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Abstract
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We fabricated a novel water sensor for some organic solvents based on a modified gold electrode with naphthalene conducting polymers. To achieve this goal, different modified gold electrodes with poly(1,5-diaminonaphthalene) (PDAN), poly(1,5-diaminonaphthalene/titanium dioxide) (PDAN/TiO2), poly(1,5-dihydroxynaphthalene) (PDHN), and poly(1,5-diaminonaphthalene-co-1,5-dihydroxynaphthalene) (P(DAN-co-DHN)) were prepared by an in situ electropolymerization method and used for water sensing. The polymer samples were characterized by FT-IR spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical properties of the electrode samples were studied using cyclic voltammetry and conductivity measurements. The results indicated that deposition of TiO2 nanoparticles on the modified poly(1,5-diaminonaphthalene) gold electrode surface (Au/PDAN) induced improvement of the current, increasing the limit of linearity, sensitivity, and detection limit as high as the other modified electrodes. The response of the Au/PDAN/TiO2 water sensor in organic solvents including acetonitrile, ethanol, and methanol was evaluated under optimized conditions. The results demonstrated that the proposed Au/PDAN/TiO2 water sensor has long-term storage stability and also 95–98% of the initial sensitivity up to 30–36 days. The limit of detection for Au/PDAN/TiO2 was determined to be below 0.01% at low concentration, which was comparable to that obtained from the Karl Fisher titration method and other modified electrodes.
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