Copper nanowires as higly sensitivite electrode for nitrate ions in water

Agricultural and livestock sectors are the main sources of nitrate ions contamination in water and foodstuff. [1]. High nitrate concentration is dangerous for both environment (algae overgrowth) and human health. Nitrate ions can be converted in different harmful nitrogen based compound such as NO2-, NO, N-nitroso compounds [2] that are responsible of several diseases such as cancer, Parkinson [3-4]. For these reasons, the Environmental Protection Agency, has established the maximum amount of nitrate ions in drinkable water at 44 mg/l, limit that is valid in many European countries [5]. Generally, spectroscopy techniques are the most used because allow to carry out analyses with high precision and reaching low LOD but it requires skilled workforces and specific instrumentations, besides the procedure is long and hard [6]. In this frame, electrochemical sensors can be used as easy, fast, cheap and not-lab-depended technology to detect nitrate ions with high selectivity and sensitivity. Copper is one of the more sensitive material to detect nitrate due to its low overpotential for reduction of NO3- to NO2- [7-9]. In this work, we have developed a Cu-NWs based electrode obtained by template galvanic deposition into nanoporous membrane. The overall process is cost effective, scalable, fast and Cu NWs of well anchored to a copper current collector can be easily obtained. Using this kind of nanostructured electrode, the surface area of the sensor is of about 70 time higher of bare ones and this is a special property for electrochemical devices. A low LOD of about 9.1 µM, (≈ 100 times lower than EPA limit) and a wide linear range were found. The effect of many interferents (Mg2+, CO3--, Cu2+, Pb2+, Zn2+, Ni2+, Hg2+, Ag+, Al3+, SO4--, Na+) was studied and nitrate ions were also successfully detected in real water samples (river, rain and drinking water)