Ultrasensitive detection of xylene gas by cauliflower-like Au-TiO₂ core-shell nanoparticles

TiO₂ nanoparticles (NPs) and Au-TiO₂ core-shell NPs (C-S NPs) were synthesized for xylene gas detection. Morphological, phase, and chemical studies demonstrated the successful generation of Au-TiO₂ C-S NPs with a cauliflower-like morphology and desired composition. Also, the surface area of TiO₂ NPs was 8.46, which increased to 23.88 m²/g for Au-TiO₂ C-S NPs, due to the creation of a porous TiO₂ shell around the Au core. The response of the TiO₂ NPs to 50 ppm xylene was 14.19 at 500°C, while it increased to 165.77 at a lower temperature (450°C). Furthermore, while the TiO₂ NPs gas sensor has no selectivity to xylene gas, the TiO₂ C-S NP gas sensor exhibited excellent selectivity. Overall, incorporation of Au in TiO₂ in the form of a C-S structure improved the performance of the sensor to sense xylene. Improved xylene sensing for the TiO₂ C-S NPs stemmed from the high surface area and porous nature, oxygen defects, and formation of Au-TiO₂ Schottky barriers. This research demonstrates the development of high-output xylene sensors by means of Au-TiO₂ with a C-S structure.