Electrodeposition of Ni-Cu alloy films from nickel matte in deep eutectic solvent

Abstract Direct electrodeposition of Ni-Cu alloy films from nickel matte precursor in choline chloride (ChCl)/urea (1:2 molar ratio) based deep eutectic solvent (DES) has been investigated. The nickel matte was firstly sintered with KCl at 450 °C for 45 min to form metal chlorides (NiCl 2 and CuCl), then the chlorinated nickel matte was dissolved into ChCl/urea DES, which served as electrolyte for the electrodeposition of Ni-Cu alloy films. For comparison, electrodeposition of Ni-Cu alloy films from pure chlorides (NiCl 2 ·6H 2 O and CuCl) precursors in ChCl/urea DES has also been investigated. Cyclic voltammetry analysis confirms that the two electrodeposition processes in DES are similar, and Ni-Cu alloy films with different compositions can be deposited in a controlled manner. The phase compositions, microstructures and corrosion resistance performances of the two Ni-Cu alloy films electrodeposited from different precursors have also been investigated and compared. It is suggested that the chlorination-electrodeposition process in DES is a promising strategy for the electrochemical extraction of alloys from complex raw materials.