In situ crystal plane derivation engineering of MOF/MXene inducing electron backflow effect for enhanced triethylamine sensing

Triethylamine (TEA) presents considerable threats to public health and production safety because of its toxic and explosive nature, highlighting the urgent need to develop high-performance sensing materials. Traditionally, gas-sensing elements based on p-type metal oxide semiconductor (MOS) have been hindered by their intrinsically low carrier mobility, resulting in performance inferior to n-type MOS. Herein, we successfully constructed Cr₂O₃/TiO₂-X (MCT-X) heterostructures through a in-situ MOF/MXene-derived strategy. The abundant porous nature, along with its increased specific surface area and numerous surface defects, facilitated the interaction between TEA and active centers. Meanwhile, the tightly coupled p-n heterostructures not only enabled rapid carrier migration but also exhibited a rare electron backflow effect. The multidimensional synergistic effects conferred upon MCT-X with excellent sensing properties. The optimal MCT-2 exhibited an outstanding response of 450.01 for TEA (100 ppm, 134 °C), along with superior selectivity, linearity, and stability. Density Functional Theory (DFT) calculations reveal in-depth explanation of the anisotropic charge transport mechanism induced by differences in crystal planes contacts and the sensitization mechanism of the heterostructure. This distinctive synthesis approach, combined with comprehensive mechanistic analysis, offers a strategy for the design of advanced TEA sensing materials.