Continuous monitoring of volatile organic compounds (VOCs) is an important challenge for human beings. Allinorganic halide perovskites (AIHPs) have attracted extensive attention because of their excellent semiconductor properties. Perovskite interfacial modulation engineering is considered as a key factor in the preparation of stable and high-performance AIHP devices. In this work, organic hydrophilic ligand 3-mercaptopropionic acid (MPA) is creatively introduced to regulate the nanostructure of CsPbBr 3 and construct the ambient stable binary heterojunction of CsPbBr 3 nanoparticles (NPs)/ZnO NPs. The microscopic morphology design shows that CsPbBr 3 NPs with the optimal nano size have abundant sensitive gas adsorption sites and large specific surface area, which can effectively improve the sensitivity of the CsPbBr 3 -based sensor to ethanolamine (EA). Moreover, hydrophilic groups in MPA are good for the formation of hydrogen bonds and MPA network structures, which effectively improve the binding affinity of metal oxides on MPA surfaces, enhancing the stable anchoring of ZnO to halide perovskite CsPbBr 3 and the heterojunction construction of CsPbBr 3 /ZnO. The CsPbBr 3 -2MPA/ZnO sensor displays the advantages of the lowest theoretical detection limit (DL, 31 ppb), excellent selectivity, a much shorter response time (50 s) than CsPbBr 3 , and significantly enhanced EA response (13.25, 100 ppm) at room temperature, besides the stable repeatability in more than 1 month. In addition, we propose a feasible sensing mechanism. The gas sensor based on CsPbBr 3 /ZnO nano-heterojunctions with efficient hydrophilic MPA modulation may provide constructive idea for the detection of VOCs.

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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 (R a /R g ) 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.

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