Boosted Light-Excited NO<sub>2</sub> Detection Based on Hierarchical Z-Scheme MoS<sub>2</sub>/SnO<sub>2</sub> Heterostructure Microspheres at Room Temperature
Yong Yang, Shenman Yao, Wufei Gong, Yan Liang, Ting Yu, Cailei Yuan
Abstract
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 MoS 2 /SnO 2 is designed and prepared. The heterostructure demonstrates an outstanding NO 2 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 NO 2 along with acceptable response/recovery properties. The physical mechanism of NO 2 sensing is analyzed. The results suggest that the construction of the Z-scheme heterostructure between MoS 2 and SnO 2 can greatly promote the separation of photogenerated carriers so that more photogenerated carriers can take part in the NO 2 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.