Ionic liquid–polymer electrolyte for amperometric solid-state NO2 sensor

A new ionic liquid–polymer electrolyte was successfully tested in the planar amperometric solid-state sensor sensitive towards nitrogen dioxide. The electrolyte consists of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) in the ratio 57:43 mol.% and exhibits ionic conductivity 1.6 × 10−4 S cm−1 at 20 °C, high electrochemical stability (over 4 V on gold or glassy carbon) and thermal stability (over 230 °C). The analyte, gaseous nitrogen dioxide in air, was determined using the electrochemical reduction at −900 mV vs. Pt/air on gold minigrid indicating electrode with Pt/air as a reference electrode. The sensor response is linear in the NO2 concentration range 0.3–1.1 ppm and is reproducible and long-term stable.

► Polymer-ionic liquid system as electrolyte in solid state gas sensor. ► Electrochemical and thermogravimetric characterisation of polymer electrolyte. ► Miniaturised gas sensor with gold minigrid indicating electrode. ► Nitrogen dioxide detection at ppm level.