Bilayer cascade of WO3 nanofibers/Ag@CeO2 nanosheets for ppb-level xylene detection under the catalysis-gas sensitivity synergistic mechanism

The semiconductor gas sensors used for xylene gas detection in real time has been restricted by the inadequate sensitivity and selectivity. Constructing a bilayer cascade sensor with the catalysis-gas sensitivity synergistic is considered as an effective solution. Herein, the Ag@CeO 2 nanosheets are synthesized by heat treating the Ag@Ce-MOF, which synthesized via solvothermal method. The morphological evolution of cerium metal–organic framework (Ce-MOF), regulated by Ag ions, is investigated, and the transformation mechanism is proposed. The bilayer sensors were constructed by using WO 3 nanofibers, prepared via the electrospinning method, as the sensitive layer and the Ag@CeO 2 nanosheets as the catalytic layer, respectively. The bilayer sensors exhibit remarkable performance in response to xylene. The response value ( R a / R g ) of WO 3 /Ag@CeO 2 sensor to 10 ppm xylene gas reaches 32.13 at the operating temperature of 160 °C. Additionally, the sensor displays an exceptional response to even trace amounts of xylene, as low as parts per billion (ppb). The catalysis-gas sensitivity synergistic mechanism was elucidated by capturing catalytic intermediates using online mass spectrometry. These findings provide a novel strategy for benzene series (BTEX) sensor and offer a novel approach to prepare two-dimensional Ce-MOF and its derived materials with tailored properties. Graphical abstract