changed from granular to dendritic with increased current density. • The critical overpotential was calculated to find the optimum processing condition. - Abstract: This study presents the electrorefining of Ag from a crystalline silicon solar cell in a silver nitrate (AgNO₃) electrolyte solution at 25 °C and an evaluation of the morphology and cathodic efficiency. The equilibrium potential was determined by cyclic voltammetry in order to calculate the cathodic overpotential. Pure Ag deposits with a single phase, as defined by X-ray diffractometry, could be obtained from all experiments with cathodic efficiencies in the range 89.5–95%. The morphology of the Ag particles recovered on the cathode changed from granules to dendrites with increasing applied current density. Granular particles were observed under applied current densities of 1 and 3 mA cm⁻². Meanwhile, dendritic particles were formed at higher applied current densities of 5, 7, and 10 mA cm⁻². Cathodic efficiency tended to decrease because of hydrogen coevolution and dendritic growth during electrorefining at higher applied current densities. The critical overpotential was calculated in order to find the optimal cathode overpotential to obtain high-purity Ag deposits with high cathodic efficiency.