Ambient Stable CsPbBr₃/ZnO Nanostructures for Ethanolamine Sensing

Continuous monitoring of volatile organic compounds (VOCs) is an important challenge for human beings. All-inorganic 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 CsPbBr3 and construct the ambient stable binary heterojunction of CsPbBr3 nanoparticles (NPs)/ZnO NPs. The microscopic morphology design shows that CsPbBr3 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 CsPbBr3-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 CsPbBr3 and the heterojunction construction of CsPbBr3/ZnO. The CsPbBr3-2MPA/ZnO sensor displays the advantages of the lowest theoretical detection limit (DL, 31 ppb), excellent selectivity, a much shorter response time (50 s) than CsPbBr3, 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 CsPbBr3/ZnO nano-heterojunctions with efficient hydrophilic MPA modulation may provide constructive idea for the detection of VOCs.