Ag NPs loading and ultraviolet irradiation strategies for enhancing the performance of WO3/Ti3C2TX composites in detecting 2-heptanone.

As a typical volatile organic compound (VOC), 2-heptanone detection is critical in food spoilage monitoring, chemical production safety control, and environmental pollutant tracking. However, developing a 2-heptanone gas sensor with high sensitivity at room temperature remains challenging. This study prepared WO₃/Ti₃C₂T_X MXene composites (WT-50) via a solvothermal method and constructed a ternary composite Ag/WO₃/Ti₃C₂T_X-50 (AgWT-50) by loading Ag nanoparticles. The gas-sensing properties of WT-50, AgWT-50, and WT-50 excited by ultraviolet light toward 2-heptanone were investigated. AgWT-50 exhibits a high response of 4.62 to 55.04 ppm 2-heptanone at room temperature, with excellent selectivity and stability. The UV-irradiated WT-50 (WT-50Z) demonstrates more significant performance enhancement, with a response of 6.54, which is twice that of WT-50 (3.25), and notably improved selectivity. Mechanistic studies reveal that the performance improvements of AgWT-50 and WT-50Z originate from increased oxygen vacancies induced by Ag nanoparticle loading and UV-induced high-energy hot electrons and elevated photogenerated carrier concentration, respectively. Finally, the fabricated sensor was successfully applied to evaluate the freshness of salmon, establishing a food quality monitoring model based on gas-sensing responses. This study provides a new strategy for developing room-temperature high-performance gas sensors, showing significant application potential in food quality control, public health protection, and environmental safety fields.