High-Performance Room-Temperature NO<sub>2</sub> Gas Sensor Based on Au-Loaded SnO<sub>2</sub> Nanowires under UV Light Activation
Bo Zhang,
Shuai Zhang,
Yi Xia,
Pingping Yu,
Yin Xu,
Yue Dong,
Qufu Wei,
Jing Wang
Affiliations
Bo Zhang
Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Institute of Advanced Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
Shuai Zhang
Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Institute of Advanced Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
Yi Xia
Research Center for Analysis and Measurement, Analytic & Testing Research Center of Yunnan, Kunming University of Science and Technology, Kunming 650093, China
Pingping Yu
Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Institute of Advanced Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
Yin Xu
Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Institute of Advanced Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
Yue Dong
Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Institute of Advanced Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
Qufu Wei
Key Laboratory of Eco-Textiles (Ministry of Education), Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
Jing Wang
Key Laboratory of Synthetic and Biological Colloids (Ministry of Education), School of Chemical and Material Engineering, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
Optical excitation is widely acknowledged as one of the most effective means of balancing sensor responses and response/recovery properties at room temperature (RT, 25 °C). Moreover, noble metals have been proven to be suitable as photosensitizers for optical excitation. Localized surface plasmon resonance (LSPR) determines the liberalization of quasi-free electrons in noble metals under light irradiation, and numerous injected electrons in semiconductors will greatly promote the generation of chemisorbed oxygen, thus elevating the sensor response. In this study, pure SnO2 and Au/SnO2 nanowires (NWs) were successfully synthesized through the electrospinning method and validated using XRD, EDS, HRTEM, and XPS. Although a Schottky barrier led to a much higher initial resistance of the Au/SnO2 composite compared with pure SnO2 at RT in the dark, the photoinduced resistance of the Au/SnO2 composite became lower than that of pure SnO2 under UV irradiation with the same intensity, which confirmed the effect of LSPR. Furthermore, when used as sensing materials, a detailed comparison between the sensing properties of pure SnO2 and Au/SnO2 composite toward NO2 in the dark and under UV irradiation highlighted the crucial role of the LSPR effects. In particular, the response of Au/SnO2 NWs toward 5 ppm NO2 could reach 65 at RT under UV irradiation, and the response/recovery time was only 82/42 s, which far exceeded those under Au modification-only or optical excitation-only. Finally, the gas-sensing mechanism corresponding to the change in sensor performance in each case was systematically proposed.
