Boosted Light-Excited NO₂ Detection Based on Hierarchical Z-Scheme MoS₂/SnO₂ Heterostructure Microspheres at Room Temperature

Light excitation has been developed as an economical way to realize room-temperature gas sensing recently. However, the high recombination rate of photogenerated carriers in semiconductor gas sensing materials leads to very limited carriers that can effectively take part in sensing reactions, which greatly restricts the further performance improvement of gas sensing under light excitation. Here, a hierarchical Z-scheme heterostructure microsphere of MoS2/SnO2 is designed and prepared. The heterostructure demonstrates an outstanding NO2 sensing performance at room temperature with the excitation of a low-power LED light (0.06 W), which exhibits an ultrahigh sensitivity of 264.2 to 10 ppm of NO2 along with acceptable response/recovery properties. The physical mechanism of NO2 sensing is analyzed. The results suggest that the construction of the Z-scheme heterostructure between MoS2 and SnO2 can greatly promote the separation of photogenerated carriers so that more photogenerated carriers can take part in the NO2 sensing reaction. Furthermore, the designing of a hierarchically porous structure can provide abundant active sites for gas sensing reactions. The work not only expands the development of Z-scheme heterostructures in gas sensing but also provides a strategy to promote the performance of light-excited gas sensors by designing a Z-scheme heterostructure with a hierarchically porous structure.