Electrochemical Synthesis of Nanocrystalline CuAg Coatings on Stainless Steel from Cyanide-Free Electrolyte

Herein we demonstrate a novel plating bath, free from cyanide, to plate a highly adherent nanocrystalline copper-silver (ncCuAg) coating on a stainless-steel substrate and its application as an antimicrobial coating. The microstructures, such as the grain size, texture, microstrain, and the crystalline preferential orientation of CuAg deposits, are systematically investigated by X-ray diffraction analysis. The range of 13.4-16.6 nm was discovered to be the crystallite size determined from the X-ray peak broadening (Scherrer's formula). Both HRTEM, FESEM-EDS, XPS, and mapping analysis revealed that the ncCuAg coatings are composed of both Ag and Cu atoms. Electrochemical processes occurring during CuAg co-deposition were investigated by using linear sweep voltammetry (LSV), cyclic voltammetry (CV), and anodic linear stripping voltammetry (ALSV). Additionally, the coatings made of ncCuAg produced by these baths work well as antibacterial agents against gram-positive (Staphylococcus) and gram-negative bacteria (Escherichia coli).