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

TiO 2 nanoparticles (NPs) and Au-TiO 2 core-shell NPs (C-S NPs) were synthesized for xylene gas detection. Morphological, phase, and chemical studies demonstrated the successful generation of Au-TiO 2 C-S NPs with a cauliflower-like morphology and desired composition. Also, the surface area of TiO 2 NPs was 8.46, which increased to 23.88 m2/g for Au-TiO 2 C-S NPs, due to the creation of a porous TiO 2 shell around the Au core. The response of the TiO 2 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 TiO 2 NPs gas sensor has no selectivity to xylene gas, the TiO 2 C-S NP gas sensor exhibited excellent selectivity. Overall, incorporation of Au in TiO 2 in the form of a C-S structure improved the performance of the sensor to sense xylene. Improved xylene sensing for the TiO 2 C-S NPs stemmed from the high surface area and porous nature, oxygen defects, and formation of Au-TiO 2 Schottky barriers. This research demonstrates the development of high-output xylene sensors by means of Au-TiO 2 with a C-S structure. • Synthesis of cauliflower-like Au-TiO 2 core-shell (C-S) NPs for Xylene sensing studies. • Au-TiO 2 C-S NPs showed higher surface area (23.88 m2/g) relative to TiO 2 NPs (8.46 m2/g). • TiO 2 NPs showed a low response of 14.19–50 ppm Xylene at 500°C. • Au-TiO 2 C-S NPs showed a response of 165.77–50 ppm Xylene at 450°C. • Enhanced sensing response was related to porous nature, high surface area and formation of Au-TiO 2 Schottky barriers. [ABSTRACT FROM AUTHOR]