Electrodeposition of Ni–Cu alloys from a protic ionic liquid medium-voltammetric and surface morphologic studies

• Electrodeposition of Ni–Cu alloy was done in a low cost PIL, TEATFA.
• Potential for reduction of Cu and Ni becomes close, leading to effective co-deposition.
• Porosity and the surface roughness of the Ni–Cu alloy depend on the quantity of Cu.
• Ni–Cu alloy containing more than 27% of Cu has low corrosion resistance.

Electrodeposition of Ni, Cu and Ni–Cu alloys had been carried out in triethylammonium trifluoroacetate (TEATFA) medium on a glassy carbon (GC) electrode. Voltammetric investigations reveal that the reduction potential of Cu and the onset cathodic decomposition potential of Ni become close to each other favouring effective co-deposition of both these metals in TEATFA. Porosity and the surface roughness of the Ni–Cu alloys (obtained by constant potential electrolysis) considerably depend on the quantity of Cu, as confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). X-ray diffraction (XRD) reveals that the increase of Cu content in the Ni–Cu alloy leads to a decrease in the intensity ratio of I(111)/I(200) and a shift to low 2θ value for Ni (1 1 1) plane. Potentiodynamic polarization and EIS analysis confirm that the Ni–Cu alloy containing more than 27% of Cu has low corrosion resistance.