NiO@Ni core shell for electrochemical detection of Hg ions

Heavy metals are considered as one of the most dangerous chemicals for human health. Among heavy metals, mercury is one of the most dangerous one: few ppb of Hg can cause serious damages to brain, heart, lungs and kidney. The Environmental Protection Agency setted the maximum concentration of Hg in water as 2 ppb [1] . Nowadays is very important to develop new and novel sensors for heavy metals that could be cheap, easy to use and for in-situ and real-time analysis and in this context electrochemical sensors are perfect candidates [2] . The more powerful electrochemical tequinique is Square Wave Anodic Strippic Voltammetry (SWASV), a two step techinique were the heavy metals are first deposited into the electrode surface and then are stripped out, obtaining a signal that increase with the concentration [3] . In the present work, we studied the performances of a NiO electrode obtained by mild thermal oxidation of commercial nickel foil. The electrodes has been characterized by scanning electrons spectroscopy and by X-ray diffraction. We have carried out a systematic study to optimize all the parameters of the SWASV such as pH, deposition potential and deposition time. We found that the linear range of the sensor can be controlled changing the deposition time, achieving a LOD of 0.5ppb with 12 mins of deposition.