Ultrafast and low-hysteresis humidity sensors based on mesoporous LaFe_0.925Ti_0.075O₃ perovskite

Humidity sensors are omnipresent. Thus, significant efforts have been undertaken to advance their performance, for example, to have a fast detection time, negligible hysteresis, and excellent stability. Despite numerous active research endeavors, establishing a sensor that excels in all these key performances is still challenging. Here, we address this challenge by designing a capacitive-based humidity sensor employing porous LaFeO₃ perovskite. Integrating Ti into the perovskite using a sol-gel method, i.e., LaFe_0.925Ti_0.075O₃, results in a 400% increase in specific surface area achieved through pore formation, translating to a 2094% response parameter. Furthermore, due to the rapid equilibrium between adsorption and desorption processes, the sensor achieves ultrafast 4.4 s response time and 1.4 s recovery time, with <1% hysteresis and excellent stability over 28 days, when assessed at 300 K. Our work significantly advances current humidity sensor performance and, in a broader context, emphasizes the efficacy of porous (perovskite) materials for high performance gas detection.