Abstract
In this work, we have developed an electrochemical sensor for nitrite detection, based on a polyoxometalate (POM) namely mono-lacunary keggin anion [SiW11O39]8﹣ cited as (SiW11). Electrochemical characterization of SiW11 shows two-step reduction processes, with formal potentials of ﹣0.5 V (I) and ﹣0.68 V (II). Oppositely charged polyelectrolyte (poly (allylamine hydrochloride) (PAH)) and (SiW11) were assembled alternately to modify glassy carbon electrode. The electrochemical behavior of the modified electrode was studied in detail using cyclic voltammetry (CV). The results showed that SiW11/PAH/GC electrode present good electrocatalytic activity for the reduction of nitrite. The sensor showed a dynamic range from 100 μM to 3.6 mMof nitrite and no interference from other classical anions. Experimental factors that affect electron-transfer rate in these films, such as pH effect and layers number, were systematically analyzed.
Highlights
The presence of nitrite in groundwater and atmosphere is an essential precursor in the formation of nitrosamines, many of which have been proven to be powerful carcinogens [1,2,3]
We show the capability of SiW11O39]8− cited as (SiW11) anion immobilized by electrodeposition and LBL methods, for the electrocatalytic reduction of nitrite and this property is applied for the first time for the design of a selective amperometric sensor for nitrite
The prepared compound was characterized by infrared spectroscopy, and cyclic voltammetry in acidic aqueous solution, because Keggin type and its derivative are unstable in neutral and basic solutions
Summary
The presence of nitrite in groundwater and atmosphere is an essential precursor in the formation of nitrosamines, many of which have been proven to be powerful carcinogens [1,2,3]. Polyoxometalates (POMs), a large family of charged, nanoscopic inorganic clusters, are attractive materials for electrode modification because of their reversible redox behavior, good chemical stability and electronic conductivity [22] These compounds are resistant to oxidative degradation due to the fact that their fundamental elements are in their higher oxidation state [23,24,25,26]. Layer-by-layer (LBL) self-assembly has proved to be a promising method for the fabrication of ultrathin films It is based on the alternate adsorption on the substrate surface of oppositely charged species from dilute solutions and film formation is attributed primarily to electrostatic interaction and Van der Waals forces. We show the capability of SiW11 anion immobilized by electrodeposition and LBL methods, for the electrocatalytic reduction of nitrite and this property is applied for the first time for the design of a selective amperometric sensor for nitrite
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