A high-performance NH3 gas sensor based on TiO2 quantum dot clusters with ppb level detection limit at room temperature

Nanometer sized aggregates of titanium dioxide quantum dot clusters (QDs) were used with a convenient low temperature (80 degrees C) hydrolysis method to prepare a high performance NH3 gas sensor. Using transmission electron microscopy, the synthesized material was found to consist of massive anatase TiO2 QDs (66 nm) with excellent stability and dispersibility (the individual QDs were formed from 2 to 5 nm diameter anatase crystals). The unique preparation method yielded a highly porous TiO2 QDs structure with a huge specific surface area (315.74 m(2)/g). This provides more potential reaction sites on the surface potential enhancing the performance of the sensor. Testing revealed these NH3 (g) sensors demonstrated excellent gas sensing properties (0.2-10 ppm, room temperature), high sensitivity, selectivity, stability, low detection limit (0.2 ppm), rapid response recovery (88 s/23 s for 0.2 ppm), and a linear response to concentration.