Preparation and Mechanism Analysis of High-Performance Humidity Sensor Based on Eu-Doped TiO₂

TiO₂ is a typical semiconductor material, and it has attracted much attention in the field of humidity sensors. Doping is an efficient way to enhance the humidity response of TiO₂. Eu-doped TiO₂ material was investigated in both theoretical simulations and experiments. In a simulation based on density functional theory, a doped Eu atom can increase the performance of humidity sensors by producing more oxygen vacancies than undoped TiO₂. In these experiments, Eu-doped TiO₂ nanorods were prepared by hydrothermal synthesis, and the results also confirm the theoretical prediction. When the doping mole ratio is 5 mol%, the response of the humidity sensor reaches 23,997.0, the wet hysteresis is 2.3% and the response/recovery time is 3/13.1 s. This study not only improves the basis for preparation of high-performance TiO₂ humidity sensors, but also fills the research gap on rare earth Eu-doped TiO₂ as a humidity-sensitive material.