UV Irradiation of Au-Modified SnO₂ Nanorods Enabling the Rapid Detection of Low-Concentration NO₂ at Room Temperature

The development of simple and low-cost materials and methods that are suitable for use in sensors with excellent NO2-sensing properties is of great importance to the commercialization of NO2 sensors. Here, Au-modified SnO2 nanorods (Au/SnO2 nanorods) were synthesized via a hydrothermal method combined with photodeposition. The UV light-activated sensor fabricated from Au/SnO2 nanorods was found to exhibit excellent sensing properties for NO2 at room temperature, including a high response of 10 (at a concentration of 1 ppm), a theoretical detection limit of 21 ppt, and a fast response/recovery time of 1/5 s ( ${T}_{{60}}$ ) and 22/38 s ( ${T}_{{90}}$ ). In addition, the sensor exhibited good selectivity, repeatability, and long-term stability. The sensor was found to have a good response to NO2 in a high-humidity environment. The excellent sensing properties of Au/SnO2 nanorods for NO2 can be attributed to the charge transfer between Au and SnO2, and the catalytic sensitization of noble metals. The presence of water molecules in the high-humidity environment was found to enhance the NO2-sensing performance of the developed material.