Arrays of copper nanowire electrodes: Preparation, characterization and application as nitrate sensor

Ensembles of copper nanowire electrodes (CuWNEEs) are prepared via electrodeposition in track-etched polycarbonate membranes. Three different preparation methods are compared showing that the better results in terms of sensor durability and reproducibility are achieved by pre-sputtering a thin gold film on the templating membrane and attaching it to a supporting electrode by exploiting the adhesion property and ionic conductivity of a thin Nafion interlayer. SEM-EDS analyses together with double layer charging currents measurements indicate that these arrays are formed by copper nanowires with 400 nm diameter, 10 mu m length distributed with a spatial density of 1 x 10(8) nanowires/cm(2). The voltammetric reduction of nitrate at CuWNEEs is characterized by a well-resolved cathodic peak at approximately -0.680 V vs Ag/AgCl, whose current scales linearly with the nitrate concentration in the 10-400 mu M range. The limit of detection (LOD) achieved by simple linear sweep voltammetry is in the 1.7-3.0 mu M range, depending on the CuWNEE preparation method, such LOD values being among the lowest reported up to now in the literature. The possibility to use CuWNEEs in chloride and nitrite containing water samples is demonstrated. (C) 2014 Elsevier B.V. All rights reserved.