Role of Nitric Acid Concentration in Silver Nitrate Electrolysis: Implications for Silver Recovery in Waste Photovoltaic Modules

Effective photovoltaic module recycling is essential for improving the sustainability of solar technologies and securing the silver supply chain. One method of recycling silver from end‐of‐life photovoltaic modules is electrodeposition following nitric acid leaching. This study investigates how nitric acid concentration affects the electrochemistry and recovery of silver in a controlled three‐electrode system. Silver recovery and Faradaic efficiency were found to increase with acid concentration from 0.1 м. Maximum values of 97% silver recovery and 96% Faradaic efficiency at 4.0 м nitric acid were observed using a silver working electrode at constant current deposition of −20 mA/cm 2 . Past this point, both recovery and efficiency were observed to decline sharply due to enhanced silver dissolution kinetics. It was also found at low nitric acid concentrations (<2.0 м) silver oxynitrate formed as a solid deposit at the counter electrode, while at higher concentrations (>2.0 м) silver (II) complexes formed but remained dissolved in the electrolyte. Industrially, a nitric acid concentration in the range of 2.0–4.0 м is recommended to optimize silver recovery and efficiency while minimizing anode fouling in a full cell arrangement.