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.