A-site non-stoichiometric defects engineering in xPt–La0.9Fe0.75Sn0.25O3−δ hollow nanofiber for high-performance formaldehyde sensor

Artificially inducing abundant oxygen vacancies in perovskite-structured materials is an effective method to improve sensing activity. In this work, we prepared a highly sensitive and stable La0.9Fe0.75Sn0.25O3−δ hollow nanofiber by introducing A-site cation defects in LaFeO3 by electrostatic spinning technique, then combined with a water bath method to uniformly load the surface of La0.9Fe0.75Sn0.25O3−δ with well dispersed xPt (x = 0, 0.5%, 1%, and 1.5%, 2%) elements. Compared with La0.9Fe0.75Sn0.25O3−δ without Pt modification, the xPt–La0.9Fe0.75Sn0.25O3−δ sensing materials exhibited an excellent response to formaldehyde and greatly improved the overall performance of the sensing electrode, especially 1.5%Pt–La0.9Fe0.75Sn0.25O3−δ, achieving a response of 137 for 10 ppm formaldehyde at 160 °C, which is a significant improvement compared to the intrinsic LaFeO3. The improved gas-sensitive achievement is based on the abundant oxygen vacancies induced by the A-site cation defect, the large specific surface area, and the high catalytic activity of Pt(O) elements. This strategy of inducing abundant oxygen vacancies by artificially creating A-site cation defects and modifying noble metals can be used to develop more advanced and novel sensing electrodes.