Abstract
Polypyrrole(PPy) nanowire modified electrodes were developed by template-freeelectrochemical method based on graphite electrode. The modified electrode wascharacterized by their amperometric response towards nitrate ions. Before reduction ofnitrate ions, electrochemical solid-phase extraction (EC-SPE) of nitrate in/on modifiedelectrodes was conducted. It is found that the unusual nanowired structure of polypyrrolelayer (instead of well known cauliflower structure) allows us to increase the effectivesurface area of the electrode and subsequently the sensitivity. And the effects ofelectrochemical preparation parameters of PPy nanowire modified electrodes on theircorresponding characters were evaluated. The experimental results show that theelectrochemical preparation parameters of the modified electrodes such as scan rate,polymerization potential, temperature of polymerization solution and polymerization timehave significantly effects on the morphology of PPy nanowires and subsequently effectivesurface area of the electrode and electroreduction current density of nitrate. Thedetermination sensitivity may be varied according to the modification parameters. Under acertain polymerization conditions, the corresponding sensitivity reaches 336.28 mA/M cm2 and the detection limit is 1.52×10-6 M. The proposed method was successfully applied in thedetection of nitrate in the real samples.
Highlights
Conductive polymers have received considerable attention in recent years
PPy nanowires were successfully prepared on the electrode surface by templated-free method electrochemically in our laboratory
The results indicate that the corresponding reduction current density is determined by the effective surface areas of the electrodes, and the structure of the modified PPy nanowires
Summary
Conductive polymers have received considerable attention in recent years They have unique optical, chemical, and electrical properties. Many methods for nitrate determination have been developed in recent years, for example, spectroscopic, chromatographic, and electrochemical detection, etc [4-9]. These methods are either laborious to perform or complicated or not sufficiently specific. PPy nanowires were successfully prepared on the electrode surface by templated-free method electrochemically in our laboratory. Electropolymerization parameters might affect the morphology of PPy. A detail study of these conditions enables optimization of the response of the prepared electrode to the NO3-, as well as aiding in the development of strategies toward the rational design of sensors. The selectivity, sensitivity and detection limit for the optimal PPy nanowiresbased nitrate-selective electrode were improved greatly
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