TiO2/NaNbO3 heterojunction for boosted humidity sensing ability

TiO2, NaNbO3, and TiO2/NaNbO3 nanomaterials were fabricated by the hydrothermal method. The humidity sensing properties of impedance sensors based on the single and composite materials were systematically studied. Our results show that the TiO2/NaNbO3-based sensor shows superior sensing performances, including ultrahigh sensitivity of 125512, rapid response/recovery time 11/15 s, extremely low hysteresis less than 2%) as well as excellent stability. These sensing parameters are much better than those of TiO2- and NaNbO3-based sensors. At the same time, we found that the sensitivity of the TiO2/NaNbO3-based sensor can be controlled by a small dc bias. Complex impedance analysis reveals that the TiO2/NaNbO3 heterojunction plays an important role in boosting the humidity sensing properties.