Creation of Nanoporous Ag Surface Layers through a Two-Stage Electrochemical Deposition-Dissolution of Zn and Intercalation-Deintercalation of Chloride Ions in an Ionic Liquid Bath

Abstract

A one-pot two-stage process involving electrochemical deposition-dissolution of Zn (Zn-ECDD) and electrochemical intercalation-deintercalation of chloride ions (Cl-ECIdI) in an ionic liquid bath of 1-ethyl-3-methylimidazolium chloride and ZnCl2, was developed to nanostructure surface layers of metallic silver. Cyclic voltammetric measurements show that (i) the cathodic deposition of Zn onto Ag substrate occurs at around E < −1.0 V and its corresponding anodic dissolution commences at E > −0.85 V; and (ii) the intercalation and deintercalation of chloride driven by the oxidation and reduction of Ag electrode itself commence at very close potentials (−0.03 V) in the corresponding cathodic and anodic scans. Scanning-electron-microscope studies clearly reveal that nanoporous surface layers were formed upon applying potential cycles, and the nanoporous structures can be tuned by modulating the potential range and cycle numbers. The potential cycle between −2.0 and 1.5 V enabling both Zn-ECDD and Cl-ECIdI is more efficient than the cycle between −2.0 and 0 V only enabling the Zn-ECDD. A resulting nanoporous Ag microdisc was studied as a probe for electrochemical detection of nitrite. Well-developed steady-state voltammograms and linear calibration curve were obtained. These facts suggest that the one-pot two-stage green-chemistry process based on Zn-ECDD and Cl-ECIdI is a promising surface-treatment technique for different applications.