Correlating surface growth of nanoporous gold with electrodeposition parameters to optimize amperometric sensing of nitrite

Nanoporous gold (NPG) films were electrodeposited on a gold substrate and the generated platform was used for amperometric determination of nitrite. The electrochemical characterization of different NPG surfaces showed that the electrocatalytic activity concerning the nitrite anodic oxidation is strongly modulated by changes in the electrodeposition parameters. Microstructural analysis using scanning electron microscopy, profilometry and X-ray diffraction revealed changes in the deposited layers, following a unique growth mechanism strongly dependent on applied potential and electrodeposition time. Accordingly, more negative potentials resulted in changes in morphology from highly branched standing flakes to flat dense surfaces, whereas higher electrodeposition times led to the evolution of nanodendrites. NPG electrodes prepared by electrodeposition at 4 V for 100 s were selected as the best platform for nitrite determinations at 0.77 V. Evaluation of sensing characteristics demonstrated the sensor exhibits a very fast response time (<4 s), a detection limit of 10 nM and two linear ranges (1-110 mu M and 110-2000 mu M) with sensitivity values found to be 0.02 mu A mu M-1 cm(2) and 0.012 mu A M-1 cm(-2), respectively. Other analytical properties such as reproducibility, selectivity and long term stability were also investigated and the results showed the fabricated sensor has favorable features for detection of nitrite in real samples, as demonstrated in experiments involving successful nitrite determinations in meat and lake water samples. (C) 2018 Elsevier B.V. All rights reserved.