Targeted surface modification of Cu/Zn/Ag coatings and Ag/Cu particles based on sacrificial element selection by electrodeposition and redox replacement

Abstract

The electrodeposition-redox replacement (EDRR) method was investigated for the preparation of two types of functional surfaces. A synthetic solution simulating Zn process solution containing 65 g/L Zn, 200 ppm Cu, 2 ppm Ag and 10 g/L H2SO4 was used as the source for creating functional surfaces EDRR experiments. The effects of operating parameters such as deposition potential (E1), deposition time (t1), and redox replacement time (t2) have been comprehensively studied. When E1 was selected to deposit Zn as the sacrificial metal, coherent Cu/Zn/Ag coatings with various chemical compositions, crystalline phases and surface morphology were obtained depending on the selected t1 and t2. The Cu/Zn/Ag coatings also exhibited competitive corrosion resistance (Ecorr = −683 to −634 mV vs. Hg/Hg2SO4, jcorr = 1.6–4.1 μA/cm2) when compared to those detailed in the literature. In contrast, when E1 was selected so that Cu was the sacrificial metal, separated Cu/Ag particles with controllable chemical composition, particle size (82–170 nm) and tunable surface plasmon resonance (SPR) behavior were formed through the variation of t1 and t2. In addition to the ability to tailor different functionalities for the surfaces from the same solutions, the process was performed in a single electrochemical cell without the addition of any complexing agents. Overall, these promising results demonstrated the versatility of the EDRR method to create various high value-added functional materials from complex hydrometallurgical solutions which contain multiple metal impurities.