Room-Temperature Ammonia Gas Sensor Based on TiO2 Aerogel With Enhanced Surface Hydroxyl Density: Preparation and Performance

Although TiO 2 aerogel has structural advantages, they often suffer from low sensitivity in NH 3 detection. To improve the response of ammonia (NH 3 ) sensing at room temperature (25°C), this study aims to increase the concentration of surface hydroxyl groups. The sol-gel method and ambient pressure drying are used to prepare TiO 2 aerogel, and the influence of the molar ratio of water in the precursor solution is studied. The results show that when the water molar ratio was 19.7%, the TiO 2 aerogel sensor exhibits a significant response 14.12 to 50 ppm NH 3 . The enhanced sensing response is attributed to the adsorption of NH 3 onto the abundant surface hydroxyl groups via hydrogen bonding. And the aerogel framework provides active sites (e.g., –OH and oxygen vacancies) that favor NH 3 adsorption. This work provides a method to fabricate room-temperature NH 3 sensors with improved performance using TiO 2 aerogels. Compared with previously reported TiO 2 aerogel NH 3 sensors, this work achieves a shortened response time. Despite long recovery time and humidity-induced response suppression, the TiO 2 aerogel structure provides a foundation for future room-temperature NH 3 sensors. Graphical TiO 2 aerogels were synthesized via a sol-gel method followed by ambient pressure drying. The obtained material exhibits short response time and good selectivity toward ammonia (NH 3 ). The structural properties were characterized by XRD, FT-IR, FE-SEM, XPS, and BET. The TiO 2 aerogel shows a response of 14.12 toward 50 ppm NH3, with response/recovery time of 4/140 s.