Synthesis and Formation of Phase-Tuned TiO2-/Ionic Liquid-Incorporated Polymeric Membranes for Ammonia Sensing at Room Temperature

Gas sensors based on polysulfone (Psf) composite membranes incorporated with ionic liquids (ILs) and phase-tuned titanium dioxide (TiO2) were successfully prepared using a solution-casting method. The influence of the addition of ILs and TiO2 on membrane properties was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, atomic force microscopy, and X-ray photoelectron spectroscopy. The gas-sensing properties of the composite membranes were investigated by evaluating the change in resistance as a function of time in the absence and presence of gas inside a chamber. The sensing studies showed that Psf/TiO2, Psf/TiO2 with 1-decyl-3-methylimidazolium chloride, and Psf/1-ethyl-3-methylimidazolium hexafluorophosphate membranes exhibited faster response and recovery times to ammonia at various concentrations ranging from 1 to 150 ppm at 25 °C. Moreover, the sensors were easy to fabricate, and are thus promising to be used in real-life applications.