Electrochemical Growth of Ag/Zn Alloys from Zinc Process Solutions and Their Dealloying Behavior

Abstract

This study investigates the sustainable preparation of Ag/Zn alloys from a simulated zinc process solution (20 ppm Ag, 65 g/L Zn, and 10 g/L H2SO4) via electrodeposition-redox replacement (EDRR) and the electrochemical dealloying behavior of the Ag/Zn alloys. Results indicate that Ag/Zn deposits with diverse compositions and microstructures can be obtained at room temperature without any complexing agents, simply by varying EDRR parameters like deposition time, deposition potential, and redox replacement time. Two types of Ag/Zn intermetallics (Zn0.96Ag0.04 and Ag0.76Zn0.24) were identified by the combination of X-ray diffraction (XRD) and anodic linear sweep voltammetry. Mass-transfer limitations have significant effects on the growth process, and a nucleation-growth mechanism from Ag/Zn particles into dendrites with increased EDRR cycles is introduced: with EDRR parameters favoring mass-transfer limitations (higher overpotentials, longer deposition times, and shorter redox replacement times), a more dendritic morphology of Ag/Zn alloys is achieved. The selective dissolution of Zn (i.e. dealloying) allowed the formation of silver-rich surfaces with an enhanced surface plasmon resonance behavior, which can be readily tuned by EDRR and dealloying parameters. These results highlight the significant potential of the EDRR-dealloying route to produce different types of Ag/Zn alloys and optically functional materials directly from base metal process solutions.