Enhanced formaldehyde gas sensing properties of p-LaFeO3/n-Fe2O3 composite nanofibers synthesized by electrospinning method

Abstract

Formaldehyde sensors play a key role in indoor and outdoor air quality detection. In this study, LaFeO₃/Fe₂O₃ composite nanofiber sensor with heterogeneous structure was prepared by electrospinning technology. Compared with LaFeO₃ nanofibers, the diameter of LaFeO₃/Fe₂O₃ composite nanofibers is reduced from 200 nm to about 180 nm, and the surface micro-cracks become more compact. The gas-sensing test results showed that the response value of LaFeO₃/Fe₂O₃ composite nanofibers was significantly improved compared with pure LaFeO₃. In particular, the S3 (LaFeO₃:Fe₂O₃=10:1) sensor has a response value of 38.46, and its optimal operating temperature is reduced from the original 180 ℃ to 120 ℃, which further broadens its practical application range. On this basis, the sensing mechanism is discussed in detail by surface oxygen adsorption and space charge model, and the density functional theory (DFT) is used to analyze the sensing mechanism. The improvement of the response value is mainly attributed to the unique morphology, abundant oxygen vacancy, large specific surface area and the formation of p-n heterojunction. This study provides experimental basis and theoretical support for the preparation of high-performance LaFeO₃-based gas sensors.