| NO2 is one of the main toxic gases that can cause environmental pollution.Trace amounts of NO2 will not only directly harm the human respiratory system,but also cause air pollution.Therefore,it is crucially important to develop the gas sensor to detect toxic and harmful gas?NO2?immediately.The two-dimensional material Sn S2 has good application in the field of gas sensing,in addition,the sensing material based on the 2D Sn S2 has stronger electronegativity and adsorption capacity.Therefore,the Sn S2-based gas sensor has the advantages of high sensitivity and selectivity,besides,also has the characteristics of fast response/recovery,which is relatively rare in two-dimensional materials.However,pristine Sn S2-based sensors need to work at 120 ?,so the currently main goal is primarily concerned about the detection of NO2 at room temperature while maintaining high sensitivity,fast response/recovery and good selectivity.Firstly,the flower-like structure of Sn S2 is more required for the improvement of the sensing performance.Secondly,studies have shown that the performance can be improved by constructing heterostructure.In particular,materials with Fermi energy levels higher than Sn S2 are used to construct heterostructure with Sn S2,which not only takes the own advantage for Sn S2,but also significantly improves sensing performance.Based on the above background,this thesis employed hydrothermal method to synthesize flower-like Sn S2/Ti O2 hierarchical heterostructure.Sn S2/Ti O2 heterostructure exhibited excellent response/recovery performance at RT compared with pristine Sn S2.The heterostructure show high sensitivity of 319% to 1 ppm NO2 at RT,besides,exhibit short response/recovery time?58/169 s?,excellent cycle stability and outstanding selectivity.Overall,the Sn S2/Ti O2 heterostructure not only work normally at room temperature,but also have better sensing performance.The sensing mechanism starts from the geometric effect.Ti O2 particles are dotted on the surface of the flower-like Sn S2,which further increases the specific surface area of the material,so that the performance is more superior.Secondly,starting from the electronic effect,the current method of constructing Sn S2/Ti O2 heterostructure not only reduces the resistance of Sn S2,but also forms chemical bonds at the interface,which are conducive to improve sensing performance.This work may open up new possibilities for further improvement of Sn S2-based nanocomposites with even higher sensing performances.This study demonstrates that Sn S2/Ti O2 heterostructure is an efficient route to develop next-generation gas sensors with improved sensing performance. |
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