Electrochemical High Concentration Oxygen Sensing Using a Phosphonium Cation Based Room Temperature Ionic Liquid: Analytical Studies

Detecting oxygen at the high concentration limit needs innovation. Room temperature ionic liquid trihexyl(tetradecyl)phosphonium trifluorotris(pentafluoroethyl)phosphate [P_6,6,6,14][FAP] was tested as a solvent for oxygen detection through the electrochemical reduction of oxygen. Cyclic voltammetry of oxygen in nitrogen or carbon dioxide mixtures at different partial pressures was studied. The steady state current was shown to be linearly dependent on the oxygen partial pressure in high oxygen content (>77 %) systems. Simultaneous detecting of oxygen and carbon dioxide is also realised in an oxygen/carbon dioxide mixture, providing proof‐of‐concept of high concentration oxygen and carbon dioxide dual sensing.