Au-decorated WO₃ cross-linked nanodomes for ultrahigh sensitive and selective sensing of NO₂ and C₂H₅OH

Au-decorated WO₃ cross-linked nanodomes are fabricated using soft templates composed of highly ordered polystyrene beads and self-agglomeration of Au. The distribution and size of Au nanoparticles on the surface of WO₃ cross-linked nanodomes are controlled by varying the thickness of the initial Au film. The responses of Au-decorated WO₃ cross-linked nanodomes to various gases such as NO₂, CH ₃COCH₃, C₂H₅OH, NH₃, CO, H₂, and C₆H₆ are at least 5 times higher than those of bare WO₃ cross-linked nanodomes. The response enhancement by Au decoration is dependent on the target gas, which is attributed to an interplay between electronic and chemical sensitizations. In particular, the Au-decorated WO₃ cross-linked nanodomes exhibit extremely high sensitivities and selectivities, and ppt-level detection limits to NO ₂ and C₂H₅OH at 250°C and 450°C, respectively. These results suggest that Au-decorated WO₃ cross-linked nanodomes are very promising for use in breath analysers to diagnose both asthma and lung cancer from exhaled human breath.