A novel amperometric O-2 gas sensor based on supported room-temperature ionic liquid porous polyethylene membrane-coated electrodes

A novel solid-state amperometric O-2 gas sensor based on the supported 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) porous polyethylene membrane-coated electrodes has been proposed with its characterization. By electrochemical impedance technique, the ionic conductivity of the supported EMIBF4 membrane was estimated to be ca. 0.6 S m(-1), indicating that the supported EMIBF4 membrane (the thickness: 50 mum) can be used as a solid state ionic conductor at room temperature. The cyclic voltammograms obtained for the one-electron redox reaction of O-2/O-2(-.)(O-2(-.): superoxide ion) couple at high scan rates (> 100 mV s(-1)) showed a couple of usual redox peaks, while at low scan rates (< 30 mV s(-1)) S-shaped steady-state voltammograms similar to those obtained by rotating disk voltammetry were obtained. These results were explained on the basis of the mass transport of O-2 at the supported EMIBF4 membrane-coated electrode system. The transient and steady-state reduction currents for the reduction of O-2 to O(2)(-.)as well as the transient oxidation current for the reoxidation of O-2(-.) to O-2, which were obtained by potential-step chronoamperometry, could be used to measure the change of O-2 concentration in O-2-N-2 mixed gas stream. present O-2 gas sensor demonstrated a wide detection range, a high sensitivity and an excellent reproducibility.