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.

All-inorganic halide perovskites, as a dominant member of the perovskite family, have been proven to be excellent semiconductors due to the great successes for solar cells, light-emitting diodes, photodetectors, and nanocrystal photocatalysts. Despite the remarkable advances in those fields, there are few research studies focusing on gas and humidity-sensing performances, especially for pure CsPbBr3 and heterogeneous CsPbBr3@MoS2 composites. Here, we first report a valuable CsPbBr3 sensor prepared by electrospinning, and the excellent gas sensing performances are investigated. The CsPbBr3 sensor can quickly and effectively detect ethanolamine at room temperature. The response time is only 16 s, and the response to 100 ppm ethanolamine is as high as 29.87, besides the excellent repeatability and good stability. The theoretical detection limit is estimated to be 21 ppb. Furthermore, considering the irreplaceable role of heterostructures in regulating the electronic structure and supporting rich reaction boundaries, we also actively explored the EA sensitivity of inorganic CsPbBr3-based heterogeneous composites CsPbBr3@MoS2. At the same time, the roles of the critical capping agents OA and OAm are systematically investigated. This work demonstrates the great potential of all-inorganic halide perovskites in promising volatile organic compound detection.

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.

2D transition-metal dichalcogenides (TMDs) have attracted much attention for promising application in gas sensors. Edges of the layered nanostructures are well known as highly reactive sites, besides the low working temperature. However, TMD sensors still suffer from the bottlenecks of low response and slow reaction kinetics. We propose an innovative use of porous carbon nanostructures originated from zeolitic imidazolate frameworks. In this work, multi-layered MoS 2 nanoplates are confined in nanoscale porous carbon nanocages (PCNCs) by a facile hydrothermal technique. The carefully designed MoS 2 /PCNC sensor exhibits good triethylamine (TEA) sensing performances. Compared with pure MoS 2 , the response (R a /R g ) of the MoS 2 /PCNC composite sensor to 100 ppm TEA is as high as 53. The theoretical TEA detection limit is estimated to be as low as 12 ppb. In addition, the investigation proves good stability and reproducibility. The possible sensing mechanism for the improved performances is discussed too. The innovative strategy for the controlled design of MoS 2 /PCNC nanostructures may provide valuable application in designing high-performance TEA sensors.

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