Triethylamine Gas Sensors Based on BiOBr Microflowers Decorated with ZnO Nanocrystals

In this work, ZnO nanocrystals (NCs) are innovatively decorated on the hierarchically porous microflowers (MFs) of BiOBr. The preparation is accompanied by the construction of n–n nano-heterojunctions. The crystallographic information, microstructure, oxygen vacancy, and gas sensing performances of BiOBr/ZnO composites are investigated. The BiOBr/ZnO sensor presents excellent response characteristics to triethylamine (TEA). Compared with BiOBr MFs and pure ZnO NCs, the BiOBr/ZnO composite sensor exhibits a higher response (Ra/Rg) of about 20.57 to 100 ppm TEA at 200 °C. The sensor also shows good selectivity and durable long-term stability, besides the low detection limit of 112 ppb. Even more appealingly, the response time is only 4 s. The improved TEA sensing performance of BiOBr MFs modified with ZnO NCs can be mainly attributed to the unique hierarchical heterogeneous microstructure. Furthermore, the construction of n–n BiOBr/ZnO heterostructures leads to a large specific surface area and effective electron transport, which facilitate the surface reaction and diffusion of TEA molecules. The BiOBr/ZnO composite sensor based on n–n nano-heterojunctions may provide a valuable strategy for the detection of volatile organic compounds.