Nanoscale electropolishing of high-purity silver with a deep eutectic solvent

Samples of high-purity (>99.9% composition) silver metal were used in electropolishing treatments with an acid-free ionic liquid deep eutectic solvent prepared from quaternary ammonium salts as an eco-friendly electrochemical polishing solution. Linear sweep voltammetry tests were utilized to determine the optimum conditions for electrochemical polishing, which exposed that relatively stable electropolishing for pure silver metals can achieved at 3.75 V with a current density of 0.064 A/cm(2). Atomic force microscopy was used for surface morphology comparisons while summarizing electrochemical polishing efficiency by providing root mean square roughness averages before and after electrochemical polishing to reveal an average decrease of 150.433 nm in RMS surface roughness, resulting in a surface eight times smoother than the original unpolished silver specimens. Digital microscopy provided an overall observation of the material interface between the treated and unpolished regions, and indicated that the high and electrical conductivity in silver specimens at conditions above steady state current densities could result in vigorous pitting on the silver anode surface, and result in a less smooth surface. (C) 2016 Elsevier B.V. All rights reserved.