Highly sensitive and selective gas sensors based on nanoporous CN monolayer for reusable detection of NO, H2S and NH3: A first-principles study

Abstract

To explore the possibility of the nanoporous CN (p-CN) monolayers as high-performance gas sensors, the adsorption, electronic properties and gas-sensing performance of various gases on the p-CN monolayers have been studied by first-principles methods. Only NO, SO2, H2S and NH3 have weak chemisorption on the monolayer, which and the physical adsorption of NO2 and C2H4 changed efficiently the electronic properties and work function of p-CN monolayer. The p-CN monolayer towards NO, NH3, and H2S gases has comparatively high sensitivity, while has quite low sensitivity towards other gases. The characteristics on the I-V curves and work function can effectively distinguish various gases. The recovery time for NO, NH3, and H2S is about 4.1 s, 0.27 s, and 0.018 s at 300 K, respectively, which is fairly moderate for the reuse of the CN-based sensor for NO, NH3, and H2S detection. However, the over-short (or over-long) recovery time for NO2 and C2H4 (<10−6 s) (or SO2, c. 35 min) gravely hinders the p-CN-based gas sensors for these gases monitoring. Therefore, the p-CN monolayers as reusable gas sensors have high sensitivity and selectivity at room temperature for NO, H2S and NH3 detection.