The optimization of bimetallic electrodes’ sensitivity using copper nucleation on metallic substrates to detect nitrates in seawater

Abstract

• The investigation of the electrocrystallization of copper on gold, platinum and stainless steel 316L electrodes in aqueous media by cyclic voltammetry and chronoamperometry showed progressive nucleation. • The optimum theoretical cutoff charge to form sensitive bimetallic electrodes were verified experimentally by square wave voltammetry. • The modified electrodes were tested for their ability to detect low level of nitrates in seawater. The aim of this work is to highlight the beneficial impact of the nucleation mode study on controlling the electrodeposition of a metal on a substrate, in order to form high sensitivity bimetallic electrodes. Actually, optimizing the electrodeposition operating conditions allows generating the largest active surface, and so, increasing electrode sensitivity. For this purpose, the nucleation phenomena and the initial growth of copper nuclei on gold, platinum and stainless steel 316L electrodes were investigated using cyclic voltammetry (CV) and chronoamperometry in aqueous media. The experimental results were compared to theoretical models for the two possible nucleation modes: instantaneous and progressive. Chronoamperometric results showed that the electrodeposition process involves progressive nucleation for copper on the three substrates, which was confirmed by scanning electron microscopy (SEM). Optimal operating conditions were determined for the preparation of the highest active surface area. Subsequently, copper deposition runs were carried out on the three electrode substrates. The formed bimetallic electrodes were tested for their ability to detect low nitrate concentration in artificial seawater using square wave voltammetry (SWV).