Visible light activated excellent NO_2 sensing based on 2D/2D ZnO/g-C_3N_4 heteroj unction composites

摘要

In this work, 2D/2D ZnO/g-C3N4 heterojunction composite was synthesized through an ultrasonic mixing and subsequent calcination process. The gas-sensing performance to NO2 was investigated at room temperature activated by visible/ultra-violet LED light sources. Noticeably, when ZnO/g-C3N4 composite is illuminated by 460 nm light, it exhibits the highest response of 44.8 to 7 ppm NO2, and the response and recovery time is 142 and 190 s, respectively. Furthermore, it possesses excellent repeatability and selectivity to NO2, and the limit of detection is 38 ppb. In addition, the effect of humidity on the sensing performance under visible light was also investigated. The excellent gas-sensing performance is attributed to the absorbance of g-C3N4 in the visible light region and the charge separation at the interface between ZnO and g-C3N4.