Yttrium Doping of Perovskite Oxide La₂Ti₂O₇ Nanosheets for Enhanced Proton Conduction and Gas Sensing Under HighHumidity Levels

• Published in: Sensors
• Main Authors: Jian Wang, Caicai Sun, Jusheng Bao, Zhiwei Yang, Jian Zhang, Xiao Huang
• Format: Article
• Language: English
• Published: MDPI AG 2025-02-01
• Subjects: perovskite oxide; proton transport; yttrium doping; gas sensing; high humidity level
• Online Access: https://www.mdpi.com/1424-8220/25/3/901

Water molecules from the environment or human breath are one of the main factors affecting the accuracy, efficiency, and long-term stability of electronic gas sensors. In this contribution, yttrium (Y)-doped La₂Ti₂O₇ (LTO) nanosheets were synthesized by a hydrothermal reaction, demonstrating improved proton conductivity compared to their non-doped counterparts. The response of Y-doped LTO with the optimal doping concentration to 100 ppm NO₂ at 43% relative humidity (RH) was −21%, which is four times higher than that of bare La₂Ti₂O₇. As the humidity level increased to 75%, the response of Y-doped LTO further increased to −64%. Unlike the gas doping effect observed in previous studies of semiconducting metal oxides, the sensing mechanism of Y-doped LTO nanosheets is based on the enhanced dissociation of H₂O in the presence of target NO₂ molecules, leading to the generation of more protons for ion conduction. This also resulted in a greater resistance drop and thus a larger sensing response at elevated humidity levels. Our work demonstrates that proton-conductive oxide materials are promising gas-sensing materials under humid conditions.