Bimetallic PtAu-Decorated SnO₂ Nanospheres Exhibiting Enhanced Gas Sensitivity for Ppb-Level Acetone Detection

Acetone is a biomarker found in the expired air of patients suffering from diabetes. Therefore, early and accurate detection of its concentration in the breath of such patients is extremely important. We prepared Tin(IV) oxide (SnO₂) nanospheres via hydrothermal treatment and then decorated them with bimetallic PtAu nanoparticles (NPs) employing the approach of in situ reduction. The topology, elemental composition, as well as crystal structure of the prepared materials were studied via field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The findings revealed that bimetallic PtAu-decorated SnO₂ nanospheres (PtAu/SnO₂) were effectively synthesized as well as PtAu NPs evenly deposited onto the surface of the SnO₂ nanospheres. Pure SnO₂ nanospheres and PtAu/SnO₂ sensors were prepared, and their acetone gas sensitivity was explored. The findings demonstrated that in comparison to pristine SnO₂ nanosphere sensors, the sensors based on PtAu/SnO₂ displayed superior sensitivity to acetone of 0.166-100 ppm at 300 °C, providing a low theoretical limit of detection equal to 158 ppm. Moreover, the PtAu/SnO₂ sensors showed excellent gas response (R_a/R_g = 492.3 to 100 ppm), along with fast response and recovery (14 s/13 s to 10 ppm), good linearity of correlation, excellent repeatability, long-term stability, and satisfactory selectivity at 300 °C. This improved gas sensitivity was because of the electron sensitization of the Pt NPs, the chemical sensitization of the Au NPs, as well as the synergistic effects of bimetallic PtAu. The PtAu/SnO₂ sensors have considerable potential for the early diagnosis and screening of diabetes.