Ultra-fast and highly selective room-temperature formaldehyde gas sensing of Pt-decorated MoO3 nanobelts

Abstract Formaldehyde is one of the most serious threats to human health owing to the wide-spread of indoor decoration of modern buildings in recent years. The online monitoring of formaldehyde concentration of the indoor environment has become an urgent issue in modern society. In this work, an ultrafast and highly selective room-temperature formaldehyde gas sensor based on the semiconductor nanomaterials was developed. The Pt-decorated MoO3 nanobelts were employed as the formaldehyde sensing materials, which were synthesized through hydrothermal and chemical reduction process. The results show that the Pt nanoparticles loading on the surface of the nanobelts are metallic and well crystalized. After the surface-decoration by Pt nanoparticles, the room-temperature HCHO sensing performance of the MoO3 nanobelts could be greatly enhanced. With only 0.61% (atomic ratio) of Pt nanoparticles loading on MoO3, the sensor response towards 200 ppm of HCHO could be increased from 5.7% to 39.3%. The average response and recovery rate were also improved, leading to ultrafast response and recovery process at room temperature. At the LOD (limit of detection) of 1 ppm, the response and recover time of the sensor was only 8.8 s and 0.94 s, respectively. Furthermore, the Pt-decorated MoO3 nanobelts also exhibited outstanding selectivity against other typical interference VOC including methylbenzene, methanol, ethanol and acetone, as well as good anti-interference performance towards water vapors. The great improvement of the sensor performance could be attributed to the spill-over and catalytic effect of Pt nanoparticles toward HCHO at room temperature.