Visible light activated excellent NO2 sensing based on 2D/2D ZnO/g-C3N4 heterojunction composites

In this work, 2D/2D ZnO/g-C 3 N 4 heterojunction composite was synthesized through an ultrasonic mixing and subsequent calcination process. The gas-sensing performance to NO 2 was investigated at room temperature activated by visible/ultra-violet LED light sources. Noticeably, when ZnO/g-C 3 N 4 composite is illuminated by 460 nm light, it exhibits the highest response of 44.8 to 7 ppm NO 2 , and the response and recovery time is 142 and 190 s, respectively. Furthermore, it possesses excellent repeatability and selectivity to NO 2 , 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-C 3 N 4 in the visible light region and the charge separation at the interface between ZnO and g-C 3 N 4 .