Ti₃C₂T_<i>x</i> MXene-Derived Metal–Organic Frameworks for Room Temperature NO₂ Detection

This work reports a new method toward creating two-dimensional (2D) conductive metal-organic frameworks (MOFs) for enhanced gas sensing applications. By employing Ti₃C₂T_<i>x</i> MXene as a metal precursor and 2-aminoterapthalic acid as an organic linker, MXene-derived MOFs with high surface reactivity were synthesized. The Ti₃C₂T_<i>x</i> MXene sensor, initially selective toward NH₃ gas, was tailored to detect NO₂ gas by integrating it with MXene-derived MOFs, which offer abundant active sites on the surface. The resulting MOF sensor exhibited a notable sensing response of 76.52%, with rapid response and recovery times of 31.5 and 80.2 s, respectively, at room temperature and 35% relative humidity (RH). The sensor's specificity toward acidic NO₂ gas was attributed to the acid-base interaction facilitated by the organic linker, inducing detectable changes in resistance. Additionally, the fabricated MOF sensor demonstrated excellent repeatability and stability under ambient conditions. Remarkably, the sensor exhibited a low detection limit (LOD) of 5 ppb for NO₂ gas. These findings underscore the potential of utilizing 2D MOF sheets derived from MXene precursors for practical gas sensing applications, highlighting their versatility and effectiveness.