Renewable-surface amperometric nitrite sensor based on sol–gel-derived silicomolybdate–methylsilicate–graphite composite material

Abstract

A new type of silicomolybdate–methylsilicate–graphite composite material was prepared by the sol–gel technique and used for the fabrication of an amperometric nitrite sensor. The silicomolybdic anion acts as a catalyst, the graphite powder ensures conductivity by percolation, the silicate provides a rigid porous backbone and the methyl groups endow hydrophobicity and thus limit the wetting section of the modified electrode. Cyclic voltammetry, square-wave voltammetry and chronoamperometry were employed to characterize the sensor. The amperometric nitrite sensor exhibited a series of good properties: high sensitivity (1.771 μA mmol⁻¹ dm³), a short response time (7 s), remarkable long-term stability and especially reproducibility of surface renewal in the event of electrode surface fouling.