This work presents a simple synthetic route to produce WO 3 nanofibers functionalized by catalytic Pt and IrO 2 nanoparticles and their superior acetone and H 2S sensing characteristics, demonstrating the potential use of Pt and IrO 2 nanoparticles in applications as sensors of biomarkers of diabetes and halitosis, respectively, in exhaled breath. The individual WO 3 fiber, calcined at 500 °C, was composed of small nanoparticles with a size distribution in the range of 30-100 nm. Networks of WO 3 fibers exhibited a high surface-to-volume ratio and unique morphologies, thus facilitating efficient gas transport into the entire fiber layers. Pt (4-7 nm) and Ir (4- 8 nm) nanoparticles were synthesized by polyol methods and were used as additives to decorate the surface of the WO 3 fibers. After a heat treatment, those catalyst particles were partially or fully oxidized to Pt/PtO x and IrO 2, respectively. To investigate the advantages of Pt-decorated WO 3 fibers (Pt-WO 3) and IrO 2-decorated WO 3 (IrO 2-WO 3) fibers as acetone (CH 3COCH 3) and H 2S sensing materials, respectively, we carried out gas-sensing measurements in a highly humid atmosphere (RH 75 %) similar to that of an oral cavity. The Pt-WO 3 fibers showed a high acetone response (R air/R gas=8.7 at 5 ppm) at 350 °C and a superior H 2S response (R air/R gas=166.8 at 5 ppm) at 350 °C. Interestingly, IrO 2-WO 3 fibers showed no response to acetone, while the gas response to H 2S exhibited temperature-insensitivity, which has never been reported in any other work. Thus, the highly selective cross-response between H 2S and acetone was successfully achieved via the combination of IrO 2 particles on WO 3 fibers. This work demonstrates that accurate diagnosis of diabetes and halitosis by sensing exhaled breath can be realized through the use of electrospun WO 3 fibers decorated with Pt and IrO 2 catalysts.
- Exhaled breath sensors