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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.

International audienceA new boron doped diamond microcells (BDD) was modified, for rapid, selective and highly sensitive determination of nitrite, using a coating film of polyoxometalates (POMs), formed by cyclic voltammetry on the molecular p-phenylenediamine (PPD) functionalized BDD. The scanning electron microscopy (SEM) technique was used to examine the morphology of (PPD/SiW11) modified (BDD) electrode. It was found that (SiW11) layer was uniformly formed on the electrode surface. It was observed that (BDD/PPD/SiW11) showed excellent electrocatalytic activities towards nitrite ion. Under the selected conditions, the anodic peak maximum at -0.6V was linear versus nitrite concentration in the 40 mu M-4 mM range, and the detection limit obtained was 20 mu M. The newly developed electrode has been successfully applied to the determination of nitrite content in real river water samples

(1a) with potentially accessible micropores as demonstrated by single-crystal X-ray diffraction measurements. Electron paramagnetic resonance spectroscopy analysis of 1 has also been assessed.

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