Synergistic Effects of PdO-CuO Loadings on Methyl Mercaptan Sensing of Porous WO Microspheres Prepared by Ultrasonic Spray Pyrolysis.

In this work, PdO-CuO co-loaded porous WO microspheres were synthesized with varying loading levels by ultrasonic spray pyrolysis (USP) using polymethyl methacrylate (PMMA) microspheres as a vehicle template. The as-prepared sensing materials and their fabricated sensor properties were characterized by X-ray analysis, nitrogen adsorption, and electron microscopy. The gas-sensing properties were studied toward methyl mercaptan (CHSH), hydrogen sulfide (HS), dimethyl sulfide (CHSCH), nitric oxide (NO), nitrogen dioxide (NO), methane (CH), ethanol (CHOH), and acetone (CHO) at 0.5 ppm under atmospheric conditions with different operating temperatures ranging from 100 to 400 °C. The results showed that the CHSH response of USP-made WO microspheres was collaboratively enhanced by the creation of pores in the microsphere and co-loading of CuO and PdO at low operating temperatures (≤200 °C). More importantly, the CHSH selectivity against HS was significantly improved and high selectivity against CHSCH, NO, NO, CH, CHOH, and CHCOCH were upheld by the incorporation of PdO to CuO-loaded WO sensors. Therefore, the co-loading of PdO-CuO on porous WO structures could be promising strategies to achieve highly selective and sensitive CHSH sensors, which would be practically useful for specific applications including biomedical and periodontal diagnoses.