Pd and Pd-B modified g-CN monolayer as innovative sensor and scavenger for CO, NO2, C2H2 and C2H4: A DFT study

Abstract

The prompt detection of toxic gases like CO, NO2, C2H2, and C2H4 is crucial for both environmental preservation and industrial safety. In this work, we investigate the adsorption behavior and sensing performance of these four gases on both intrinsic g-CN and g-CN modified with single Pd atom and Pd-B pair, denoted as Pd-g-CN and Pd-B-g-CN, respectively, utilizing the first-principles calculations. The results indicate that the introduction of Pd atom and Pd-B pair significantly enhances the adsorption effect of g-CN monolayer toward these gases, with adsorption energies ranging from − 0.44 eV to − 1.43 eV. Furthermore, all adsorptions are identified as chemisorption, with the adsorption strength following the order of NO2 > CO > C2H4 > C2H2. Additionally, the adsorption of NO2, C2H2, and C2H4 induces notable changes in the work function of Pd-g-CN and Pd-B-g-CN, as well as approximately a 20-time increase in the bandgap of Pd-g-CN. Moreover, the Pd-g-CN and Pd-B-g-CN monolayers exhibit reasonable recovery times for C2H2 and C2H4, measured as 0.04 s and 6.40 μs at 298 K, respectively. Furthermore, NO2 can be rapidly desorbed from the Pd-B-g-CN surface at 398 K, with a short recovery time of 8.17 s. Therefore, the Pd-g-CN and Pd-B-g-CN monolayers can be regarded as potential gas-sensitive materials for the detection of C2H2 and C2H4 at room temperature, respectively. These research findings provide robust theoretical support for the design of novel gas sensors and efficient toxic gas adsorbents.