Fabrication of lotus-like Au@TiO2 nanocomposites with enhanced gas-sensing properties

The structure of lotus-like Au@TiO2 was directly fabricated via a simple and cost-effective hydrothermal method by carefully adjusting the molar ratio of Au to TiF4 in the precursor. (*) The crstal structure and morphology of the obtained louts-like Au@TiO2 were examined by X-ray diffraction (XRD), transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM), Brunauer-Emmett-Teller (BET) and X-ray photoelectron spectroscopy (XPS). The results indicated that perfect lotus-like Au@TiO2 hierarchical structure with Au pistil and TiO2 petal can be formed when the molar ratio of Au to TiF4 was 0.1875. Furthermore, the gas sensing test of the Au@TiO2 nanocomposites towards CO gas was also examined. The responses of the Au@TiO2-based sensors were higher than the pure TiO2-based sensor. Especially, the lotus-like 18.75 mol%Au@TiO2-based sensor presented a most outstanding gas sensing performance, including low optimal operating temperature, high sensitivity and selectivity as well as fast response and recovery time. Such sensing performance enhancement are ascribed to their unique lotus-like structures and the catalytic effect of the encapsulated Au nanoparticles (NPs).