Enhanced Room-Temperature NO₂ Sensing through Deep Functional Group Hybridization in Nitrogen-Doped Monolayer Ti₃C₂T

Nitrogen dioxide (NO₂) is a significant environmental and human health hazard. Current NO₂ sensors often lack sensitivity and selectivity under ambient conditions. This study investigates ammonia pyrolysis modification of monolayer Ti₃C₂T MXene to enhance NO₂ detection at room temperature. Nitrogen-doped Ti₃C₂T demonstrates a substantial improvement in sensitivity, with a response of 8.87% to 50 ppm of NO₂ compared to 0.65% for the original sensor, representing a 13.8-fold increase. The nitrogen-doped sensor also exhibits superior selectivity and linearity for NO₂ under ambient conditions. Theoretical analysis shows that nitrogen incorporation promotes enhanced interaction between Ti₃C₂T and its surface oxygen-containing functional groups through electronic hybridization, resulting in improved adsorption energy (1.80 |eV|) and electron transfer efficiency (0.67 |e|) for NO₂, thereby enhancing its gas-sensing performance. This study highlights the potential of ammonia pyrolysis-treated Ti₃C₂T MXene for advancing NO₂ sensor technologies with heightened performance at room temperature.