3D Porous MXene Nanosheet/SnO₂ Nanoparticle Composites for H₂S Gas Sensing

Due to the large band gap, most metal oxide semiconductor (MOS)-based gas sensors operate at high temperatures, which greatly limits their performance for gas sensing. In this work, we reported the successful synthesis of nanocomposites consisting of porous MXene nanosheets formed by the sublimation of sulfur and SnO 2 nanoparticles (S-PM/SnO 2 ). To prevent the restacking of MXene flakes under van der Waals force, a sacrificial S-template method was employed to transform MXene into a three-dimensional (3D) structure. The presence of MXene lowers the operating temperature. With a high response (∼30.6 – 10 ppm of H 2 S), rapid response speed (∼16.6 s – 50 ppm of H 2 S), high sensitivity (∼3.12 ppm –1 ), low detection limits (distinct response to 100 ppb H 2 S), and good selectivity at 100 °C, the sensor based on the optimal sample of S-PM/SnO 2 -6 demonstrates excellent H 2 S sensing performance. The improvement in H 2 S gas-sensing capacity can be attributed to the development of heterojunctions at the interface of porous MXene nanosheets (S-PM) and SnO 2 nanoparticles (NPs). This leads to an enlarged surface depletion region and an elevated potential barrier, which significantly amplifies the range of resistance variation. These results suggest that S-PM/SnO 2 nanocomposite has promising prospects in the realm of low-temperature and highly sensitive H 2 S detection.