WO₃/Ru@CeO₂ Bilayer Gas Sensor for ppb-Level Xylene Detection Based on a Catalytic-Sensitive Synergistic Mechanism

Volatile aromatic hydrocarbons present a significant threat to both the environment and human health. However, due to the low reactivity of toxic gases containing benzene rings and insufficient selectivity of existing sensors, real-time monitoring of benzene series (BTEX) gases remains a challenge. The development of catalytically sensitive synergistic bilayer sensors offers a promising strategy to overcome this challenge. A series of Ru@CeO₂ nanosheets with different Ru doping levels were synthesized by using a simple solvothermal and further calcination method. Interestingly, the incorporation of Ru effectively modulates the morphology of Ce-BDC from nanorods to porous nanosheets. The WO₃/Ru@CeO₂ bilayer sensor is constructed by using WO₃ nanofibers as the lower sensitive layer and Ru@CeO₂ as the upper catalytic layer. At the operating temperature of 160 °C, the response value (R_a/R_g) of the WO₃/Ru@CeO₂ bilayer sensor to 5 ppm xylene is 37.04, which is obviously better than that of the WO₃ nanofiber sensor. In addition, the sensor also reacted significantly to low concentrations of xylene, as low as 1 ppb. Additionally, the combination of online mass spectrometry and density functional theory was employed to validate the enhanced sensing performance arising from the synergistic mechanism between the catalytic and sensing materials. Hence, the work presents a new material for detecting ppb level BTEX through an effective bilayer structure design and material selection.