Preparation and performance of NaTaO3/TiO2 humidity sensors with high responsivity

Abstract

In this study, a high-performance nanocomposite NaTaO3/TiO2 humidity sensor was prepared using the hot solvent method, and its humidity sensitivity was analysed. Structural analysis indicated that the NaTaO3/TiO2 composite had a greater surface area than pristine NaTaO3. Consequently, the surface of the NaTaO3/TiO2 composite adsorbed more water molecules, resulting in enhanced humidity response. During the preparation of the composite, Ti3+ and oxygen vacancy defects formed in the NaTaO3/TiO2 composites, which contributed to the adsorption and desorption of water molecules. The Ti3+ and oxygen vacancies promoted the generation of H3O+ ions and shortened the response and recovery time of the NaTaO3/TiO2 sensor. Compared with the NaTaO3 or TiO2 individually, the aforementioned properties of the composite materials endow the sensor with superior humidity sensitivity performance. The NaTaO3/TiO2 humidity sensor exhibited impedance change over 4.5 orders of magnitude, high responsiveness (4011588%), lower hysteresis (8.5%), long-term stability, and response and recovery time (13 s and 9 s, respectively) in the relative humidity range of 11 to 95%. In addition, the complex impedance spectrum was analysed to elucidate the sensing mechanism. The preparation of the NaTaO3/TiO2 composite material provides a new direction for designing a high-sensitivity humidity monitoring resistance sensor based on NaTaO3.

Keywords

• NaTaO3/TiO2 composite
• Oxygen vacancy
• Ti3+ defects
• High response