Anatase TiO2 aerogel with high specific surface areas and porous network structures for ultra-fast response hydrogen sensor

To better ensure the safe preparation, storage, transportation, and use of hydrogen, it is critical to find a convenient and effective method to monitor requests. In this study, an excellent hydrogen gas sensor based on the TiO2 aerogel structure with a high specific surface area has been successfully fabricated. In addition, we have obtained TiO2 aerogel with anatase crystal form and rutile crystal form through high-temperature crystallization to further explore the influence of TiO2 nanoparticles and TiO2 aerogel crystal form on the performance of hydrogen sensors. The results show that the sensitivity of anatase TiO2 aerogel hydrogen sensor to 100 ppm H2 at 450 °C is 3.1271, higher than TiO2 nanoparticles (1.4942), amorphous TiO2 aerogel (2.1796) and rutile TiO2 aerogel hydrogen sensor (2.8464), and it exhibits ultra-rapid response recovery characteristics, with a response time of 4 s and a recovery time of 29 s, respectively. Besides, the sensitivity of anatase TiO2 aerogel hydrogen sensor to 100 ppm H2 is twice that of 100 ppm ammonia (1.5668), 2.5 times that of 100 ppm methanol (1.2731), and 1.1 times that of 100 ppm ethanol, showing that anatase TiO2 aerogel has good selectivity in a complex gas environment. The 30 days repeatability test shows that the anatase TiO2 aerogel hydrogen sensor has good stability and linearity (100–1000 ppm H2 concentration). Finally, this work proposes a hydrogen sensing model, which is used to describe the hydrogen sensing mechanism of TiO2 aerogel, indicating that the high specific surface area and high porosity of TiO2 aerogel play an important role in hydrogen detection. Hydrogen sensors based on TiO2 aerogel are rarely reported at present, and this work has an important reference and guidance role for the future in-depth industrial research of hydrogen sensors.