Synthesis of 1D LaFeO3 nanofibers/2D MXene heterostructures for formaldehyde detection at low temperature

Gas sensors play an indispensable role in air quality monitoring. In this paper, the LaFeO3 nanofibers/Ti3C2TX MXene composite sensor composed of one-dimensional (1D) porous LaFeO3 nanofibers and two-dimensional (2D) Ti3C2TX MXene nanosheets was prepared by electrospinning and electrostatic self-assembly technology. The morphology, structure and phase composition were analyzed by various techniques. The results show that the diameter of LaFeO3 nanofibers is about 150 nm, and the fibers are evenly distributed on the surface of the accordion-like MXene multilayer nanosheets. Gas-sensing test data show that compared with pure LaFeO3, LaFeO3 nanofibers/Ti3C2TX MXene composite sensor has excellent response value (18.86) and better stability to formaldehyde gas. Besides, its optimal operating temperature is reduced from the original 180 degrees C to 60 degrees C, which widens 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 and structure, the increase of specific surface area and the formation of p-p heterojunction. This study provides a new idea and innovative way for LaFeO3-based gas sensors.