Development of a high property acetone sensor based on TiO2 core-shell spheres and their sensing mechanism analysis

Acetone is a common volatile organic compound that can cause harm to human health when inhaled in small amounts. Therefore, the development of fast response and low detection limit acetone sensors becomes crucial. In this study, a core-shell spherical TiO₂ sensor with a rich pore structure was designed. This sensor exhibited excellent sensing properties, including higher responsiveness (100 ppm acetone, R_a/R_g = 80), lower detection limit (10 ppb) and short response time (8 s). The problem is that the sensing mechanism between TiO₂ and acetone is not thoroughly analyzed. To gain further insight, the interaction process of TiO₂ core-shell spheres and acetone under varying oxygen content environments was investigated by dynamic testing, X-ray photoelectron spectroscopy, in-situ Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry. The research results show that acetone not only adsorbs on the surface of the material and reacts with adsorbed oxygen, but also undergoes catalytic oxidation reaction with TiO₂ core-shell spheres. Significantly, in high oxygen content environments, acetone undergoes oxidation to form intermediates such as acids and anhydrides that are difficult to desorpt on the surface of the material, thus prolonging the recovery time of the sensor. The discovery of this sensing process will provide some guidance for the design of acetone sensing materials in the future. Meanwhile, this also imparts valuable references and insights for the investigation of the mechanism and application of other sensitive metal oxide materials.