Improving Electrochemical Sensitivity of Silver Electrodes for Nitrate Detection in Neutral and Base Media through Surface Nanostructuration

A nanostructured silver microelectrode was prepared by a green chemistry method based on electrochemical deposition-dissolution of zinc (Zn-ECDD) in an ionic liquid bath for the detection of nitrate in aqueous solution. During the cathodic process, reactive Zn was electrochemically deposited onto a Ag microdisc substrate. During the subsequent anodic process, Zn was removed from the substrate through electrochemical dissolution. Scanning-electron microscopy (SEM) and energy dispersive X-ray microscopy (EDX) measurements showed that potential cycles mediated Zn-ECDD results in nanostructured surface layers exhibiting nano-size particles and inter-particle pores, and no Zn residues were detected. The electrochemical responses of the nanostructured Ag electrode to nitrate in both neutral and basic media were studied using steady-state voltammetry. Compared to a smooth Ag microelectrode, the nanostructured Ag microelectrode demonstrated largely improved electrochemical sensitivity to nitrate in both neutral and base media. Well-developed steady-state voltammograms and linear calibration curves with improved sensitivity were obtained for the first time. These indicated that the nanostructured Ag microelectrode is a promising sensor probe for electrochemical detection of nitrate contaminant in water. (C) 2013 The Electrochemical Society. All rights reserved.